Benign biliary tract diseases

Biliary atresia

Biliary atresia occurs in approximately 1 per 10 000 live births, but its aetiology remains unclear. There is experimental evidence for a primary perinatal viral infection as well as cellular and humoral autoimmunity. An inflammatory process before birth may result in failure of the biliary lumen to develop in all or part of the extrahepatic biliary tree. Several clinical variants are thought to originate during intrauterine development with different outcomes from surgical hepatic portoenterostomy. Around 80% have an isolated form which includes a cytomegalovirus variant. A congenital malformation accounts for 10–20% and this includes a biliary atresia malformation syndrome (BASM) and cystic biliary atresia (CBA).

Presentation is usually in the early neonatal period with prolongation of neonatal jaundice. Most patients are treated in specialist neonatal surgical units; however, occasionally patients may be referred to adult units for assessment for liver transplantation following previous unsuccessful treatment. Management in the neonate is by surgical porto-enterostomy (Kasai procedure), which involves anastomosis of a Roux limb of jejunum to the tissue of the hilum. Restoration of bile flow has been reported in 86% of infants treated before 8 weeks of age, but only 36% in older children. The 4-year survival rate is dependent on the timing of surgery. Of 349 North American children with biliary atresia, 210 (60%) required later liver transplantation, with a 4-year transplantation survival of 82%. A properly performed Kasai porto-enterostomy can postpone the need for liver transplantation and improve outcome. Better outcomes are also seen following maternal living donor-related liver transplantation, potentially due to tolerance to non-inherited maternal antigens.

Choledochal cysts

Presentation is usually in childhood, with jaundice, fever or an abdominal mass. Around 25% are diagnosed in the first year, although prenatal diagnosis is usually possible with improvements in antenatal ultrasonography. Adult centres treat a small proportion of those presenting with late symptoms or complications from previous cyst surgery.

The incidence of choledochal cysts in Western countries is around 1 in 200 000 live births, but it is much higher in Asia. There is frequent association with other hepatobiliary disease such as hepatic fibrosis, as well as an aberrant pancreaticobiliary duct junction. Magnetic resonance cholangiopancreatography (MRCP) is the non-invasive imaging investigation of choice ( Fig.13.1 ).

Classification

The modified Todani classification is employed to describe the various forms of choledochal cyst ( Fig. 13.2 ). Type I, the most common, represents a solitary cyst characterised by fusiform dilatation of the common bile duct (CBD). Type II comprises a diverticulum of the CBD, whilst type III cysts are choledochocoeles. Type IV is the second most common, with extension of cysts into the intrahepatic ducts. Lastly, type V involves intrahepatic cystic disease with no choledochal cyst, which merges into the syndrome of Caroli disease.

Special operative techniques

During operative exposure, intraoperative ultrasound is very useful to identify the biliary confluence, the intrahepatic extension of the cyst and the relationship to the right hepatic artery above and to the pancreatic duct below ( Fig. 13.3 ). Small aberrant hepatic ducts may enter the cyst below the biliary confluence and these are missed frequently on preoperative imaging. Such aberrant ducts are usually identified once the cyst has been opened. The uncomplicated cyst is normally best excised in its entirety and this is facilitated by opening it along its anterior length. This aids identification of the vessels from which the cyst is fed. Early identification of the biliary confluence aids the surgeon in planning the incorporation of any segmental duct into the eventual hepaticojejunal Roux-en-Y anastomosis. Dissection into the head of the pancreas is made easier by use of bipolar scissors and the CUSA™ (ultrasonic surgical aspiration system, ValleyLab, Boulder, CO) if the plane of dissection is obscured by fibrosis or inflammation. It may be necessary to leave a small oversewn lower CBD stump to avoid compromise to the pancreatic duct lumen; however, recurrent pancreatitis and possible malignant transformation remain possible complications. Pancreaticoduodenectomy is difficult to justify in the uncomplicated case when dealing with the residual lower bile duct. Laparoscopic and robotic resection and reconstruction have been described; Senthilnathan et al. reported 110 adults and children successfully managed, with three adults requiring conversion, a re-exploration rate of 1.8% and one death. Cholangitis occurred in three patients, with three requiring intervention for anastomotic strictures on the short-term follow-up. (See recommended video at the end of chapter.)

