Roux-en-Y

**Anatomy/Technique** - The jejunum is divided about 30-50 cm distal to the ligament of Treitz. - The distal cut end (Roux limb, or alimentary limb) is brought up and anastomosed to the target organ. In RYGB, the target is a small proximal gastric pouch (~15-30 mL). - The proximal cut end (biliopancreatic limb) carries bile and pancreatic enzymes from the excluded stomach remnant and duodenum. It is anastomosed to the Roux limb farther downstream (jejunojejunostomy), forming the "Y." - Food bypasses most of the stomach, the duodenum, and the proximal jejunum. Digestive secretions mix with food only at the common channel.

**Uses** - **Bariatric surgery (RYGB):** Weight loss comes from restriction (small pouch) and altered gut hormones (↑GLP-1, ↑PYY, ↓ghrelin), which increase satiety. Some malabsorption contributes. It often improves or resolves type 2 diabetes, often before significant weight loss occurs. - **Biliary reconstruction:** Hepaticojejunostomy or choledochojejunostomy after bile duct injury, choledochal cyst excision, or biliary strictures. It is also used in the Whipple procedure (pancreaticoduodenectomy). - **Esophagojejunostomy:** Used after total gastrectomy. - **Distal gastrectomy reconstruction:** Used to prevent bile reflux gastritis, because the long Roux limb diverts bile away from the gastric remnant.

**Complications (high-yield)** - **Dumping syndrome:** Rapid emptying of hyperosmolar chyme into the small bowel. - *Early (10-30 min):* Fluid shifts into the lumen cause abdominal pain, diarrhea, and vasomotor symptoms (flushing, tachycardia, hypotension). - *Late (1-3 h):* Rapid carbohydrate absorption causes an insulin surge and reactive hypoglycemia. - *Management:* Small frequent low-carbohydrate meals; acarbose or octreotide if refractory. - **Nutritional deficiencies:** - *Iron:* Duodenum bypassed; causes microcytic anemia. - *Vitamin B12:* Loss of intrinsic factor and acid; causes megaloblastic anemia and neuropathy. - *Calcium and vitamin D:* Duodenum and proximal jejunum bypassed; risk of osteoporosis and secondary hyperparathyroidism. - *Folate, thiamine, and copper:* Thiamine deficiency can cause Wernicke encephalopathy after vomiting. - Lifelong supplementation is required. - **Marginal ulcer:** Occurs at the gastrojejunal anastomosis. Risk factors are smoking, NSAIDs, and H. pylori. Treat with PPI and sucralfate. - **Anastomotic leak:** Early postoperative tachycardia, fever, and abdominal pain; this is an emergency. - **Internal hernia:** Through mesenteric defects (Petersen's space), causing small bowel obstruction. It is a classic late complication, especially after rapid weight loss. - **Anastomotic stricture:** Presents with dysphagia and vomiting. - **Gallstones:** Rapid weight loss increases risk. Ursodiol prophylaxis or concomitant cholecystectomy may be considered. - **Afferent (biliopancreatic) limb obstruction:** Causes pain and elevated amylase/lipase or LFTs. - **Roux stasis syndrome:** Delayed gastric emptying with nausea, vomiting, and early satiety after Roux reconstruction. - **Limited endoscopic access:** The excluded stomach and duodenum are hard to reach with standard EGD. Because of this, ERCP is difficult after RYGB. Options include laparoscopy-assisted ERCP, balloon enteroscopy-assisted ERCP, or EUS-directed transgastric ERCP (EDGE). - **Gastric cancer screening:** The excluded stomach is difficult to evaluate.

**Comparison with other bariatric procedures** - *Sleeve gastrectomy:* Restrictive only. It carries a higher GERD risk and has no malabsorption. - *Adjustable gastric band:* Restrictive only. Rarely used now. - *Biliopancreatic diversion with duodenal switch:* Most malabsorptive, with the highest risk of deficiencies and steatorrhea. - *RYGB:* Often preferred for patients with obesity plus GERD or diabetes.

**Eponym:** Named for César Roux, a Swiss surgeon (1897). The Roux-en-Y gastric bypass was later developed for weight loss by Mason and Ito (1960s) and refined by others.

**Boards pearls** - Obese patient post-RYGB with anemia and neuropathy: check B12 (plus iron and copper). - Post-RYGB patient with sweating, palpitations, and diarrhea after meals: dumping syndrome. - Post-RYGB patient with colicky pain and vomiting, with no hernia on exam: suspect internal hernia (CT with swirl sign). - Post-RYGB patient with epigastric pain, hematemesis, or perforation while on NSAIDs or smoking: marginal ulcer.