Biliopancreatic Diversion and Duodenal Switch: Bariatric Surgery

Introduction
Biliopancreatic diversion (BPD) and duodenal switch (DS) are advanced bariatric procedures designed to promote significant weight loss through a combination of restrictive and malabsorptive mechanisms. These procedures are technically complex and are typically reserved for patients with higher BMIs or those who have not achieved success with other weight loss surgeries. While effective, they come with a higher risk of nutritional complications, requiring lifelong supplementation and close follow-up.

Background and Patient Selection
BPD was first introduced by Scopinaro and involves a distal gastrectomy and rearrangement of the small intestine to limit calorie absorption. The duodenal switch (DS) is a modification of BPD that preserves the pylorus and a portion of the duodenum, reducing the risk of marginal ulcers and dumping syndrome. Both procedures are malabsorptive in nature and are recommended for patients with severe obesity (BMI >50 kg/m²) or those who have failed other bariatric surgeries. Contraindications include preexisting nutrient deficiencies, inability to adhere to lifelong supplementation, and limited access to follow-up care.

Surgical Technique

Biliopancreatic Diversion (BPD)

1. Gastric Resection:
   • Perform a distal subtotal gastrectomy, leaving a 200-mL gastric pouch.
2. Intestinal Division:
   • Identify the terminal ileum and divide it 250 cm proximal to the ileocecal valve.
3. Anastomosis:
   • Anastomose the distal end of the divided ileum to the stomach, creating a 2–3 cm stoma.
   • Anastomose the proximal end of the ileum side-to-side to the terminal ileum, approximately 100 cm proximal to the ileocecal valve.
4. Cholecystectomy:
   • Perform a prophylactic cholecystectomy due to the high risk of gallstone formation from bile salt malabsorption.

Duodenal Switch (DS)

1. Gastric Sleeve Formation:
   • Perform a sleeve gastrectomy, leaving a narrow lesser curvature tube calibrated with a 32–40 French bougie.
2. Duodenal Division:
   • Divide the duodenum 2 cm distal to the pylorus.
3. Ileal Anastomosis:
   • Anastomose the distal 250 cm of ileum to the duodenum, often using a circular stapler for an end-to-end connection.
4. Biliopancreatic Limb Anastomosis:
   • Anastomose the biliopancreatic limb to the terminal ileum, similar to BPD.
5. Cholecystectomy:
   • Perform a prophylactic cholecystectomy.

Procedure-Specific Complications

1. Surgical Complications:
   • Leaks: Higher risk at the duodenoileal anastomosis in DS.
   • Bleeding: May occur at anastomotic sites.
   • Intestinal Obstruction: Reported in 1.2% of cases.
   • Marginal Ulcers: More common in BPD (2.8%) but reduced in DS due to pyloric preservation.
2. Nutritional Complications:
   • Protein Malnutrition: Occurs in 7% of patients, requiring parenteral nutrition in severe cases.
   • Iron Deficiency Anemia: Seen in less than 5% of patients.
   • Bone Demineralization: Reported in 53% of patients at 5 years postoperatively.
   • Vitamin Deficiencies: Night blindness (vitamin A deficiency) and alopecia (protein deficiency) may occur.
3. Gallstones:
   • High incidence due to bile salt malabsorption, necessitating prophylactic cholecystectomy.

Postoperative Management
Patients must adhere to lifelong nutritional supplementation, including vitamins, minerals, and protein. Regular follow-up is essential to monitor for deficiencies and complications. In cases of severe protein-calorie malnutrition, the common channel may need to be lengthened to improve nutrient absorption.

Mechanism of Action
Both BPD and DS combine restrictive and malabsorptive mechanisms:

• Restrictive Component: Reduction in stomach size limits food intake.
• Malabsorptive Component: Rearrangement of the small intestine reduces calorie and nutrient absorption.

Conclusion
Biliopancreatic diversion and duodenal switch are highly effective bariatric procedures for severe obesity but come with significant risks, particularly nutritional deficiencies. Careful patient selection, meticulous surgical technique, and lifelong follow-up are critical to achieving successful outcomes. These procedures are best performed by experienced surgeons in specialized centers.

Sleeve gastrectomy

: https://www.niddk.nih.gov/health-information/weight-management/bariatric-surgery