Special Surgery 34. Bariatric Surgery

I. Definition, Indications and Patient Selection

Definition

• Bariatric/metabolic surgery: surgical treatment of obesity
• Aim: significant sustained weight loss + improvement of obesity-related comorbidities
• Mechanisms: restriction of food intake ± malabsorption ± hormonal/metabolic effects

Indications

• BMI >=40 kg/m2 → regardless of comorbidities
• BMI >=35 kg/m2 + serious obesity-related comorbidity:

• Type 2 diabetes mellitus
• Hypertension
• Obstructive sleep apnea
• Dyslipidemia
• NAFLD/NASH

• BMI >=30 kg/m2 → may be considered in selected cases, e.g. uncontrolled diabetes, especially in Asian patients

Additional Requirements

• Failure of conservative treatment: diet, exercise, behavioral therapy, medication
• Multidisciplinary assessment: surgeon + dietitian + anesthesia/internal medicine + psychological assessment
• Patient understands lifestyle changes, risks and lifelong follow-up
• No major contraindication:

• Uncontrolled psychiatric illness
• Active alcohol/drug abuse
• Unsafe eating disorder behavior
• Inability to comply with supplements/follow-up
• Prohibitive surgical/anesthetic risk

II. Types of Bariatric Surgery

1. Restrictive Procedure: Sleeve Gastrectomy

• Sleeve gastrectomy (SG): most commonly performed worldwide
• About 70-80% of stomach removed → narrow gastric sleeve remains
• Mechanism: reduced volume → early satiety
• Hormonal effect: decreased ghrelin → less hunger
• Pros: technically simpler than bypass, no intestinal anastomosis, good weight loss
• Cons: irreversible, staple-line leak/bleeding risk, GERD may worsen or appear

2. Restrictive + Malabsorptive Procedures

• Roux-en-Y gastric bypass (RYGB):

• Small gastric pouch connected directly to jejunum
• Bypasses most of stomach + duodenum
• Mechanism: restricted intake + reduced absorption + metabolic hormone effects
• Pros: excellent weight loss, strong type 2 diabetes improvement, lower GERD risk than sleeve
• Cons: more complex, internal hernia, dumping syndrome, marginal ulcer, nutritional deficiencies

• Biliopancreatic diversion with duodenal switch (BPD/DS):

• Sleeve gastrectomy + significant small bowel bypass
• Strongest weight-loss and metabolic effect
• Used selectively for severe obesity and severe type 2 diabetes
• Cons: highest nutritional/protein deficiency risk, less common

III. Outcomes and Complications

Outcomes / Benefits

• Sustained weight loss: about 25-35% of initial body weight
• Improved glycemic control or remission of type 2 diabetes
• Improved hypertension, lipid profile and obstructive sleep apnea
• Improved NAFLD/NASH in many patients
• Improved quality of life and reduced long-term mortality in appropriate patients

Short-Term Complications

• Bleeding
• Wound/intra-abdominal infection
• Staple-line or anastomotic leak → tachycardia, fever, abdominal pain, sepsis
• DVT/PE → prevention with mobilization + compression + pharmacologic prophylaxis
• Early obstruction or anastomotic edema

Long-Term Complications

• Nutritional deficiencies: iron, vitamin B12, folate, calcium, vitamin D
• BPD/DS: highest risk of protein and fat-soluble vitamin deficiency
• Dumping syndrome: especially after RYGB
• Marginal ulcer: especially after RYGB; risk increased by smoking/NSAIDs
• Internal hernia: post-RYGB; intermittent abdominal pain/vomiting → urgent evaluation
• GERD: more common or worsened after sleeve gastrectomy
• Gallstones and weight regain

IV. Follow-Up and Exam Summary

Lifelong Follow-Up

• Lifelong multidisciplinary follow-up is mandatory:

• Surgical/bariatric team
• Dietitian/nutrition specialist
• Psychological support if needed
• Primary care/endocrinology for comorbidity medication adjustment

• Monitor weight loss, weight regain, diet tolerance and mental health
• Delay pregnancy during rapid weight-loss phase, usually 12-18 months

Nutrition and Supplements

• Diet progression: liquids → pureed/soft → solid high-protein diet
• Small meals, slow eating, avoid high-sugar foods especially after bypass
• Long-term supplements:

• B12
• Iron
• Folate
• Calcium + vitamin D
• Bariatric multivitamin; extra fat-soluble vitamins after BPD/DS

• Regular labs: CBC, iron/ferritin, B12, folate, calcium/vitamin D, glucose/HbA1c, lipids

Exam Summary

• Sleeve gastrectomy: common, restrictive + hormonal, may worsen GERD
• Roux-en-Y gastric bypass: restrictive + malabsorptive/metabolic, good for diabetes and reflux, risk of dumping/internal hernia/deficiencies
• BPD/DS: strongest metabolic effect, highest nutritional risk
• Early danger signs after surgery: tachycardia, fever, severe abdominal pain, vomiting, GI bleeding, dyspnea/chest pain
• Bariatric surgery = operation + lifelong supplementation and follow-up