Bismuth Classification of Benign Biliary Stricture
The Bismuth-Corlette classification system categorizes benign biliary strictures (and perihilar cholangiocarcinoma) into five types (I-V) based on the anatomical location and extent of biliary duct involvement at the hepatic hilum. 1
Classification System
The Bismuth classification divides strictures according to their extension along the biliary ducts as follows 1:
Type I
- Stricture involves the common hepatic duct more than 2 cm distal to the hepatic confluence 1
- The hepatic duct confluence remains intact and uninvolved 1
Type II
- Stricture extends to the hepatic confluence but does not involve the right or left hepatic ducts 1
- The confluence itself is involved but the bifurcation remains patent 1
Type III
- Stricture involves the confluence and extends into either the right hepatic duct (Type IIIa) or left hepatic duct (Type IIIb) 1
- The contralateral hepatic duct remains uninvolved 2
Type IV
- Stricture involves the confluence and extends into both right and left hepatic ducts 1
- Complete involvement of the biliary bifurcation 1
Type V
- Stricture involves an aberrant right sectoral hepatic duct in addition to the common hepatic duct 1
- This type accounts for anatomical variations 3
Clinical Significance and Surgical Planning
The Bismuth classification directly guides surgical approach and predicts operative complexity 1:
Types I and II: Managed with en bloc resection of extrahepatic bile ducts, gallbladder, regional lymphadenectomy, and Roux-en-Y hepaticojejunostomy 1
Type III: Requires the above procedures plus ipsilateral hepatectomy (right or left depending on which duct is involved) 1
Type IV: Generally not resectable, though extended hepatectomy may be feasible depending on biliary anatomy 1
Important Caveats and Proposed Modifications
A critical limitation exists: The original Bismuth classification does not account for isolated hepatic duct strictures (first- or second-order ducts) without involvement of the common hepatic duct or hilar confluence 4. A proposed Type VI has been suggested for these cases, which represent approximately 2% of post-cholecystectomy strictures 4.
Type III strictures require subclassification based on surgical complexity 2:
- Type IIIA: Healthy confluence with only ductal extension
- Type IIIB: Scarred floor of confluence with maintained ductal continuity
Type IIIB strictures behave similarly to Type IV in terms of operative difficulty, blood loss (635 mL vs 317 mL, P=0.004), transfusion requirements (2.2 vs 0.8 units, P=0.0007), and operative duration (5.1 vs 3.8 hours, P=0.002) 2.
Diagnostic Challenges
Differentiating benign from malignant strictures remains problematic despite advanced diagnostics 5. Approximately 3-10% of presumed malignant strictures prove benign on final pathology, with IgG4-related sclerosing cholangitis being an important mimicker 1, 5. The multidisciplinary team must maintain awareness of autoimmune cholangitis and stone disease as alternative diagnoses 1.
Treatment Approach by Type
Endoscopic therapy with balloon dilation and serial stenting is first-line for most benign biliary strictures 3. However, outcomes vary significantly by etiology and Bismuth type 3: