Cox v Fellows

Post-operative investigations 11The respondent attended a general practitioner in late January 2009 in relation to several matters, including discomfort in the region of her liver. The general practitioner arranged for blood tests. Liver function tests showed obstructive jaundice. She was referred to Dr Kalantar, a gastroenterologist, but an ultrasound examination showed no dilation of the common bile duct. 12Subsequent radiological investigations undertaken by Dr Ketheswaran in February 2009 revealed a significant stenosis or stricture in the respondent's lower common hepatic duct, said to be due to compression by the surgical clips. However, the reference to compression by the surgical clips was shown by later examinations to be incorrect. 13On 3 March 2009, the respondent presented again to Professor Cox who reviewed the CT cholangiogram and the blood tests taken in February 2009. On the same day Professor Cox wrote to the respondent's general practitioner, Dr Whitehead. In his letter Professor Cox observed that the CT scan showed "a stricture adjacent to where the clips are in the cystic duct" and that "this coincides with the indentation by the right hepatic artery seen on the original cholangiogram", which had been taken during the course of the operation on 16 October 2008. Professor Cox also reported that he had explained to the respondent at this consultation: "... firstly that the mechanism may have been either conduction of diathermic current back along the right hepatic artery with ischemia or less likely diathermic to the clips. I am very careful and trained my registrars no[t] to diathermy anywhere near the clips so I would hope that this was not the case. Nevertheless she does have a stricture." According to the appellant's glossary of medical terms provided on the appeal, "diathermy" means the production of heat in body tissues for therapeutic purposes by high frequency currents; and "ischemia" means inadequate blood supply to a local area due to blockage of blood vessels leading to that area. A brief explanation of the diathermy instrument used in this procedure is given at [27] below. 14On 11 March 2009, Professor Cox carried out an Endoscopic Retrograde Cholangio-Pancreatography (ERCP) on the respondent. This confirmed the presence of a common hepatic duct stricture (which was tight and tapered) just above the clips on the cystic duct and about 1 centimetre below the confluence of the left and right hepatic ducts. Professor Cox was unable to pass a guide wire through the stricture. 15Dr Ng, a radiologist, carried out a Magnetic Resonance Cholangio-Pancreatography (MRCP) on 16 March 2009 and reported to Dr Ahmed giving the following interpretation of his findings: "MR CP confirms the clinical finding of marked stricturing at the level of the recent clipping of the cystic duct with marked stenosis seen at the distal CBD just distal to the common hepatic duct with proximal dilation of the main hepatic duct and all the intra-hepatic ducts. Normal calibre seen distal to the focus of stricturing of the CBD hence implicating a focal stenosis possibly at the site of the cholecystectomy clip as clinically indicated." 16Dr Ahmed, a hepatobiliary and general surgeon, examined the respondent on 19 March 2009 and carried out an ERCP on 24 March 2009. His operation report stated that it was quite apparent that there was a stricture at the level of the clips and he also observed there was a second stricture in the distal common bile duct. 17Dr Edwards, a gastroenterologist, carried out a spyglass procedure on 9 April 2009 and reported to Dr Ahmed on 14 April 2009 that the ERCP "showed a very tight stricture right at the portion of the clips applied during the laparoscopic cholecystectomy", and that he "visualised an incredibly small pinhole stricture in the bile duct. This was right next to and abutting the clips". Dr Edwards' diagnosis was a benign post-operative biliary stricture adjacent to and abutting the laparoscopically placed clip. He considered the differential diagnosis rested between a common bile duct injury and an early cholangiocarcinoma. The latter was subsequently ruled out as the respondent maintained excellent health thereafter. 18Following the spyglass procedure carried out by Dr Edwards, Dr Ahmed discounted a tumour and confirmed that such a procedure indicated that the respondent had a very tight stricture right at the point where the clips were applied during her laparoscopic cholecystectomy.

19After a number of unsuccessful attempts to treat the strictures, the respondent was referred to a surgeon at Royal Prince Alfred Hospital (RPA) where she underwent a procedure on 25 May 2009 and both of the strictures were successfully treated by Dr Waugh, head of the Department of Radiology at RPA. 20Dr Whitehead, the respondent's general practitioner, expressed the opinion in a report dated 25 October 2009 that there was little doubt the respondent had suffered a direct complication in her operation, in that she sustained a stricture of her bile duct, probably arising either from direct mechanical obstruction from placement of clips, or fibrosis from thermal injury due to clips transmitting diathermy current, and hence heat to the adjacent bile duct. 21Dr Edwards carried out further testing by way of MRI/MRCP on 12 August 2011 in response to an opinion of Dr Hugh (retained by the appellant), that the respondent's stricture was pre-existing before the operation and the most likely diagnosis was the condition known as primary sclerosing cholangitis (PSC). Dr Edwards concluded that there were no clinical findings to suggest that the respondent had PSC.

The procedure 22The usual disposition of biliary ducts is that the right and left hepatic ducts converge to form the common hepatic duct which, in turn, is joined at a lower point by the cystic duct which flows from the gallbladder. Below that point the duct is the common bile duct. Variations on this arrangement are sometimes encountered. In this case, no variations or abnormalities in the respondent's anatomy were noted by the appellant at the time of the procedure (see the operation report referred to at [9] above). 23A high level explanation of the steps involved in a laparoscopic cholecystectomy, based on the appellant's written submissions, is as follows: (1)The patient's abdominal wall is lifted clear of the liver, gallbladder and small intestine, stomach and other organs by carbon dioxide gas that is blown through a tube into the abdominal cavity. (2)A laparoscope is then inserted by the surgeon who inspects the gallbladder and other organs. Further small incisions are made in the patient's abdomen for insertion of other surgical instruments. (3)A catheter may also be inserted through one of the incisions. This allows an x-ray using the injection of dye into the ductal system (a cholangiogram) to be taken during the course of the procedure. (4)The surgeon uses clips to close off the bile duct and the artery at the base of the gallbladder. These clips remain in the patient's body. (5)The surgeon detaches the gallbladder using an electrocautery. This instrument, which was referred to at the trial as the diathermy, conducts an electric current operated by the surgeon. (6)When the gallbladder has been detached, it is pulled through one of the incisions, with the stones inside it. All of the instruments, save for the clips, are then removed from the patient's abdomen, the carbon dioxide gas is allowed to escape and the incisions are closed with sutures. 24The appellant's explanation is derived from a patient information brochure tendered at trial by the appellant, and is by no means detailed nor entirely clear. 25A video recording of a laparoscopic cholecystectomy, which the appellant made for teaching purposes in about 2005, was also tendered at the trial by the appellant. The video recording was supplemented by the appellant's evidence in chief, explaining aspects of the procedure as shown on the video. The following additional observations concerning the procedure should be noted. 26First, a laparoscope is a thin telescope-like tube which is inserted through an incision in the patient's navel. A small video camera and light attached to the laparoscope allows the surgeon to view the patient's anatomy, including the gallbladder on a video monitor. There are two such monitors, one on the patient's right side and the other on the patient's left side. When the surgeon is standing on the patient's right, the surgeon looks at the left monitor and vice versa when standing on a patient's left side. The view of the patient's anatomy on the monitor is fairly magnified. 27Secondly, the diathermy instrument is approximately 5 millimetre in diameter, and shaped at its end point with a silver hook, like an "L". The hook is the active part of the instrument when the surgeon presses a button which enables an electric current to flow through it. The remainder of the instrument is black and is insulated. By conducting the current through the diathermy instrument, the tissue which the surgeon wishes to divide is burnt by the heat produced by the current. That is, scorching occurs to the body tissues to which the diathermy is applied. In addition, the hook on the diathermy instrument may be used in a brushing movement on various parts of the patient's anatomy without the surgeon applying any current through the instrument. 28Thirdly, the appellant's high level explanation of the steps involved in the procedure referred to at [23] above omits two matters. Between steps (4) and (5) a cholangiogram is taken before the cystic duct is then dissected from the gallbladder. The purpose of the cholangiogram is to check the patient's anatomy, in particular to determine if the cystic duct is long or short and whether or not anything is kinked or tethered, which may be important for the application of the surgical clips to seal off the cystic duct before it is dissected. The surgeon dissects the cystic duct using a scissor-type instrument. The cystic duct, when dissected, retracts from the base of the gallbladder and the surgeon then detaches the gallbladder from the liver using the diathermy instrument. 29The treatment information pamphlet provided by Professor Cox to the respondent prior to the procedure identified the specific risks of laparoscopic cholecystectomy as including injury to organs near the gallbladder and injury to the bile ducts. In regards to the latter category of injuries, the pamphlet stated: "Injury to the common bile duct was thought to be more common in laparoscopic cholecystectomies than in open surgery. However, the occurrence of injury is considered rare, and patients are justified in choosing (with the counsel of a surgeon) a laparoscopic cholecystectomy."