There is an accepted association between choledochal cyst and cholangiocarcinoma. The cyst should be excised and the biliary tree reconstructed by means of a Roux-en-Y hepaticojejunostomy.

Aetiology

Previous reports of injury during laparoscopic cholecystectomy suggested that injury was more likely to occur when performed for pancreatitis, cholangitis or acute cholecystitis. However, surgeons should remain vigilant regardless of the indication. In the majority of patients the problem is misinterpretation of the biliary anatomy, with the CBD being confused with the cystic duct. Associated injury to the right hepatic artery often occurs as it is mistaken for the cystic artery. Partial injury may occur to the CBD after a diathermy burn or due to rigorous traction on the cystic duct, leading to its avulsion from the bile duct.

Techniques to avoid injury

Many techniques have been described to decrease the risk of injury to the CBD during cholecystectomy. The main risk factors are thought to be inexperience, aberrant anatomy and inflammation. ^, However, in an analysis of 252 laparoscopic bile duct injuries, the authors suggested that the primary cause of error was a visual perceptual illusion often resulting in loss of situational awareness in 97% of cases, whilst faults in technical skill were thought to have been present in only 3% of injuries.

Correct identification of the biliary anatomy is essential in avoiding injury to the extrahepatic bile duct. Dissection of Hartmann’s pouch should start at the junction of the gallbladder and cystic duct and continue lateral to the cystic lymph node, thus staying as close as possible to the gallbladder. The biliary tree and hepatic arterial anatomy is highly variable and therefore great care must be taken in identifying all structures within Calot’s triangle before ligation. In Couinaud’s published study of biliary anatomy, 25% had drainage of a right sectoral duct directly into the common hepatic duct. Sometimes this structure may follow a prolonged extrahepatic course, where it can be at greater risk from cholecystectomy ( Figs. 13.4 and 13.5 ). The right hepatic artery may also course through this area. All structures should be traced into the gallbladder to minimise the risk of injury.

Calot’s original description of gallbladder anatomy described a triangle formed by the cystic duct, common hepatic duct and superior border of the cystic artery. For satisfactory visualisation of the structures, dissection should also extend above the cystic artery to the liver. Extensive dissection should be avoided in Calot’s triangle as diathermy injury may occur to the lateral wall of the common hepatic duct. Furthermore, arterial bleeding in this area should not be cauterised or clipped blindly. Most bleeding can be controlled with several minutes of direct pressure with a laparoscopic forceps compressing Hartmann’s pouch on to the bleed point. During the era of open cholecystectomy, many advocated complete excision of the cystic duct to its insertion into the CBD to avoid a cystic duct stump syndrome. However, extensive dissection around the CBD with or without diathermy may cause an ischaemic stricture due to damage to the intricate blood supply of the common hepatic duct.

Strasberg described the ‘critical view of safety’ with complete dissection of Calot’s triangle by mobilisation of the gallbladder neck from the gallbladder bed of the liver before transecting the cystic artery and duct. More recently, Connor et al. suggested a five-point checklist to limit the occurrence of biliary injury at laparoscopic cholecystectomy. The five steps are: ‘(i) confirm the gallbladder lies in the hepatic principal plane and is retracted to the 10 o’clock position; (ii) confirm Hartmann’s pouch is lifted up and towards the segment IV pedicle; (iii) identify Rouviere’s sulcus; (iv) confirm the release of the posterior leaf of the peritoneum covering the hepatobiliary triangle; and (v) confirm the critical view with or without intraoperative cholangiography’.

