Bariatric Surgery & Postgastrectomy Syndromes
Pick the right operation, then catch the leak, the hernia, and the crash after sweets
Indications and choice of operation
Who qualifies. The 2022 ASMBS/IFSO guidelines recommend metabolic and bariatric surgery at BMI ≥35 regardless of comorbidity and advise considering it at BMI 30–34.9 with metabolic disease such as type 2 diabetes; thresholds are lower in Asian patients (surgery offered from about 27.5). Surgery usually follows an inadequate response to lifestyle and medical therapy. Contraindications include uncontrolled psychiatric illness, active substance use, and inability to commit to lifelong supplementation and follow-up.
Sleeve gastrectomy. About 75–80% of the stomach is removed along the greater curvature, including the ghrelin-rich fundus, leaving a narrow tube. It works by restriction and hormonal change, has no anastomosis or bypassed bowel, and is now the most common bariatric operation. It is irreversible but can be converted to a bypass.
Roux-en-Y gastric bypass (RYGB). A small gastric pouch of about 15–30 mL is joined to a Roux limb of jejunum, bypassing the distal stomach, duodenum, and proximal jejunum. It combines restriction, mild malabsorption, and incretin effects (more GLP-1 and PYY).
| Feature | Sleeve gastrectomy | Roux-en-Y gastric bypass |
|---|---|---|
| GERD | High-pressure tube can create or worsen reflux and Barrett esophagus | Operation of choice for severe GERD; diverts acid and bile from the esophagus |
| Weight loss and diabetes remission | Good | Greater |
| Micronutrient deficiencies | Fewer | More: iron, B12, folate, calcium, vitamin D |
| Signature complications | Proximal staple-line leak near the angle of His, stenosis at the incisura | Marginal ulcer, internal hernia, anastomotic stricture, dumping |
Early complications
Leak. An anastomotic or staple-line leak, usually in the first week, is the most feared early complication. Persistent tachycardia above 120/min may be the only sign, sometimes with fever, tachypnea, oliguria, or a sense of impending doom; peritoneal signs are unreliable in obesity. A stable patient gets a water-soluble upper GI contrast study or CT with oral contrast. Hemodynamic instability, or strong suspicion despite negative imaging, means return to the operating room.
Bleeding. Staple-line bleeding presents early as hematemesis or melena when intraluminal, or as a falling hemoglobin with tachycardia when intra-abdominal.
Venous thromboembolism. PE and leak are the leading causes of early death. Prevention combines early ambulation, compression devices, and weight-adjusted LMWH, extended after discharge in high-risk patients.
Unexplained tachycardia after bariatric surgery is a leak until proven otherwise; never attribute it to pain or anxiety without imaging or exploration.
Late complications
Internal hernia. After RYGB, bowel can herniate through mesenteric defects (Petersen space behind the Roux limb, the jejunojejunostomy defect), which widen as mesenteric fat melts with weight loss. Months to years later, patients have intermittent postprandial colicky periumbilical or left upper abdominal pain, often with near-normal labs, which can progress to closed-loop obstruction and strangulation. CT may show a mesenteric swirl but can be normal between episodes, so recurrent pain warrants diagnostic laparoscopy with reduction and closure of the defects.
Marginal ulcer. Ulcers form on the jejunal side of the gastrojejunostomy, promoted by smoking, NSAIDs, steroids, H. pylori, and ischemia. They cause epigastric pain, food intolerance, bleeding, or perforation with peritonitis, which needs operative repair. Confirm with EGD; treat with high-dose PPI (opened capsules), sucralfate, and elimination of smoking and NSAIDs, which bypass patients should avoid for life.
Anastomotic stricture. Typically 4–12 weeks after bypass, with progressive dysphagia and vomiting of solids, later liquids. EGD diagnoses it and treats it with balloon dilation, often repeated; after a sleeve, narrowing usually occurs at the incisura.
Gallstones. Rapid weight loss supersaturates bile with cholesterol and slows gallbladder emptying, so up to about a third of patients form stones within the first year. Ursodiol for about 6 months after surgery reduces stone formation. After RYGB, the duodenum cannot be reached with a standard endoscope, so ERCP requires a laparoscopy-assisted transgastric or enteroscopy-based approach.
Nutritional deficiencies
| Nutrient | Why it is lost | Clinical clue |
|---|---|---|
| Iron | Duodenum bypassed, less acid | Microcytic anemia, worst in menstruating women |
| Vitamin B12 | Little intrinsic factor and acid | Macrocytic anemia, neuropathy, loss of vibration and position sense |
| Folate | Reduced intake and absorption | Macrocytic anemia without neurologic signs |
| Calcium and vitamin D | Duodenum and proximal jejunum bypassed | Secondary hyperparathyroidism, bone loss |
| Thiamine | Stores last only weeks; vomiting | Wernicke encephalopathy, beriberi, neuropathy |
| Copper | Bypassed proximal bowel | Myeloneuropathy mimicking B12 deficiency |
Supplement choices. Calcium citrate is preferred because, unlike carbonate, it is absorbed without gastric acid. B12 can be given intramuscularly or in high oral doses.
Persistent vomiting after bariatric surgery, often from a stricture, can cause Wernicke encephalopathy (confusion, ophthalmoplegia or nystagmus, ataxia). Give IV thiamine immediately, before any dextrose, and treat the cause of vomiting.
Dumping and postgastrectomy syndromes
| Feature | Early dumping | Late dumping |
|---|---|---|
| Timing | 15–30 min after eating | 1–3 h after eating |
| Mechanism | Hyperosmolar chyme pulls fluid into the bowel; vasoactive peptides released | Rapid glucose absorption and an exaggerated incretin-driven insulin surge |
| Symptoms | Cramps, bloating, diarrhea, nausea, tachycardia, palpitations, flushing, lightheadedness | Reactive hypoglycemia: sweating, tremor, confusion, hunger |
| Specific drug | Octreotide if refractory | Acarbose, then octreotide |
Treating dumping. Diet comes first for both: small, frequent meals rich in protein and fiber, no simple sugars, and liquids separated from solids by about 30 minutes; lying down after meals eases early dumping. Acarbose slows carbohydrate absorption, octreotide is reserved for refractory cases, and surgical revision is rarely needed.
Afferent loop syndrome. After Billroth II gastrojejunostomy, a kinked, stenosed, or adherent afferent limb fills with bile and pancreatic juice. Postprandial RUQ pain and fullness are relieved by projectile vomiting of bile without food; complete obstruction causes pancreatitis, jaundice, or duodenal stump blowout. CT shows a dilated fluid-filled limb, and treatment is surgical, for example conversion to Roux-en-Y.
Bile reflux gastritis. After Billroth I or II reconstruction, bile refluxes into the gastric remnant, causing constant burning epigastric pain and vomiting of bile mixed with food that brings no relief. EGD shows friable, bile-stained, inflamed mucosa. PPIs, cholestyramine, and ursodiol help little; a long-limb Roux-en-Y gastrojejunostomy diverts bile and is curative. A blind afferent loop can also host bacterial overgrowth with B12 deficiency and steatorrhea, treated with antibiotics.