The medical evidence 30The medical evidence before the trial judge was relevant to both causation and breach of duty. The evidence comprised that given by the appellant in chief and in cross-examination, the various reports of the medical practitioners who examined the respondent post-operatively and the evidence of the experts called by the parties, Dr Drew for the respondent and Dr Hugh for the appellant.

31The appellant gave evidence that during the early 1990s, he was trained in a number of procedures including laparoscopic cholecystectomy and was involved in developing a particular technique for this keyhole procedure at the Flinders Medical School in South Australia. The technique involved taking the gallbladder down off the liver rather than dissecting what is referred to as Calot's triangle. Calot's triangle is a medical term used to describe a "near triangular space formed between the cystic duct, the common hepatic duct and the inferior surface of segment V of the liver" (Gray's Anatomy, 40th ed (2008) at 1179). 32In explaining the usual "technique" or method of surgery and the circumstances in which the diathermy is applied, the appellant stated that the technique involved dissecting the gallbladder off the liver to the cystic duct, but not to dissect around or near the bile ducts. 33The appellant qualified this explanation by noting that occasionally where the patient's pathology was different it may be necessary to dissect around the bile ducts, but that in such event he would have recorded that circumstance in the operation report and the necessary dissection would not involve the application of diathermy, rather it would involve "blunt dissection", that is the use of a cold steel instrument and not the use of any electric current. 34Although the appellant could not recall the particular operation, he stated that he had not departed from his usual skill and care during the course of the operation on the respondent and in the manner of the use of the diathermy instrument. He stated that the cause of the stricture could not have been that he applied the diathermy current too close to the surgical clips. The appellant reasoned this was because he had done a lot of similar operations, he was very disciplined in attending to detail and sticking to the technique he used in the operation and not varying from the technique, and "there's a few things you just don't do". The appellant went on to explain that: "You just don't use diathermy close to clips, you don't use the diathermy close to the bile duct, you use a different technique and it's simply a matter of sticking to that discipline. That's what I do a lot of, that's what I trained a lot of registrars to do, that's what I talk at international and national meetings about. Its just part of what I do and it is part of the normal practise [sic] and normal care that I give to patients." 35The appellant repeated this evidence a number of times, stating that he was very disciplined with how he used the diathermy current and he followed the same rules each time. He stated emphatically that: "You just don't do what you shouldn't do." 36The appellant gave evidence that by October 2008 he had performed the same operation as he carried out on the respondent, 3,800 to 4,000 times and had since carried it out approximately a further 800 times. On each of those occasions the operation had been carried out without similar injury to that which occurred in the present case. 37The appellant said that there was an adverse risk attached to the surgery, notwithstanding the application of the highest standard of skill, attention and performance. He identified the risk of bile duct injury as occurring through abnormal anatomy or biliary anatomy, and variations of biliary and vascular anatomy, or with the gallbladder stone itself. He said that it was accepted internationally that the risk of bile duct injury was 0.3 per cent. Significantly, however, he did not refer to the risk of diathermy coming into contact with a clip as being one of the risks associated with the surgery, nor did he state that this was a recognised risk of injury.

38Dr Drew, a general surgeon, retained by the respondent, gave a number of reports. Following his preliminary file review, he reported on 17 May 2010 that it was obvious the operation was not carried out with the care which was required and the respondent did not get the result to which she was entitled. 39In his detailed report of 30 June 2010, Dr Drew expressed the opinion that the stricture was also almost certainly due to fibrosis of the common bile duct. It was common ground that this reference to the "common bile duct" is to be understood as a reference to the common hepatic duct which joins the cystic duct to become the common bile duct. He said that fibrosis of the duct was likely to be due to diathermy to the arterial supply to the duct. This could have occurred as a result of even a momentary contact between the diathermy electrode and the surgical clips, or due to diathermy to tissues very close to the duct. 40In a supplementary report also dated 30 June 2010, Dr Drew responded to specific questions put by the respondent's solicitors as follows: "(1) Bile duct injury of this type is a recognised risk of this form of laparoscopic surgery. (2) When this form of injury occurs, it later becomes obvious (in retrospect) that the requisite degree of care and skill had not been exercised during the operation. (3) ... the injury has presumably been caused by a very subtle injury to the duct by the diathermy. Care has to be taken during operation to keep the diathermy well away from the ducts." 41The reference by Dr Drew to a bile duct injury "of this type" was clarified during cross-examination as being a reference to a diathermy burn. 42In a subsequent report dated 7 July 2011 (responding to a report of Dr Hugh dated 12 April 2011), Dr Drew noted that the operative cholangiogram taken during the surgery on 16 October 2008 showed a "filling void" in the lower common hepatic duct at the level of the cystic duct clips. In Dr Drew's opinion, this defect could have been due to pressure from the hepatic artery however, it may have been due to a burn injury inflicted by the diathermy during dissection of the biliary ducts. 43Dr Drew also stated that during dissection of the anatomy around the bile ducts, electric current from the diathermy may have directly or indirectly caused a burn of the common hepatic duct. In the process of healing, scarring of the duct would have caused the stricture at that level. Dr Drew observed that the respondent appeared to be in good health and seemed very unlikely to be suffering from PSC. He concluded that it seemed probable that the respondent had a hepatic duct stricture resulting from the duct being damaged directly or indirectly by the diathermy.

44 Dr Hugh, a general surgeon retained by the appellant, gave two reports. In his first report dated 12 April 2011, Dr Hugh expressed the opinion that a stricture of the major bile ducts is a recognised complication of any form of cholecystectomy, whether laparoscopic or open, and is generally caused by injury to, or transsection of, a bile duct. 45However, in the case of the respondent, Dr Hugh's opinion was that: (a) the strictures in the bile ducts were unrelated to any event at the laparoscopic cholecystectomy; (b) that there is no plausible mechanism whereby a fibrous narrowing (stricture) could have been caused immediately by dissection or the application of the diathermy, and the conclusion is "inescapable" that the stricture existed prior to the cholecystectomy; (c) the second stricture subsequently found in the respondent's right hepatic duct was also pre-existing at the time of the cholecystectomy; (d) these were both idiopathic benign strictures of the biliary tree which were uncommon, however, the most frequent cause of multiple strictures was the condition known as PSC, a progressive disease of unknown aetiology; and (e) multiple strictures in the respondent's bile ducts were pre-existing conditions, most probably due to PSC. 46In a subsequent report dated 26 July 2011 (replying to Dr Drew's report of 7 July 2011), Dr Hugh agreed with a number of observations by Dr Drew concerning the films and reports relating to various imagings of the respondent's biliary tree. In particular, Dr Hugh agreed that the ultrasound examinations on 15 December 2004 and 14 August 2008 showed no common bile duct dilation. He also agreed that the operative cholangiogram of 16 October 2008 showed no common bile duct dilation. 47However, Dr Hugh disagreed with Dr Drew that a diathermy burn injury could have caused the appearance of a "filling void" in the lower common hepatic duct at the level of the cystic duct clips, as seen on the cholangiogram taken during the operation on 16 October 2008. In Dr Hugh's opinion, a burn of that circumferential extent would inevitably have immediately produced a hole in the wall of the duct with a consequent gush of bile, which would have been clearly visible during the procedure. 48In response to the three specific questions considered by Dr Drew in his report of 30 June 2010 (see [40] above), Dr Hugh expressed the following opinions: (1)He agreed with Dr Drew that a bile duct injury "of this type" (meaning a fibrous stricture) is a recognised risk of this form of laparoscopic surgery. A stricture may be a long-term consequence of various forms of operative injury to the bile duct including cutting (complete or partial transsection) by scissors, or by various diathermy instruments, crushing by instruments or clips, or ligation or suturing of the duct. In the great majority of cases, the injury arises because of duct misidentification by the surgeon; however Dr Hugh stated that this did not occur in this case, as the respondent's ductal anatomy was appropriately displayed by an intraoperative cholangiogram. (2)Bile duct injuries occur even in the best of hands and with the greatest of care as an outcome of a very complex and taxing operation. Dr Hugh referred to an article by Dr Way and others in 2002 which expressed the opinion that "the usual misperception error underlying laparoscopic bile duct injuries does not meet the defining criteria of medical negligence". The reference by those authors to "misperception" was a reference to mistakes involving misidentifying the common bile duct (or right hepatic duct) for the cystic duct, followed by deliberate cutting of the misidentified duct, or mistakes of performing the dissection of the cystic duct unintentionally too close to the bordering common hepatic or right hepatic duct. (3)He did not accept that a very subtle injury to the duct by the diathermy could have caused the respondent's biliary strictures. Dr Hugh maintained the view expressed in his first report that the respondent had two pre-existing biliary strictures of unexplained aetiology, but which may represent the onset of the condition known as PSC.

49The oral evidence of the medical experts was given concurrently and they were also subject to cross-examination.

