Bariatric Surgery

Bariatric surgery refers to a group of invasive procedures used to surgically reduce the size of the stomach to produce early satiety, decrease food intake (restrictive type) and/or alter digestion, and artificially induce malabsorption of nutrients (malabsorptive type). The ultimate goal of bariatric surgery is drastic weight loss. Bariatric surgery is currently the only modality that provides significant long-term weight loss in morbidly obese individuals and cures or significantly improves obesity-related complications. The 2 modalities currently in wide use are the Roux-en-Y gastric bypass and sleeve gastrectomy.

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Surgical Anatomy


Bariatric surgery is a group of invasive procedures that can be used to either surgically reduce the size of the stomach or reroute the intestines with the ultimate goal of drastic weight loss by restricting food intake or altering the absorption of food.


It is important to review the anatomy of the stomach to more easily locate and recognize it within the abdominal cavity, as well as to promptly control bleeding during surgery.

Anatomical landmarks of the stomach:

  • Has 2 curvatures (lesser and greater)
  • Cardia: 
    • Entrance of the stomach
    • Originates from the z-line and creates the angle of His or angle of the cardiac orifice (angle between the fundus and abdominal esophagus)
    • A crucial landmark in construction of the gastric pouch 
  • Fundus: a dome-shaped region located at the highest point of the stomach
  • Body: 
    • The main section of the stomach
    • Extends from the fundus to the pylorus
    • Bordered by the lesser and greater curvatures
  • Pylorus: 
    • Connects to the duodenum
    • Contains the pyloric sphincter
    • Consists of a wide pyloric antrum and narrow pyloric canal
Stomach anatomy

Anatomy of the stomach

Image by BioDigital, edited by Lecturio
Stomach in situ

The stomach in situ

Image by BioDigital, edited by Lecturio

Arterial supply:

  • Left gastric artery: main supply to the gastric pouch in a gastric bypass
  • Right gastric artery
  • Right and left gastroepiploic (gastro-omental) arteries
  • Splenic artery
  • Short gastric arteries
  • Posterior gastric artery

Venous drainage:

  • Homonymous veins that accompany the arteries
  • Right and left gastric veins drain into the portal vein.
  • Left gastroepiploic vein drains into the splenic vein.
  • Right gastroepiploic vein drains into the superior mesenteric vein.


  • Parasympathetic innervation: anterior and posterior vagal trunk
  • Sympathetic innervation: greater splanchnic nerve and gastric branches from the celiac plexus
Blood supply and innervation of the stomach

Blood supply and innervation of the stomach

Image by BioDigital, edited by Lecturio

Indications and Contraindications

Eligibility criteria

Bariatric surgery is a type of surgical management indicated in patients with morbid obesity in whom lifestyle modifications (e.g., diet and exercise), psychotherapy, and pharmacotherapy have failed.

  • BMI > 40 kg/m2
  • BMI > 35 kg/m2 with complications of obesity (e.g., diabetes mellitus, hypertension, obstructive sleep apnea)
  • Previous failure of diet therapy
  • Psychiatric stability without alcohol use or the consumption of illicit drugs
  • Patients who are aware of the implications of surgery and the dietary changes that are required
  • Patients who are motivated
  • Underlying medical problems are not contraindications for surgery.



  • Patients > 65 years of age
  • Children and adolescents (surgery is delayed until they have reached maximal pubertal growth)
  • Underlying medical conditions (e.g., cardiac or respiratory diseases)
  • Pre-existing GERD for gastric sleeve (but not for gastric bypass)


  • Inability to ambulate
  • Prader-Willi syndrome


Preoperative preparation

  • Prior fasting/bowel rest (nil per os, nothing by mouth) for 8 hours
  • Explanation of the procedure to the patient and obtaining informed consent
  • Laboratory workup:
    • CBC: platelet count > 50,000
    • PTT and PT within acceptable ranges
    • Renal function: serum creatinine and BUN within acceptable ranges
  • Anticoagulants are withheld before the procedure.
  • Deep vein thrombosis (DVT) prophylaxis: 
    • Enoxaparin
    • Compression stockings
  • Antibiotic prophylaxis: 1st-generation cephalosporins (cefazolin) 
    • Dose must be appropriate to the patient’s weight.
    • Prophylaxis is continued for 24 hours after the procedure.
  • Continuous monitoring:
    • HR
    • BP
    • Oxygen saturation 
    • ECG
  • Anesthesia: The procedure is usually performed under general anesthesia.

