Question

A patient underwent cholecystectomy. A stone in the common bile duct (CBD) is detected 2 years after the surgery. What type of stone is it?

• A. Primary
• B. Secondary
• C. Tertiary
• D. Retained stone

Hint:

Recall the 2-year cut-off that distinguishes primary from secondary CBD stones after cholecystectomy.

Answer 1

The Correct Option is A

Step 1: Understand the classification of CBD stones (choledocholithiasis).
CBD stones are classified based on their origin and timing of detection relative to cholecystectomy:

Primary CBD stones: Stones that originate de novo within the common bile duct itself, after cholecystectomy. By definition, primary stones are detected more than 2 years after cholecystectomy. They are typically brown pigment stones (formed due to biliary stasis, infection with E. coli producing beta-glucuronidase, and bile duct stricture).

Secondary (Residual) CBD stones: Stones that have migrated from the gallbladder into the CBD, or stones remaining in the CBD after cholecystectomy. These appear within the first 2 years after surgery.

Retained stones: These are stones missed at the time of surgery (identified in the early postoperative period, typically within weeks).

Step 2: Apply the classification to the question.
The stone was detected 2 years after cholecystectomy -- exactly at (or beyond) the 2-year cut-off. By the standard definition, stones detected more than 2 years after cholecystectomy are classified as primary CBD stones (formed de novo in the duct).

Conclusion: The stone is a primary CBD stone.