50On the issue of whether the respondent's stricture was a pre-existing condition, the experts maintained the positions stated in their written reports. Dr Hugh was not prepared to accept the conclusions of Dr Edwards (see [21] above) that the respondent did not have the condition known as PSC. Dr Hugh acknowledged that PSC was an extremely rare disease; that he did not know of any other equally plausible explanation for multiple non-cancerous strictures in the respondent's biliary tree; and that he merely put forward PSC as a possible diagnosis. He later agreed that he had no plausible explanation for the respondent's stricture apart from PSC or an idiopathic benign stricture of the biliary tree, which he said meant that they happen without any perceptible cause. He was adamant that the operation had "absolutely" nothing at all to do with the respondent's stricture. 51Dr Drew disagreed that the respondent's stricture was a pre-existing condition, and said that the condition known as PSC is usually a fairly progressive condition which affects not just the bile ducts, but other parts of the body, in particular the bowel. Having regard to the fact that the respondent had been free of symptoms for a couple of years, he considered this would militate against a diagnosis of PSC.

52On the issue of what was variously referred to as the "flow void" or "filling void" shown on the operative cholangiogram (taken before dissection of the cystic duct), Dr Hugh gave evidence that: (1)this "flow void" was the location of the respondent's pre-existing stricture, which was not very significant at the time the operation was performed; (2)he considered that the operative cholangiogram showed a filling defect in the continuity of the duct system, which Professor Cox had misinterpreted at the time of the operation as being due to the right hepatic artery crossing over the common bile duct. For this reason he disagreed with the explanation given by Professor Cox in his letter of 3 March 2009, that on reviewing the cholangiogram at the time of the operation it was normal, and "there was a flow void in the common bile duct which is due to the right hepatic artery which is a common finding"; (3)there was a circumferential stricture noted in the respondent's common hepatic duct at the operation which was pre-existing, and that all strictures that produce functional narrowing are concentric; and (4)he did not believe that a momentary diathermy accident could cause a circumferential or concentric stricture or fibrosis. 53 Dr Drew disagreed with Dr Hugh's interpretation of the operative cholangiogram, and said that the white area shown on the cholangiogram was an abnormality, which could be explained in one of three ways. First, a pre-existing condition; secondly, it may be due to the hepatic artery crossing the duct and kinking it; and thirdly, it might be "blistering" of the duct if it had already been touched by the diathermy. Dr Drew discounted the first two possible explanations, and said that the abnormality was most likely blistering of the duct due to a burn to the duct at the time shortly before the picture was taken as shown in the cholangiogram. 54When later asked to explain his use of the term "blister", Dr Drew acknowledged that he had made it up. He said that he was referring to the possibility that the appearance on the duct of the defect (as shown on the cholangiogram) was possibly due to very early changes following a burn, which he likened to blistering. He said he used this term just to indicate a very early change due to heat damage. In answer to a question by the trial judge, Dr Drew said that a burning of the duct would lead to fibrosis, and that any damage to the duct is likely to lead eventually to fibrosis.

55On the issue of whether the occurrence of a bile duct injury in the form of a stricture indicates that the requisite degree of care and skill had not been exercised during the operation, Dr Hugh said that it was widely recognised in the medical literature that the risk of bile duct injury and stricture formation may happen to the most careful surgeon, even the most senior surgeon when the operation is being conducted with all due care. Dr Hugh expressed the view that it was not justifiable to say that because this form of injury has happened it must have been a want of skill and care by the surgeon. 56In the context of this general evidence by Dr Hugh, which was qualified by his opinion that the respondent's stricture was pre-existing, Dr Drew volunteered that he would like to make an "explanation", which was that he did not use the word "negligent" in his reports. Rather his statement(s) "more or less reflects" the statement made by Professor Cox in his letter of 3 March 2009, that even though he takes great care to avoid damaging the bile duct, in this particular case, Professor Cox's letter "more or less indicates that obviously that care wasn't adequate". 57Dr Drew repeated in answers to cross-examination that he was not suggesting negligence had occurred in this case. He agreed with Dr Hugh that "it could happen to any of us". Dr Drew said that: "There is no actual specified distance to keep the diathermy away from the [bile] duct, I don't know what that distance would be. Most surgeons keep away from it as much as they can in the course of the operation and yet it still happens sometimes that damage can occur." 58Dr Drew also agreed that one cannot infer backwards that because there is a diathermy accident or injury, direct or indirect, that there has been a departure from the careful, competent performance of the operation itself and went on to say that "we do not know where the boundary is between safe and unsafe use of the diathermy". 59In answer to the suggestion that he was not saying that there was some negligent or careless departure from the level of skill and care by the surgeon when this form of injury occurs, but instead "that for some reason or other the degree of care or skill ordinarily exercised by a competent surgeon went missing somewhere along the line", Dr Drew responded "[w]ell was not adequate to avoid injury". Dr Drew agreed that this type of injury could happen to the best of surgeons paying absolute attention to what he is doing. 60In his report of 6 May 2010, Dr Drew referred to studies in the USA and Europe which showed major bile duct injuries of 0.4 per cent to 0.6 per cent of laparoscopic cholecystectomies. Dr Drew agreed that diathermy accidents are one of the inevitable risks of a small percentage of laparoscopic cholecystectomies. 61Dr Drew explained that when he referred in his report of 7 July 2011 to bile duct injury "of this type", he was referring to diathermy burns to the bile duct. Both Dr Drew and Dr Hugh agreed that bile duct injury caused by diathermy in the course of an operation such as Professor Cox carried out on the respondent is a recognised risk of laparoscopic surgery. 62Dr Drew also agreed that he was not suggesting that what occurred in this case was not an inadvertent, unintended outcome even though Professor Cox was taking the greatest of care to do what he set out to do. Significantly however, Dr Drew qualified his answer by stating: "I wasn't present at the time and I have no reason to think there was any negligence on the part of the surgeon". Dr Hugh agreed with this proposition, including the qualification. 63As to the issue of the appropriate use of diathermy, Dr Drew agreed that the instruction which Professor Cox said that he gave when training registrars "not to diathermy anywhere near the clips" was appropriate, but added that he would extend such an instruction to "near the clips or the larger ducts". Dr Drew said that the risk that Professor Cox was addressing when giving such instruction to registrars not to diathermy anywhere near the clips, was a warning against the possibility of the clips conducting electric current to the duct.

Findings of the trial judge 64There was no issue as to the existence of a duty, which was admitted by the appellant, "being a duty to use such reasonable care and skill in carrying out the surgery". As to the content of the legal duty, it was pleaded, but not admitted by the appellant, that "it was a recognised risk of this form of surgery that injury can occur to the common bile duct from the diathermy electrode if it is brought too close to the duct" and that "in order to avoid this form of injury it is necessary to carefully define the position of the bile duct so as to ensure that it is not injured during the use of the [diathermy] electrode". 65As to the risk of harm through use of the diathermy instrument during the procedure, it was admitted by the appellant that at the time of the operation he "was aware of the necessity to avoid injury to the common bile duct during the use of the [diathermy] electrode". 66In summary, the trial judge found as follows. First, that it was the application of the diathermy "at or near the clip" on the cystic duct which caused the stricture in the respondent's common hepatic duct. Secondly, that the application of the diathermy at or near the surgical clip was a breach of duty because there had been a departure by the appellant from the required standard of care.

