What is the option for malabsorptive surgery?
Biliopancreatic diversion with and without a duodenal switch is a surgical option for malabsorption. A subtotal gastrectomy or sleeve gastrectomy is performed, leaving a gastric remnant of 250 to 500 mL. The small bowel is divided 200 to 300 cm proximal to the ileocecal valve, and the ileum is anastomosed to the stomach or first portion of the duodenum (duodenal switch). The jejunum is connected to the side of the ileum approximately 50 to 100 cm from the ileocecal valve—the “common channel.” This procedure results in malabsorption by creating a short common channel for digestion and absorption of food/calories. Chronic diarrhea is common if the patient is not very careful with diet. Similarly, a “distal” gastric bypass involves creating a short common channel, leading to considerable malabsorption. These are the most effective options for weight loss and resolution of comorbidities but carry the highest short-term and long-term risks. The biliopancreatic diversion has been gaining in popularity because of its excellent long-term weight loss results and is now being studied as a single anastomosis operation to decrease the morbidity and make it a more applicable option.
Combined restrictive/malabsorptive option.
Known as the “proximal” Roux-en-Y gastric bypass, the proximal stomach is stapled to create a small 15- to 30-mL proximal stomach pouch, which is completely separated from the excluded remnant stomach. This small reservoir restricts the amount of food that can be ingested at one time, forcing portion control similar to the purely restrictive surgical options. The proximal jejunum is then divided distal to the ligament of Treitz, and the distal end is anastomosed to the small stomach pouch (the Roux limb). The proximal end of the jejunum (the biliopancreatic limb) is then anastomosed to the side of the Roux limb (the “Y” connection) 75- to 150-cm distal to the gastrojejunostomy. The length of this Roux limb determines to a small degree the amount of calorie malabsorption; it is typically made longer for patients with high BMIs. There is malabsorption of vitamin and minerals from the bypass of the proximal jejunum. The effect of creating the Roux limb leads to dumping syndrome and forced aversion, and avoidance of simple sugars and fatty foods. This operation causes weight loss as a result of portion control (restriction), dumping syndrome, and, to a lesser degree, malabsorption of calories