IATROGENIC BILE DUCT INJURIES - A PRACTICAL APPROACH

DR. R KRISHNAN

Iatrogenic injury to the biliary tree is a well documented complication of cholecystectomy with a reported rate of about 0.4-0.8% in most series. The advent of laparoscopic cholecystectomy and its sudden and widespread implementation in the early 1990's led to a dramatic increase in the frequency of biliary injury but with experience, the incidence of this complication has declined substantially. Bile duct injuries are best managed by a multidisciplinary team approach incorporating biliary endoscopists, interventional radiologists, and hepatobiliary surgeons. The management itself is guided by the nature and extent of the injury, the presence or absence of biloma, and the timing of discovery.

Anatomically, bile duct injuries may be classified using the Bismuth classification but for practical purposes, biliary tract injuries can be broadly divided into two groups:
- Bile leak without significant bile duct damage
- Major biliary tract injury with or without bile leak

It is important to appreciate that several injuries, particularly complex hilar lesions or total transections, are usually not amenable to endoscopic treatment and early referral for surgical intervention is prudent.

BILE LEAK
Minor and clinically insignificant or inapparent bile leaks are common after cholecystectomy. Such leaks are usually due to the necessary surgical division of small cholecystohepatic ducts (the ducts of Luschka) and the majority of these resolve without intervention or sequelae.

Significant postoperative bile leaks occur in approximately 0.8 to 1.1% of patients.

Diagnosis - Patients with bile leaks usually present within the first postoperative week although presentation may be delayed for up to 30 days. Minor bile duct leaks are associated with low output through a surgical drain and usually resolve without intervention. Persistent bile discharge from an operatively placed drain associated with pain and fever together with varying degrees of distension, ileus, and jaundice are hallmarks of a significant leak.

The diagnosis can usually be confirmed with an ultrasound but negative imaging does not preclude the possibility of a clinically significant leak.

Endoscopic cholangiography can delineate the site of the leak in over 95% of patients. It may also reveal the presence of stones and strictures.

Bile leaks can be classified into two groups based upon their cholangiographic magnitude:
- High grade leaks - there is rapid extravasation of contrast from the biliary tree upon initial injection with negligible intrahepatic filling
- Low grade leaks - require complete or near complete intrahepatic filling to demonstrate contrast extravasation

The cystic duct remnant is the site of bile extravasation in approximately 70% of cases, while ducts of Luschka account for about 6 to 17%. The common bile duct, common hepatic duct, and T tube tracts account for the remainder.

Endoscopic therapy - The goal of endoscopic therapy is to eliminate the transpapillary pressure gradient, thereby permitting preferential transpapillary bile flow rather than extravasation at the site of the leak. Prior to endoscopy, all patients should receive prophylactic broad spectrum antibiotics. The least invasive endoscopic approach possible should be used, which in most patients involves placement of a transpapillary stent without sphincterotomy. It is usually unnecessary to place a stent beyond the site of the leak although in practice this is often done. It is desirable to preserve the biliary sphincter wherever possible, particularly in young patients. Sphincterotomy will usually be necessary if a common bile duct stone is present. Low grade leaks occurring in the presence of a retained stone can usually be managed by sphincterotomy and stone extraction alone. In contrast, in patients with a high grade leak, it may be preferable to place a biliary endoprosthesis since sphincterotomy alone does not always totally eliminate the transpapillary pressure gradient.

Biloma - Bile leaks usually resolve quickly after placement of a stent. However, olacement of a stent will not aid in the reabsorption of an established biloma which should be drained percutaneously.

Outcome - Short-term placement of a biliary stent is definitive therapy for the vast majority of bile leaks that occur in the absence of additional biliary tract injury. In those without complications, stents can be removed after four to six weeks.

MAJOR BILIARY TRACT INJURY WITH OR WITHOUT BILE LEAK
Bile duct injuries are identified intraoperatively in up to one quarter of patients, although recognition of injury appears to be less frequent during laparoscopic compared to open cholecystectomy.

For patients with an unrecognized injury, the nature and timing of clinical presentation is variable and primarily influenced by the type of injury. The coexistence of a bile leak (from major duct disruption or complete transection) usually portends an early presentation whereas patients who develop strictures without bile leak have a significantly longer symptom free interval. The latter patients usually have signs of biliary obstruction (jaundice, cholestatic liver function tests, biliary dilatation on ultrasound).