67In making the first finding as to the cause of the respondent's stricture, the trial judge considered and rejected a number of other suggested causes. 68The trial judge first dealt with the disagreement between the experts as to whether the respondent's stricture was a pre-existing condition. His Honour noted that Dr Hugh's evidence that the stricture existed prior to the operation was at odds with all of the other treating doctors and with Dr Drew, and rejected Dr Hugh's opinion for the following reasons: "1. It is contrary to the view of the defendant, Dr Edwards, Dr Ahmed, Dr Ng, Dr Cathasorian [Dr Ketheswaran], Dr Kalantar, Dr Waugh and Dr Drew. 2. Dr Hugh who has published a number of papers on hindsight called for the images to study with a microscope which he did for a considerable time to express the opinion which is one interpreting the view he had come to prior to studying the imaging and requesting it. In my view a classic example of hindsight. 3. Dr Hugh was of the view that the plaintiff suffered primary sclerosing cholangitis, PSC, as supporting his view. Dr Hugh would not accept Dr Edward's conclusions. I accept Dr Edward's conclusion that the plaintiff does not suffer from PSC or any other condition that may have caused or contributed to a stricture pre-surgery and I reject Dr Hugh's opinion. I reject that there is any other pre-existing condition that contributed at all to the stricture." 69The trial judge excluded the possibility of some pre-existing condition, cholangiocarcinoma or bile duct cancer, having caused the stricture. He then addressed the other possible causes raised by the evidence of Dr Drew, as well as the four possible explanations for the injury given by the appellant in cross-examination as (1) a current through the hepatic artery, (2) a current through the clip, (3) PSC, or (4) some other unexplained cause. 70As noted above, the trial judge accepted Dr Edward's conclusion that the respondent did not suffer from PSC and rejected Dr Hugh's opinion in this regard. As to an unknown reason for the stricture relating to the procedure, the trial judge implicitly rejected this possibility. He noted that the appellant, in a contemporaneous letter to the respondent's general practitioner, written after he had examined the respondent on 3 March 2010, reviewed the CT cholangiogram and the report of Dr Kalantar, "... expressed no possible cause as being that there was an unknown reason for the stricture to have arisen". 71The trial judge considered the disagreement between the experts as to whether the most likely cause was a diathermy burn to the common hepatic duct at the time shortly before the cholangiogram was taken. This was suggested by Dr Drew in his report of 7 July 2010 as a possible explanation of the "filling void" shown on the operative cholangiogram taken during the procedure. Dr Hugh disagreed with Dr Drew that a diathermy burn injury could have caused the appearance of a "filling void" shown on the operative cholangiogram and gave as his reason that a burn of the circumferential extent as the "filling void" would inevitably have immediately produced a hole in the wall of the duct with a consequent gush of bile, which would have been clearly visible during the procedure. The appellant also gave evidence that a diathermy burn to the bile duct would not cause a stricture, but would rather cause a hole. The trial judge accepted the appellant's submission that the evidence was against a diathermy burn to the duct. 72Having excluded a diathermy burn to the bile duct, the trial judge next considered Dr Drew's opinion that the injury was caused due to actual contact of the diathermy with the surgical clip attached to the cystic duct. The trial judge noted that Dr Drew was not cross-examined on this issue. The trial judge noted the two possible mechanisms by which diathermy injury could cause the respondent's stricture: "On Professor Cox's evidence alone, I could not be satisfied on probabilities that the diathermy coming into contact or immediate close in proximity to the clip was the cause of the injury. However, with Dr Drew's evidence and coupled with that evidence of the defendant, when one looks at the contemporaneous letter sent to the treating general practitioner, in my view the injury must have occasioned by either the current travelling through the hepatic artery or the diathermy coming into close contact with the clip." 73The abovementioned possibilities had been raised by the appellant in his letter of 3 March 2011 to the respondent's general practitioner as a possible cause of the respondent's stricture. 74The trial judge then considered the first of those possibilities (conduction of current through the hepatic artery) and excluded that possibility for the following reasons: "There is no evidence given if the diathermy should travel along the hepatic artery, whether there would be injury to the artery itself, where it would be expected that such current would travel to in order to cause injury, or whether that injury would result in something different to the injury as depicted in this plaintiff." 75Having excluded the possibility of conduct of current through the hepatic artery, the trial judge found that the cause of the respondent's stricture was the diathermy coming into close contact with the clip attached to the cystic duct, stating: "I find the evidence of all of the doctors as to the location of the stricture in immediate proximity to the clip, the evidence of Dr Drew when added to the evidence of the defendant, such that in all probability that it was the application on the diathermy at or near the clip which caused the stricture, and Professor Cox's failure to include that risk as a normal risk of surgery, with his specific reference to students being specifically pointed out this risk and Doctor's own evidence with the potentiality of injury should the diathermy come too close to the clip, satisfies me that it is not a normal risk of surgery and it is occasioned, in this instance, by the diathermy having been in contact with, or coming close to the clip itself." 76In reaching this conclusion, the trial judge indicated that he did not accept Professor Cox's evidence that he carried out the procedure with the diathermy well away from the clip and in accordance with his usual degree of concentration and excellence. The trial judge found on the balance of probability that: "There is no other reasonable explanation, except that the diathermy came into contact, or in very close vicinity of the clip, to occasion the current to cause the injury to the plaintiff as occurred here."

Breach of duty 77The trial judge noted the appellant's submission that the respondent had not established on the balance of probability that her injury was occasioned by (a) an unreasonable act or action of the appellant or (b) an unreasonable omission by the appellant, nor had the respondent discharged her onus as required by s 5D and s 5B of the Civil Liability Act 2002. The trial judge also noted the appellant's submissions that the expert witnesses had not given evidence that the appellant had not carried out the procedure in accordance with the appropriate standard of care and that the appellant's letter to Dr Whitehead dated 3 March 2011 did not contain the alleged concession that the injury to the common hepatic duct was caused by the diathermy current. 78The trial judge referred to the appellant's evidence concerning his experience in carrying out the procedure without similar injury to that occasioned to the respondent. His Honour also referred to Professor Cox's evidence, which was not disputed, of the adverse risk attached to the surgery, there being a risk of bile duct injury through abnormal anatomy or biliary anatomy, and variations of the biliary and vascular anatomy or with the gallbladder stone itself. The trial judge observed that the appellant did not mention the risk of a diathermy coming into contact with a clip as being one of those risks associated with surgery, nor did he indicate that it came within the recognised risk of injury. 79The trial judge found that the mechanism of the diathermy injury in the present case was not a normal risk of the procedure, noting: "Professor Cox's failure to include that risk as a normal risk of surgery, with his specific reference to students being specifically pointed out this risk and Doctor's own evidence with the potentiality of injury should the diathermy come too close to the clip, satisfies me that it is not a normal risk of surgery ... ." 80The trial judge held that the appellant had breached his duty of care expressing his reasons briefly as follows: "Notwithstanding the evidence of Drs Hugh and Drew which I reject in this matter as it is a matter for the court, in my view this is a breach of duty which amounts to negligence in the conduct of this operation by Professor Cox. I accept that the Professor has carried out this operation on probably 5,000 other occasions without such injury. I accept that he applies himself with due diligence, however I also accept that on some occasions, even with that occurring, there can be a departure and this occurred in this case. As I have said, I reject the evidence of Doctors Hugh, Drew and the defendant that there was no departure from the required standard of care in this case."

Civil Liability Act provisions 81The respondent's claim is governed by the provisions of the Civil Liability Act. 82The primary judge made only brief mention in his reasons for judgment of s 5D and s 5B of the Civil Liability Act. This was in the context of the appellant's submission that the respondent had not discharged her onus of proof on causation or breach of duty. Counsel for the appellant referred in his submissions below (both written and oral) to these provisions as well as s 5E, and also referred to some authorities which considered those provisions, but did not specifically address the matters referred to in s 5B(2). 83In the present case, the operation of these provisions does not, in my view, substantially affect the principles to be applied in determining the issues of breach and causation. However, such issues should always be considered in the context of the operative statutory framework (see Mobbs v Kain [2009] NSWCA 301; (2009) 54 MVR 179 at 186 [34] per McColl JA). 84The question whether the appellant breached his duty of care to the respondent is to be determined in accordance with s 5B, in particular the matters referred to in s 5B(2). Although it is frequently said that s 5B relates to breach rather than duty, the two concepts are not entirely separate (see King v Western Sydney Local Health Network [2013] NSWCA 162 at [9] per Basten JA; Lesandu Blacktown Pty Ltd v Gonzalez [2013] NSWCA 8 at [18]-[20] per Basten JA). 85Section 5B, Civil Liability Act provides: "(1) A person is not negligent in failing to take precautions against a risk of harm unless: (a) the risk was foreseeable (that is, it is a risk of which the person knew or ought to have known), and (b) the risk was not insignificant, and (c) in the circumstances, a reasonable person in the person's position would have taken those precautions. (2) In determining whether a reasonable person would have taken precautions against a risk of harm, the court is to consider the following (amongst other relevant things): (a) the probability that the harm would occur if care were not taken, (b) the likely seriousness of the harm, (c) the burden of taking precautions to avoid the risk of harm, (d) the social utility of the activity that creates the risk of harm." 86Pursuant to s 5C, the fact that a risk of harm could have been avoided by doing something in a different way does not of itself give rise to or affect liability for the way in which the thing was done, although it is not irrelevant. 87The appellant did not submit that the method of reasoning employed by the trial judge did not in substance comply with s 5B, in accordance with the issue of breach of duty of care which was to be decided. 88Sections 5D and 5E, Civil Liability Act are relevant to the issue of causation. They relevantly provide: "5D(1) A determination that negligence caused particular harm comprises the following elements: (a) that the negligence was a necessary condition of the occurrence of the harm (factual causation), and (b) that it is appropriate for the scope of the negligent person's liability to extend to the harm so caused (scope of liability). (2) In determining in an exceptional case, in accordance with established principles, whether negligence that cannot be established as a necessary condition of the occurrence of harm should be accepted as establishing factual causation, the court is to consider (amongst other relevant things) whether or not and why responsibility for the harm should be imposed on the negligent party. ... (4) For the purpose of determining the scope of liability, the court is to consider (amongst other relevant things) whether or not and why responsibility for the harm should be imposed on the negligent party. 5E In proceedings relating to liability for negligence, the plaintiff always bears the onus of proving, on the balance of probabilities, any fact relevant to the issue of causation." 89The first of the two elements identified in s 5D(1) (factual causation) is to be determined by the "but for" test: but for the negligent act or omission, would the harm have occurred? (see Adeels Palace Pty Ltd v Moubarak [2009] HCA 48; (2009) 239 CLR 420 at 440 [45]). 90No submission was made by the appellant below or on appeal in relation to the issue of "scope of liability", as that term is used in s 5D(1)(b). 91The trial judge proceeded on the correct basis that the respondent bore the onus of proving on the balance of probabilities any fact relevant to the issue of causation, as stated in s 5E.

Issues on appeal 92The appellant raised five grounds of appeal concerning the findings of fact by the trial judge, which focus on two issues:

• the cause of the respondent's stricture (grounds 1 and 2);
• whether the appellant had breached his duty of care to the respondent (grounds 3, 4 and 5). 93As to the cause of the respondent's stricture, the appellant contended that the trial judge fell into error in two ways. 94First, in finding that the stricture was caused by any act or omission occurring during the operation performed on 16 October 2008 (ground 1). Secondly, in finding that the stricture was caused by the application by the appellant of the diathermy used during the operation at or near the surgical clips (ground 2). The appellant submitted that one or other of six independent causes raised by the evidence was at least as likely as the cause found by the trial judge, and thus causation had not been established on the balance of probabilities. 95As to the question of breach of duty, the appellant contended that, even if the trial judge was correct in concluding that the appellant had used the diathermy at or near the surgical clips, the trial judge erred in three ways. 96First, in finding that the appellant breached his duty of care to the respondent in the conduct of the operation (ground 3). Secondly, in not finding that the risk of such injury could not have been avoided by the exercise of reasonable care and skill by the appellant (ground 4). Thirdly, in rejecting the evidence of medical experts who gave evidence at the hearing that there was no reason to believe that the appellant had failed to exercise reasonable care and skill in the conduct of the operation (ground 5).

Cause of the stricture (grounds 1 and 2) 97The appellant submitted that the evidence at trial raised six possible causes of the respondent's stricture. These were referred to by the appellant on the appeal as:

• cause 1 - a pre-existing condition known as PSC causing multiple strictures;
• cause 2 - an idiopathic stricture of unknown aetiology;
• cause 3 - the diathermy electrode came into contact with the surgical clip during surgery;
• cause 4 - the application of the diathermy in some other position caused the electric current to travel through the respondent's hepatic artery during the surgery (which, on the evidence, was an inherent risk which could not be avoided);
• cause 5 - the application of the diathermy too close to the respondents bile duct; and
• cause 6 - some other unknown cause related to the procedure. 98The appellant submitted that the trial judge fell into error as to the cause of the respondent's stricture because each of causes 1, 2, 4, 5 or 6 was at least equally as likely as cause 3, as found by the trial judge. 99 It may be observed, that causes 1 and 2 were advanced by the appellant in support of the primary submission that the trial judge erred in finding that the respondent's stricture was caused by any act or omission occurring during the operation on 16 October 2008. 100Causes 4 and 6 were advanced by the appellant in support of the alternative submission that the trial judge erred in finding the stricture was caused by the application by the appellant of the diathermy during the operation at or near the surgical clips (cause 3). Cause 5 was an hypothesis advanced by Dr Drew in his reports, but was rejected by the trial judge.

Cause 1 101On the hearing of the appeal, the appellant abandoned its written submission (based on the opinion of Dr Hugh) that a possible cause of the respondent's stricture was a pre-existing condition known as PSC causing multiple strictures, including the stricture in the respondent's common hepatic duct. This submission was properly abandoned as the appellant had conceded below that the respondent did not suffer from this condition. 102This left the challenge to the trial judge's consideration of four other possible causes, to that found by the trial judge (ie, cause 3).

Cause 2 103The appellant submitted that an equally possible explanation of the respondent's stricture was that the respondent suffered an idiopathic benign stricture of the biliary tree existing prior to the surgery. This was acknowledged in oral submissions on the appeal to be rare, but the appellant submitted that some people have a tendency to strictures (that is, an abnormal narrowing of a bodily passage). In support of this possibility, the appellant relied on the evidence of Dr Hugh who placed particular significance on the presence of the second stricture in the respondent's right hepatic duct. 104The appellant complains that the trial judge misstated the evidence of Dr Edwards when referring to Dr Edwards' conclusion that the respondent "did not suffer from PSC or any other condition ...". This complaint is correct. The words "or any other condition" do not appear in the report of Dr Edwards dated 31 August 2011 and properly understood, Dr Edwards only excluded PSC as a possible condition that may have caused a stricture pre-surgery. Accordingly, it is necessary to consider the other evidence relevant to cause 2. 105There was a disagreement between the experts as to whether or not the second stricture (in the right hepatic duct) was visible on the operative cholangiogram. Dr Drew gave evidence that he could not see any sign of the second stricture on the cholangiogram. Dr Hugh maintained his opinion that the images showed the presence of that stricture. The appellant did not contend that this court should resolve this difference of opinion but submitted that it was ultimately not significant, because the existence of the second stricture was not in dispute by April 2009. This second stricture post operation was said to be significant evidence that the respondent had an underlying condition that caused her to develop strictures. 106This challenge to the trial judge's findings needs to be viewed in the context of the appellant having conceded below and abandoned on appeal the related submission concerning cause 1, based on Dr Hugh's opinion that the most likely cause of both strictures was the condition known as PSC. This is significant because Dr Hugh gave evidence that he did not know of any equally plausible explanation for the stricture in the respondent's common hepatic duct other than the condition known as PSC. 107In my view, no error has been shown in the trial judge's rejection of this possible explanation of the stricture in the respondent's common hepatic duct. The most likely explanation for a pre-existing stricture advanced by Dr Hugh is no longer pressed on appeal, and Dr Hugh was unable to provide any equally plausible explanation for the stricture other than the condition known as PSC. 108Having regard to the appellant's abandonment of cause 1, and my conclusion that no error has been shown in relation to the trial judge's rejection of cause 2, it follows that ground 1 of the notice of appeal is not made out.

Cause 4 109Cause 4 involved the possible application of the diathermy in some other position during the surgery, causing the current to travel down through the right hepatic artery to the point in the respondent's common hepatic duct where the stricture occurred adjacent to the clips on the cystic duct. 110This possible means of conducting current was suggested by the appellant in his letter of 3 March 2009 to Dr Whitehead. At that time, the appellant's opinion was that this possibility was more likely than the diathermy electrode having come into contact with a surgical clip during the surgery. By contrast, during cross-examination, the appellant said that both possibilities were about equivalent. 111The appellant submitted that the location of the stricture in the respondent's common hepatic duct was equally consistent with the conduction of current down the hepatic artery to the point where the stricture occurred in the respondent's common hepatic duct. The appellant's evidence was that the hepatic artery was in the "same general area" as the clips on the cystic duct. The possibility of the current travelling down the hepatic artery was said to arise because it is unpredictable how far a current may pass down a vessel. 112There are a number of reasons why the trial judge was entitled to exclude this possible explanation. First, the appellant's evidence was that "it's unlikely but not impossible" that the diathermy was applied in some other position resulting in conduction of current down the hepatic artery to the point where the stricture occurred in the respondent's common hepatic duct. 113Secondly, the appellant's evidence that the usual technique he followed was to keep the diathermy current well away from the right hepatic artery was inconsistent with this possible explanation. Nor did the appellant suggest that he in fact deployed the diathermy current in this location in the present case. 114Thirdly, there was no evidence of any damage to the respondent's right hepatic artery, notwithstanding the extensive post-operative search for any explanation of the respondent's stricture. This is significant because the diathermy current produces heat when applied to tissue and the absence of evidence of any damage to the hepatic artery is consistent with the diathermy current not having come into contact with, let alone travelling through, this artery. 115Fourthly, the trial judge correctly noted the degree of imprecision in the appellant's evidence that the right hepatic artery was in the "same general area" as the clips attached to the cystic duct. In this regard, the appellant's oral closing submissions before the trial judge acknowledged that there was no evidence of the proximity between the stricture in the respondent's common hepatic duct and the right hepatic artery. 116In addition, the trial judge was correct to observe that there was an absence of evidence on certain issues raised by cause 4 (see [74] above) which militated against acceptance of conduction of current through the right hepatic artery as an equally possible explanation of the respondent's stricture. 117In my view, no error has been shown in the trial judge's exclusion of cause 4 as a possible explanation of the respondent's stricture.

Cause 5 118This involved the possible application of the diathermy too close to the respondent's bile duct so as to cause a burn. It had been suggested by Dr Drew in his report dated 7 July 2011 and during his concurrent evidence when suggesting that the "flow void" on the operative cholangiogram might have been due to "blistering" caused by a burn to the bile duct. The trial judge excluded this possibility, having accepted that the evidence was against a burn to the bile duct. A burn would not cause a stricture, but rather would cause a hole in the duct. No complaint is made by the appellant in this regard. It requires no further consideration.

Cause 6 119This possibility involved some other unknown cause related to the procedure itself. It was first raised by the appellant during the trial. It was not given as a possible explanation in the appellant's 3 March 2009 letter to Dr Whitehead, which was contemporaneous with having examined the respondent and reviewed the CT cholangiogram and report of Dr Ketheswaran obtained in February 2009. 120In support of this possibility, the appellant gave evidence that a number of different factors might provide the mechanism for bile duct injuries of the type suffered by the respondent in the present case. These included abnormal anatomy, abnormal biliary anatomy and variations of biliary and/or vascular anatomy. The appellant complains that this evidence and the possibility of cause 6 being the explanation for the respondent's injury, was not addressed by the trial judge. 121In my view, this complaint is unfounded. First, there was no evidence before the trial judge that the respondent's anatomy was abnormal, or that the appellant experienced any operative difficulties with the respondent's anatomy at the time of the surgery. 122Secondly, the trial judge correctly observed that the appellant's suggestion that the cause of the stricture must have been some other unknown cause related to the procedure itself was not advanced in his letter of 3 March 2009. It was only advanced in the context of the appellant having agreed in cross-examination that the most likely explanation for the stricture was that it arose from the surgery carried out by the appellant, and that one possible explanation in that regard was that the diathermy current had been inappropriately applied where it should not have been applied. 123The appellant's suggested explanation was not based on any facts specific to the respondent or the operation which the appellant had performed. Rather, it reflected an attempt by the appellant to rationalise how the stricture could have occurred during the operation, on the implicit assumption that the diathermy current was not inappropriately applied during the operation. 124In my view, the appellant has not demonstrated that trial judge fell into error in excluding cause 6 as an equally likely cause of the respondent's stricture.

Cause 3 125The trial judge found that the stricture in the respondent's common hepatic duct was caused by the application of the diathermy at or near the surgical clip attached to the respondent's cystic duct. In fact, there were three surgical clips attached to the cystic duct adjacent to the common hepatic duct where the stricture was later identified. 126This possibility had been raised by the appellant in his letter to Dr Whitehead of 3 March 2009, in his oral evidence and in the reports of Dr Drew (the respondent's expert). 127The appellant submits that the trial judge's conclusion on causation was not supported by the three matters relied upon by the trial judge for accepting cause 3. These were the "immediate proximity" of the stricture at the location of the surgical clip, the evidence of Dr Drew and the evidence of the appellant. Each of these matters is considered below.

(a) Location of the stricture 128The primary judge found, based on the medical evidence, that the location of the respondent's stricture was in the immediate proximity to the surgical clip attached to the cystic duct during the operation. There is no challenge to this finding. 129However, the appellant submitted that the trial judge did not appear to have taken into account the evidence of the appellant that the location of the stricture in the location of the surgical clips, was equally consistent with cause 4 (ie, conduction of current down the right hepatic artery), and the appellant's evidence was not contradicted by either of the experts. 130Contrary to the appellant's submission, the trial judge did consider the appellant's evidence concerning the location of the stricture in proximity to the right hepatic artery when considering cause 4 (conduction of current down the right hepatic artery). The highest the evidence went was that the right hepatic artery was in the "same general area" as the respondent's stricture (see [115] above). Viewed in the light of the reasons given above for concluding that the trial judge correctly excluded cause 4, this evidence does not establish error in the trial judge's acceptance of cause 3.

(b) Dr Drew's evidence 131 The appellant submitted that the trial judge erred in relying on Dr Drew's hypothesis of a diathermy burn by direct contact of the diathermy with the bile duct (cause 5), when rejecting Dr Hugh's opinion in support of cause 2, that the respondent's stricture was a pre-existing idiopathic benign stricture. The premise underlying this submission is incorrect. The trial judge did not accept Dr Drew's hypothesis that the diathermy had touched the bile duct causing a diathermy burn. 132However, Dr Drew's evidence was not limited to the possibility of a diathermy burn. His evidence, which it was open to the trial judge to accept, was that the respondent's stricture resulted from the duct being damaged, directly or indirectly, by use of the diathermy either too close to the common bile duct, or actual contact of the diathermy with the surgical clips. The trial judge excluded the former possibility when rejecting cause 5, and correctly observed that Dr Drew's alternative explanation that the injury was caused due to the actual contact of the diathermy with the surgical clips was not challenged in cross-examination. 133It is apparent that in rejecting Dr Hugh's opinion in support of cause 2, the trial judge placed reliance on Dr Drew's opinion concerning contact of the diathermy with the surgical clips. The trial judge rejected the alternative explanation proffered by Dr Drew concerning use of the diathermy too close to the common bile duct causing a diathermy burn. There is no error disclosed in this reasoning of the trial judge.

(c) Appellant's evidence 134The appellant agreed in cross-examination that temporally the most likely explanation for the stricture in the respondent's common hepatic duct is that it arose from the surgery he had carried out. He rated the probabilities of a current through the hepatic artery or a current through the clip as being both about equivalent. 135The appellant's other possible explanations, namely a pre-existing condition known as PSC, or some other unexplained cause related to the procedure, may both be ignored for the reasons given above in relation to cause 1 and cause 6 respectively. 136As to the explanation based on conduction of a current through the hepatic artery, the appellant expressed the view that this was always a possibility because it is unpredictable how far a current will go in given circumstances. Somewhat inconsistently, he said that the technique which he followed kept the diathermy current well away from the right hepatic artery. Further, he did not suggest that he deployed the diathermy current in the present case, anywhere near the location of the right hepatic artery. He agreed that this explanation involved "some very odd chemical nature of the [respondent's] body" for the conduction of electricity further than had occurred in any other patient. He did not explain how this "odd" conduction of current could have occurred, or why the heat from the current would not have damaged the respondent's hepatic artery if the diathermy had been applied in that location. He also agreed that the likelihood of this explanation was "very low" and "unlikely but not impossible". 137As to the alternate explanation of a current through the clip, the appellant was emphatic that there was no possibility that he had departed from his usual technique such that he had passed the diathermy current directly to the surgical clips. His evidence was that it was "just impossible" that he lapsed from his invariable practice and got the diathermy in the wrong position. 138The appellant disagreed with the suggestion in cross-examination that the immediate proximity of the clips to the stricture in the respondent's common hepatic duct suggested that the more likely path of the current was through the clips. The reason he gave why this was "not necessarily" more likely was because the right hepatic artery was in the "same general area" as the respondent's stricture. He also noted that the "filling void" (which he attributed to the right hepatic artery) shown on the cholangiogram taken during the operation before the cystic duct was dissected, was exactly where the clips were placed on the cystic duct. 139In my view, the appellant's evidence concerning the possibility of conduction of current through the hepatic artery was inherently speculative, and suffered from the problems identified above when considering cause 4. 140By contrast, the alternate explanation (current through the clip) did not suffer from the unexplained difficulties of some "odd" conduction of current through the hepatic artery, but without damage to the artery itself. The appellant acknowledged that applying the diathermy current too close to the clips gave rise to a risk of a bile duct injury. This could occur because the clips transmitted the current and hence the heat to the adjacent duct. The appellant's only reason for rejecting this as the likely cause of the respondent's injury was his assertion (in his own interest) that he simply would not have applied the diathermy in the wrong position. 141In my view, the appellant has failed to establish that the trial judge erred in his conclusion on the cause of the respondent's stricture. It follows that ground 2 of the notice of appeal has not been made out.

Breach of duty (grounds 3, 4 and 5) 142The question of breach of duty is to be considered by reference to the relevant provisions of the Civil Liability Act, in particular s 5B (see Adeels Palace Pty Ltd v Moubarak at 437 [27]). 143The "risk of harm" to which s 5B(1) refers is harm that might be suffered by anyone to whom the defendant owes a duty of care, as a consequence of the failure to take the precautions referred to in s 5B(1). Section 5B requires risks to be assessed prospectively (see Sibraa v Brown [2012] NSWCA 328 at 41 per Campbell JA (Hoeben JA and Tobias AJA agreeing)). 144It may be taken from the appellant's admission on the pleadings of his awareness of the necessity to avoid injury to the common bile duct during the use of the diathermy electrode, that there was a risk of which the appellant knew (s 5B(1)(a)) that a diathermy injury may result from the application of the current too close to the surgical clips or the common bile duct. 145It may also be taken based on the evidence of the appellant and Dr Drew that this risk of harm was "not insignificant" (s 5B(1)(b)). The standard for a risk being "not insignificant" is not particularly high and, in my view, is well satisfied in the present case (see Shaw v Thomas [2010] NSWCA 169 at 44 per Macfarlan JA (Beazley and Tobias JJA agreeing); Sibraa v Brown at [49]). 146The question is whether a reasonable person in the position of the appellant would have taken the precautions that the respondent alleged should have been taken (s 5B(1)(c), s 5B(2)). Those precautions were said to be not to bring the diathermy electrode (when active) too close to the common bile duct or the surgical clips attached to the cystic duct. 147Whether the appellant should have avoided the application of the diathermy in this manner to satisfy his duty to take reasonable care depended upon the considerations identified in s 5B(2) of the Civil Liability Act: the probability that the harm would occur, the likely seriousness of the harm, the burden of taking precautions to avoid the risk, and the social utility of the activity that created the risk. In this case the main focus is on the first three of those considerations. 148First, there was a high probability that harm would result if the appellant did not take care in the use of the diathermy. Secondly, if harm were to arise from the use of the diathermy too close to the common bile duct or the surgical clips, it was likely that anyone who suffered injury as a consequence would suffer harm of a serious nature. 149Thirdly, as to the burden of taking precautions to avoid the risk of harm, this matter is largely subsumed in the appellant's submissions that the trial judge erred in finding that the respondent's injury was not a "normal risk" of surgery and also erred in rejecting the expert medical opinions on the ultimate issue. The appellant's submissions in support of these contentions are considered below. As to the final consideration, no issue arose as to the social utility of the activity that created the risk of harm. The appellant did not suggest any other factors were applicable in the present case.

