Question

All of the following are primary restrictive operations for morbid obesity, except:

• A. Vertical banded gastroplasty
• B. Duodenal switch operation
• C. Roux-en-Y gastric bypass
• D. Laparoscopic adjustable gastric banding

Hint:

Which listed operation works mainly by bypassing small bowel rather than shrinking the stomach?

Answer 1

The Correct Option is B

Step 1: Bariatric operations are grouped as restrictive (reduce stomach volume so the patient eats less), malabsorptive (bypass small bowel so less is absorbed), or combined.
Step 2: Vertical banded gastroplasty (option A) creates a small upper gastric pouch with a banded outlet, so it is purely restrictive.
Step 3: Laparoscopic adjustable gastric banding (option D) places an inflatable band around the upper stomach to limit intake, so it is purely restrictive.
Step 4: The duodenal switch (option B) combines a sleeve gastrectomy with a biliopancreatic diversion that bypasses most of the small intestine. It is predominantly a malabsorptive (combined) procedure, not a primary restrictive one. This is the exception.
Step 5: Roux-en-Y gastric bypass (option C) is classically taught as a combined procedure, but it is dominated by gastric restriction from the small pouch, so among the given choices it is treated as the restrictive component and the printed key marks the duodenal switch as the odd one out.
Answer: B. Duodenal switch operation.