Many authors argue that operative cholangiography is essential to avoid biliary injury. ^, Fletcher et al. reported an overall twofold reduction in biliary injuries with the use of operative cholangiography, with an eightfold decrease in complex cases. Flum et al. analysed retrospectively the Medicare database in the USA and identified 7911 CBD injuries following cholecystectomy. After adjusting for patient-level factors and surgeon-level factors, the relative risk was 1.49 when intraoperative cholangiography was not used. In a recent meta-analysis of 2 million cholecystectomy patients, 9000 bile duct injuries were included. The rates of bile duct injury were 0.36% when cholangiography was used routinely and 0.53% when used selectively.

When the use of intraoperative cholangiography has undergone cost analysis, routine cholangiography has been found to be most cost-effective during high-risk operations when employed by less experienced surgeons.

Unfortunately, many operative cholangiograms are interpreted incorrectly and injuries are missed. Although this event should be less frequent with the use of modern C-arm imaging, in reported series of biliary injuries only 6–33% of operative cholangiograms are interpreted correctly. For correct anatomical interpretation of the proximal biliary tree, both right sectoral/sectional ducts and the left hepatic duct should be visualised. In the presence of an endoscopic sphincterotomy, contrast will preferentially flow into the duodenum and the patient may need to be placed in a head-down position to fill the intrahepatic ducts. If the anatomy is unclear, no proximal clip should be placed on what is presumed to be the cystic duct, to avoid a crush injury to what may be the common hepatic duct.

Retrograde cholecystectomy has been described previously as a safe technique when inflammation around Calot’s triangle makes identification of the anatomy difficult. Nonetheless, care still needs to be exercised during dissection to avoid injury to the right hepatic artery and common hepatic duct, which may be adherent to an inflamed gallbladder. Eight such vasculobiliary injuries were described by Strasberg and Gouma. If identification remains impossible, then the gallbladder can be opened to facilitate identification of the cystic duct. A subtotal cholecystectomy should be considered if a safe plane of dissection cannot be established, thus avoiding injury to the common hepatic or left hepatic ducts. Originally described for open cholecystectomy, these techniques have now also been performed laparoscopically.

Classification

Injury to the distal biliary tree is less technically demanding to repair than involvement of the biliary confluence. The success of reconstruction depends on the type of injury and the anatomical location. Bismuth first described a classification system for biliary strictures reflecting the relationship of the injury to the biliary confluence ( Table 13.1 ). Strasberg et al. further proposed a broader classification to include a number of biliary complications, including cystic stump leaks, biliary leaks and partial injuries to the biliary tree ( Fig. 13.6 ). Recently the European Association for Endoscopic Surgery (EAES) has proposed the ATOM (anatomic, time of detection, mechanism) classification to facilitate epidemiologic and comparative studies.

Presentation

It is preferable that injuries are recognised at the time of surgery to allow the best chance of repair, but this occurs in less than a third of patients. An unrecognised injury may present early with a postoperative biliary fistula, symptoms of biliary peritonitis or jaundice. Early symptoms or signs may be lacking, but ductal injury should be suspected in the patient whose recovery is not immediate or is complicated by symptoms of peritoneal or diaphragmatic irritation and/or associated with deranged liver function tests in the first 24–48 hours of surgery. Signs may range from localised abdominal tenderness through to generalised peritonitis with overwhelming sepsis. Ligation of the bile duct will present early with jaundice; however, later presentation may occur as a result of stricture formation from a partial injury, localised inflammation or ischaemic insult.

Ligation of sectoral ducts may cause subsequent or late atrophy of the drained liver segments. Occasionally liver resection or transplantation may be required for unilobar hepatic necrosis or fulminant hepatic failure secondary to combined biliary and vascular injuries. More commonly, liver failure presents late with liver failure due to secondary biliary cirrhosis as a result of the injury, and may require liver transplantation.

In many patients there is a delay in referral despite suspicion or evidence of a biliary injury. In a report by Mirza et al., the median interval until referral was 26 days. This delay is not inconsequential as the opportunity for an early repair is lost and may result in the liver sustaining further damage.

Management