Trial judge's reasons 150As noted above, the trial judge's reasons on breach of duty are quite brief. The trial judge found that cause 3 (application of the diathermy at or near the surgical clips) was not a "normal risk" of surgery, that there had been a departure by the appellant in this case from the usual degree of diligence he applied when using the diathermy, and he rejected the evidence of Dr Hugh, Dr Drew and the appellant that there was no departure from the required standard of care in this case. 151In reaching this conclusion, it is apparent that the trial judge had regard to the appellant's failure when identifying the normal risks of the procedure to include the risk of diathermy injury; the appellant's evidence of his practice of pointing out to registrars the risk of using the diathermy current too close to the surgical clips; the appellant's evidence as to the potentiality of injury should the diathermy current come too close to the surgical clips; and the appellant's evidence of his usual technique when performing a laparoscopic cholecystectomy, which was to avoid the use of the diathermy in the location of the clips or the common bile duct. 152In rejecting the expert evidence of Dr Drew and Dr Hugh, given concurrently, that they each had no reason to believe that there had been any negligence on the part of the appellant, it is apparent that the trial judge had regard to the very general terms in which they gave evidence of the risk of bile duct injury, in particular, injury arising from diathermy burns.

Appellant's submissions 153The appellant submitted that even if cause 3 was established to be the cause of the stricture, the trial judge's conclusion on breach was not well founded. The appellant relied upon three particular matters:

• First, that the operation report dated 16 October 2009, did not refer to anything out of the ordinary having occurred during the course of the procedure.
• Secondly, the extensive number of similar operations carried out by the appellant during the course of his career and his evidence that he always exercised extreme caution to avoid using the diathermy anywhere near the surgical clips; that he had no reason to think or suspect that he had departed from this practice in the case of the respondent; and that the appellant denied that the presence of the common hepatic duct stricture indicated a departure from his usual technique.
• Thirdly, the evidence of the expert doctors.

Operation report 154As to the terms of the operation report, the absence of any reference to a possible bile duct injury during the operation is unremarkable having regard to the cause and nature of the diathermy injury to the respondent's common hepatic duct, as found by the trial judge. 155First, the evidence before the trial judge included the evidence of Dr Hugh and the appellant, that in the case of a diathermy burn to a bile duct producing a hole in the wall of the duct, there would be leakage of bile from the duct which would have been visible to the operating team. However, in this case, the diathermy injury to the respondent's common hepatic duct caused by application of the diathermy current at or near the surgical clips, did not produce a hole in the duct and there were no signs of the diathermy injury which would have been obvious to the appellant at the time of the operation. 156Secondly, there was no evidence below that the appellant would have noticed any momentary contact of the diathermy current at or near the surgical clips.

Departure from appellant's usual technique or method 157As to the appellant's evidence concerning his extensive past and continuing experience in performing similar operations, and that he had no reason to think or suspect that he had departed from his usual practice in this case, this needs to be weighed against the whole of his evidence. This evidence includes that he could not recall the actual operation; that he had acknowledged in his letter of 3 March 2009 to Dr Whitehead that one possibility was that the diathermy may have come in contact with the surgical clips during the course of the surgery (albeit he considered this less likely than conduction of current through the hepatic artery); that his alternative explanation of some "odd" conduction of current through the right hepatic artery was "unlikely but not impossible"; and that the most likely temporal explanation is that the respondent's injury occurred during the surgery. 158The critical part of the appellant's evidence was his explanation of his usual technique when carrying out a laparoscopic cholecystectomy. The appellant emphasised three matters. First, the technique the appellant followed did not involve dissection around the bile ducts, rather it involved dissection of the gallbladder off the liver to the cystic duct. He emphasised: "I don't actually dissect around the bile ducts or near the bile ducts with this technique. That's the main reason for that technique ... you keep away from the bile ducts." 159Secondly, and following on from the first matter which identified the location in the patient's anatomy where the diathermy was used, the appellant's usual technique did not involve the deployment of the diathermy close to the clips or close to the bile duct. 160Thirdly, the surgeon's discipline of following and adhering to this usual technique was part of the appellant's normal practice and normal care given to his patients. 161It is apparent that the occurrence of the harm to the patient's bile duct during the procedure was one of the very risks about which the appellant's usual technique or method was designed to avoid, by not using the diathermy current in the location of the surgical clips or close to the bile duct. The appellant did not suggest that there was any reason in this case, such as a variation in the respondent's anatomy, as to why the diathermy current should have been deployed in the region of the clips or the common hepatic duct. 162The deployment of the diathermy current at or near to the surgical clips as found by the trial judge, necessarily involved a departure from the appellant's usual technique. The question is whether such a departure was avoidable and the conduct in this case negligent. In my view, on the appellant's own evidence, the respondent's injury was avoidable because there was no reason why the diathermy current should have been deployed by him in that location. This is not a case where the surgeon was required to make a clinical judgment as to how close to the clips he should use the diathermy current and the question is whether there was an error of judgment which may or may not involve negligence (see Whitehouse v Jordan [1981] 1 All ER 267 at 276 and 281). This is a case where the appellant's evidence is that the usual technique he followed was not to use the diathermy in the location of the clips, and it was "just impossible" that he got the diathermy in the wrong position. However, the trial judge found that he had done so. In those circumstances, his conclusion of negligence in the deployment of the diathermy current has not been shown to be erroneous.