Approach to the patient - Because of sepsis or peritonitis, the clinical status of the patient with an unrecognized biliary tract injury can deteriorate rapidly. Thus early diagnosis is imperative and imaging should not be delayed. Ultrasonography/CT will detect collections or biliary dilatation. Cholangiography is performed to define biliary anatomy. ERCP is preferred to percutaneous transhepatic cholangiography (PTC) due to its lower incidence of complications and because it does not require an indwelling percutaneous drain with the attendant risks of bile leak and sepsis. For similar reasons, magnetic resonance cholangiopancreatography (MRCP) may be preferred to PTC in patients in whom complete biliary transection precludes ERCP.
- Major biliary tract injuries are best managed in a tertiary referral center with particular expertise in this field.
- A cooperative multidisciplinary approach is required.
- The success of endoscopic therapy depends upon the type of injury.
- Surgery performed in the early postoperative phase in the absence of biliary dilatation and the presence of an acute local inflammatory response with or without ileus or sepsis is likely to ultimately fail. Endoscopic therapy is preferable at this stage. It will establish the diagnosis and may obviate the need for surgery. An attempt at endoscopic therapy does not preclude subsequent surgical intervention but the converse is not always true. Endoscopic stenting should be seen as a possible definitive therapy and at the very least a bridge to surgery.

Endoscopic therapy for strictures - Prophylactic broad spectrum antibiotic cover should be administered prior to ERCP. As for other benign biliary strictures, the technique is one of serial incremental biliary dilatation with successive placement of endoprostheses of increasing caliber side by side. The ultimate goal should be the placement of two 10 or 11.5 French gauge endoprostheses side by side across the stricture for a period of 9 to 12 months. (The persistance of a stricture after this time period warrants surgical intervention and further attempts at endoscopic management may result in secondary biliary cirrhosis). Sphincterotomy is usually performed due to the necessity for repeated stent exchanges and side by side stent placement.

Endoscopic therapy will not succeed in patients who have complete transection of the bile duct, as inevitably a guidewire cannot be passed across the lesion into the biliary tree above.

Outcome - Endoscopic therapy is associated with an excellent or good outcome in about three-quarters of patients. Delay in intervention beyond three months after the initial biliary injury may predispose to a less favorable response.

It is important to follow patients carefully following permanent biliary stent removal. Repeat cholangiography at 6 to 12 month intervals for the first two years is advisable as recurrent biliary stenosis may present insidiously. The results of endoscopic therapy for major biliary tract injury (excluding disconnection) for selected patients are at least comparable to those of surgery. The two techniques should be seen as complementary. In contrast to surgery, endoscopic management is relatively simple, reversible, and minimally invasive. Thus, endoscopic management should be an integral part of the therapeutic algorithm in the majority of patients with significant biliary tract injuries. For many of these patients, it may be the only therapeutic intervention necessary.

SURGERY
As has already been emphasised, complex hilar lesions or total transections, are usually not amenable to endoscopic treatment and early referral for surgical intervention is prudent.

The correct treatment of these injuries by surgeons experienced with this problem will ensure a successful long-term outcome of this reparative surgery in over 90% of these patients. On the other hand, attempted correction of this very serious problem by the initial operating surgeon who probably has limited or no experience with this situation has been associated with a very high failure rate (over 50% in most series) and repeated hospitalizations, operations, etc. have thus been necessary.

The principles of surgical management include careful preoperative preparation of the patient, control of sepsis and complete cholangiography. The level of injury to the duct is determined and for this purpose, the Bismuth or Hopital Paul Brousse classification is used. This is intended to help the surgeon choose the appropriate technique for the repair. Type I strictures, with a common duct stump longer than 2cm, can be repaired without opening the left duct and without lowering the hilar plate. Type II strictures, with a stump shorter than 2cm, require opening the left duct for a satisfactory anastomosis. Lowering the hilar plate is not always necessary but may improve the exposure. Type III lesions, in which only the ceiling of the biliary confluence is intact, require lowering the hilar plate and anastomosis on the left ductal system. There is no need to open the right duct if the communication between the ducts is wide. With type IV lesions the biliary confluence is interrupted and requires either reconstruction or two or more anastomoses. Type V lesions are strictures of the hepatic duct associated with a stricture on a separate right branch, and the branch must be included in the repair. Although this classification is intended for established strictures, it is commonly used to describe acute bile duct injuries. The surgeon must be aware, however, that the established stricture is generally one level higher than the level of the injury at the original operation.

It has to be emphasised again that surgical repair of bile duct injuries is best performed at a tertiary centre with the necessary expertise as the first attempt at repair offers the patient the best chance.

Iatrogenic bile duct injuries constitute a very serious problem and are almost certainly more common with the laparoscopic approach. Injury to the ductal structures is an acknowledged complication and does not necessarily represent medical negligence. What may constitute medical negligence in many of these cases is the inappropriate treatment of these injuries once they are recognized.

References:
1. Micheal Bourke - Endoscopic management of complications from laparoscopic
cholecystectomy - Sept 2000
2. Mark A. Talamini - Complications of Lap Cholecystectomy, Society of American Gl
Endoscopic Surgeons
3. Ahrendt SA - Surgical Therapy of iatrogenic lesions of biliary tract
4. Bismuth H, Majno PE - Biliary strictures: classification based on the principles of
surgical treatment
5. Gazzaniga CM - Surgical treatment of iatrogenic lesions of the proximal CBD