Expert evidence 163The appellant's submissions placed much reliance upon the evidence of the expert doctors, in particular, that given during the course of the concurrent evidence (see [55] to [63] above). 164The appellant's submissions acknowledged that the question of breach of duty is a matter for the Court, which is not bound by the opinion of the experts. It was submitted however that in the circumstances of this case the expert evidence should have had an influential, indeed a decisive role to play on the question of breach. See Rogers v Whitaker [1992] HCA 58; (1992) 175 CLR 479 at 487; Rosenberg v Percival [2001] HCA 18; (2001) 205 CLR 434 at 454. 165As explained above (at [162]), the factual inquiry concerning the technical performance of the laparoscopic cholecystectomy by the appellant involved a consideration of whether the deployment of the diathermy current at or near the surgical clips as found by the trial judge, was avoidable by the exercise of reasonable care or was something less, being an unavoidable risk of the procedure. The inquiry did not involve expert opinions as to the appropriate clinical judgment concerning how close to the clips the surgeon should use the diathermy current. The appellant and Dr Drew were agreed that the diathermy current should not be deployed near the surgical clips, though Dr Hugh did not specifically address this issue. The inquiry, in this case, was somewhat more stark than the general evidence given by the experts concerning the possibility of bile duct injuries during a laparoscopic cholecystectomy, including diathermy injury. The inquiry was whether the deployment of the diathermy current such that it came into contact, or in very close vicinity of the clip, was an error which was avoidable by the exercise of reasonable care. 166In my view, the trial judge was entitled to reject the expert evidence on the ultimate issue and reach his own conclusion on the question of breach of duty of care. My reasons are as follows. 167First, the evidence of Dr Hugh in his report of 26 July 2011, that bile duct injury and stricture formation may happen to the most careful surgeon was expressed in only general terms by reference to a variety of possible causes of such injuries, only one of which included the use of diathermy instruments. Dr Hugh's report did not address the specific mechanism of the diathermy injury in the present case, as found by the trial judge. This is not surprising as Dr Hugh did not consider that any injury occurred during the operation on the respondent. 168Secondly, insofar as Dr Hugh pointed to the widely expressed view in the medical literature that the risk of bile duct injury and stricture formation may happen to the most careful surgeon when the operation is being conducted with all due care, the chief focus of this literature was misperception errors by the surgeon concerning the patient's anatomy, which included injuries resulting from a dissection too close to the common hepatic duct. This literature is of little assistance in the present case, because the appellant's usual technique did not involve dissection (by use of the diathermy) in the location of the cystic duct or the common hepatic duct, and there is no suggestion by the appellant of any misperception issue when carrying out the procedure. 169Further, the medical literature tendered at the hearing did not address the specific issues of either the use or unpredictability of the diathermy current in laparoscopic procedures, or injuries to the common hepatic duct resulting from current transmitted through the clips attached to the cystic duct. The class II type injuries (consisting of lateral damage to the common hepatic duct that produced a stricture and/or fistula formation) referred to the article by Dr Way and others (published in the Annals of Surgery in April 2003), were described as follows: "These injuries usually involve the placement of clips on the duct in conjunction with cautery damage during attempts to control bleeding (23%) or as a result of poor exposure (68%). Class II injuries never completely transected or occluded the CHD; they involved severe lateral damage leading to stricture formation (with or without a bile leak)." In the present case the respondent's injury was not a consequence of the incorrect placement of the clips on the common hepatic duct leading to bleeding which the appellant attempted to control by cauterization, nor poor exposure, that is, difficulty in identifying the respondent's ductal anatomy before dissecting the cystic duct from the gallbladder. 170Later the same article explained that: "In the class II ...injuries, the mistake consisted of performing the dissection in the triangle of Calot unintentionally too close to the bordering common hepatic or right hepatic duct. The ducts were not seen because they were covered by connective tissue or inflammation. The underlying nature of the error in either case was misperception." It will be observed however, that the appellant's usual technique for this procedure was developed to avoid the type of misperception problem referred to by these authors, when performing the dissection of the gallbladder off the liver. 171For the same reason, the conclusion expressed by Way and others that: "... the usual misperception error underlying laparoscopic bile duct injuries does not meet the defining criteria of medical negligence", has no application to the present case. It is not suggested by the appellant that there was any misperception of the respondent's ductal anatomy resulting in a dissection of the cystic duct too close to the common hepatic duct. Moreover, the dissection of the cystic duct, according to the appellant, did not involve the use of the diathermy instrument. A different cutting instrument was used by the appellant. 172Thirdly, Dr Hugh's oral evidence went no higher than that he did not agree that the respondent's injury "must" have been caused by a want of skill and care by the surgeon. As the trial judge correctly observed, Dr Hugh's oral evidence was in very general terms. His evidence did not address the usual technique followed by the appellant when performing laparoscopic cholecystectomies, in particular, that the diathermy current was not deployed in the location of the clips attached to the cystic duct or the common hepatic duct. 173Fourthly, Dr Drew's agreement with the cross-examiner's proposition that it was well known in the medical literature and by the experience of surgeons that even the best of surgeons using the best technique are subject to the risk of a diathermy burn in this particular type of surgery, was also given in only very general terms. 174Fifthly, Dr Drew's evidence concerning the unpredictability of diathermy, is not to be taken as evidence that the particular injury in this case was unavoidable. This is because the mechanism of the respondent's injury, as found by the trial judge, did not depend on the unpredictability of the diathermy current, but rather the deployment of the diathermy in the location which the appellant conceded would have been the "wrong position", and which the appellant knew must be avoided to avoid the possibility of conduction of current through the clips to the bile duct. 175Sixthly, the trial judge was entitled to find on the appellant's evidence that a bile duct injury caused by the diathermy current coming in contact with, or close vicinity to, the clip, was not a normal risk of surgery. The appellant's failure to include such risk as a normal risk of surgery is an implicit acknowledgment that the injury in this case was avoidable.

Whether the risk of injury could have been avoided 176The appellant also submitted that the respondent had not proved, on the balance of probabilities, that the risk of the type of injury suffered by the respondent was one that could have been avoided rather than just minimised, by the exercise of due care and skill (ground 4). 177It was further contended by the appellant that the trial judge should have found that this case fell into a recognised but small category of cases in which injuries of this type occur, due to unpredictability of the diathermy, variations in anatomy or some other unknown case, without any want of due care on the part of the surgeon. 178These submissions should be rejected. First, once it is accepted that the mechanism of the respondent's injury was the deployment of the diathermy current in the location found by the trial judge, it was not erroneous for the trial judge to find on the appellant's evidence concerning the usual technique he followed for the procedure, that the risk of injury could have been avoided, not just minimised by the exercise of due care and skill. As the appellant made clear in explaining the use of the diathermy current when performing the procedure: "You just don't do what you shouldn't do". 179Secondly, the appellant's reference in his evidence to the unpredictability of the diathermy current is not to the point, once there was a finding that the cause of the respondent's stricture was that the diathermy was deployed by the appellant at or near the clips. The possibility of the clips conducting current to the duct is the very risk the appellant was addressing when instructing registrars not to diathermy near the clips. The mechanism of the injury as found by the trial judge, did not involve the unpredictability of the diathermy current. 180Thirdly, there was no evidence of variations in the respondent's anatomy, which might explain the injury suffered during the procedure (see [120]-[121] above). 181Fourthly, the appellant's reference to some other unknown cause related to the procedure is entirely speculative (see [122]-[123] above). It is also inconsistent with the trial judge's factual finding as to the cause of the respondent's stricture. 182In the circumstances, I am satisfied that the trial judge's approach to the issue of negligence was appropriate. The respondent had established that in this case, the injury was caused in an area other than where the diathermy current should have been deployed. The appellant agreed that this location was the "wrong position" to deploy the diathermy. The usual technique followed by the appellant involved the use of the diathermy at a location distant from the clips and the common hepatic duct. The respondent's injury was avoidable if the appellant had maintained the discipline of following his usual technique. The appellant's departure from this discipline did not involve a clinical judgment as to how close to the clips he should deploy the diathermy. Rather, it was a departure from the usual standard of care expected of the ordinary skilled person exercising and professing to have that special skill of a surgeon in the position of the respondent in the conduct of the procedure.

Materialisation of inherent risk 183The appellant made a related submission that a diathermy injury to the common bile duct during a laparoscopic cholecystectomy was an "inherent risk" of the surgery. This was because it was said to be a matter of judgement about which there can be no correct answer necessarily as to whether the diathermy electrode was applied too close to the surgical clips so as to cause an injury to the bile duct. The appellant referred to the statement of Tobias JA in Wyong Shire Council v Vairy [2004] NSWCA 247; [2004] Aust Torts Reports ¶81-754 at 65,892-65,901 [163]-[165], [167], [205]-[209], [212], which was referred to with approval by the High Court in Mulligan v Coffs Harbour City Council [2005] HCA 63; (2005) 223 CLR 486 at 506 [72], that an "inherent danger" is a danger (or risk) attaching to a condition or activity that cannot be removed by the exercise of due care. 184The appellant acknowledged that his submissions concerning "inherent risk" were to be understood in the context of s 5I of the Civil Liability Act, which provides that a person is not liable in negligence for harm suffered by another person as a result of the materialisation of an inherent risk (s 5I(1)). 185An "inherent risk" is a risk of something occurring that cannot be avoided by the exercise of reasonable care and skill (s 5I(2)). Whether or not a risk is an "inherent risk" will be a question of fact in each case. 186The purpose and effect of s 5I of the Civil Liability Act was considered by Brereton J in Paul v Cooke [2012] NSWSC 840 at [109]-[122]. Strictly, his Honour's views were obiter, having regard to the conclusion reached in that case in respect of causation. Relevantly, Brereton J expressed the view that s 5I does not create a defence and no question of onus arises. 187No submissions were made by the parties on the issue of whether s 5I creates a defence and the question of onus of establishing that the injury was the materialisation of an inherent risk. It is unnecessary to consider the question of onus in this case, or the correctness of the views of Brereton J's in Paul v Cooke, having regard to the conclusions reached above. 188In my view, the appellant's characterisation of the respondent's injury as an inherent risk that could not be avoided in this case, should not be accepted. 189First, it is the occurrence (not the risk of it) that must be unavoidable by the exercise of reasonable care and skill. This accords with the focus of s 5I(1) being not the risk, but its materialisation (see Paul v Cooke at [120] per Brereton J). 190Secondly, the occurrence of the diathermy injury in this case was, on the appellant's evidence, avoidable by the exercise of reasonable care and skill. This was because the usual technique which the appellant followed avoided the deployment of the diathermy at or near the clips, or the common bile duct. 191Thirdly, the appellant's evidence that it was "just impossible" that he got the diathermy in the "wrong position", is also inconsistent with the proposition that the occurrence of the injury was the materialisation of an inherent risk of the procedure. 192For the above reasons, grounds 3, 4 and 5 of the notice of appeal have not been made out.

Conclusion 193In my view, the appellant has not shown error in the trial judge's conclusions on either the cause of the respondent's stricture, or the appellant's breach of his duty of care. I propose the following orders: (1)Appeal be dismissed. (2)Appellant to pay the respondent's costs.

DISCLAIMER - Every effort has been made to comply with suppression orders or statutory provisions prohibiting publication that may apply to this judgment or decision. The onus remains on any person using material in the judgment or decision to ensure that the intended use of that material does not breach any such order or provision. Further enquiries may be directed to the Registry of the Court or Tribunal in which it was generated. Decision last updated: 09 July 2013