Types and steps of the procedures

Roux-en-Y gastric-bypass technique:

Gastric bypass is both restrictive (reduces the size of the stomach) and malabsorptive (reroutes the intestines to alter food absorption). A laparoscopic approach is generally preferred because of shorter recovery and hospital stay.

  1. The hepatogastric ligament is dissected perigastrically to avoid injury to the nerve of Latarjet. 
  2. The 20–30-mL gastric pouch is fashioned based on the lesser curvature of the stomach, providing the restrictive component.
  3. The Roux limb is brought up to the gastric pouch by any of the following paths:
    • Antecolic/antegastric
    • Retrocolic/retrogastric (shortest path)
    • Retrocolic/antegastric
  4. The Roux limb is anastomosed with the gastric pouch using non-absorbable sutures or staples.
  5. To prevent herniation, the following defects are closed:
    • Peterson’s defect (space between the limbs of the small intestine, the transverse mesocolon, and the retroperitoneum)
    • Intermesenteric defect (space within the mesenteric pouch)
    • Defect in the transverse mesocolon
Roux-en-y gastric bypass

Roux-en-Y gastric bypass

Image by Lecturio.

Gastric sleeve technique:

The goal is to create a smaller, tube-shaped stomach along the lesser curvature with a volume of approximately 60–100 mL. This procedure is most commonly performed laparoscopically.

  1. The short gastric vessels along the greater curvature are transected.
  2. The phrenoesophageal ligament and gastroesophageal fat pad are divided to expose the left diaphragm. 
  3. The greater curvature of the stomach is released and an elastic bougie (a long plastic tube used to calibrate the size of the sleeve) is inserted. 
  4. A linear cutting stapler is moved parallel to the lesser curve of the stomach, starting at the antrum and progressing towards the fundus, while being careful to not impinge on the incisura.
  5. At the fundus, the linear stapler is moved medially to the angle of His, and the greater curvature is completely resected to create the gastric sleeve.
  6. The remnant stomach is then removed.
Gastric sleeve

Gastric sleeve

Image by Lecturio.

Post-operative care

  • Observation in the recovery room for 6 hours and later in the wards
  • Same-day discharge is possible.
  • Special diet plan with small frequent meals to avoid vomiting, food intolerance, and dumping syndrome
  • Careful follow-up of patients by a multidisciplinary team is necessary:
    • Monitoring of weight loss
    • Vigilance for malnutrition and vitamin deficiencies
  • Plastic surgery: Aesthetic procedures may be indicated to remove excess skin from the abdomen, thighs, and arms after drastic weight loss.
  • Prognosis:
    • Greatest extent of weight loss occurs during the 1st postoperative year.
    • Gastric bypass provides slightly better-maintained weight loss at 5 years than the gastric sleeve.
    • Best means to cure obesity-related complications: improves or cures type 2 diabetes, hypertension, and hyperlipidemia
    • Significant number of patients develop gallstones secondary to rapid weight loss:
      • If symptomatic, cholecystectomy is indicated
      • Some surgeons advocate prophylactic cholecystectomy at the time of bariatric surgery.


Bariatric surgery, like any invasive procedure, has inherent risks and complications.

Roux-en-Y gastric bypass

  • Anastomotic leak:
    • May lead to intra-abdominal abscess, peritonitis, and sepsis
    • Potentially life-threatening complication
  • Bleeding along the suture or staple lines
  • Anastomotic stenosis (results in obstruction)
  • Marginal ulcers: form at the GI anastomosis usually on the intestinal side, as a result of unopposed exposure to gastric acid
  • Gastro-gastric fistula: fistula formation between the gastric pouch and gastric remnant
  • Nutritional deficiencies:
    • Result from exclusion of the large portion of the stomach and inadequate absorption due to intestinal bypass
    • Common deficiencies: vitamin B12, folate, iron, zinc, copper, calcium, vitamin D
  • Dumping syndrome:
    • Caused by rapid movement of large amounts of food from a small stomach into the intestine
    • Usually associated with foods rich in simple sugars and starches
    • Presents as bloating, abdominal discomfort, and diarrhea
    • Can also be associated with tachycardia and hypotension due to massive fluid influx into the intestinal lumen

Gastric sleeve

  • Gastroesophageal reflux: due to increased pressure within a narrow, tubular stomach
  • Leakage along the staple line
  • Bleeding from the staple line


  1. Hardwick, R. (2018). The esophagus, stomach, and duodenum. In Garden, O. James.
  2. Lyo, V., Husain, F.A. (2021). Roux-en-Y gastric bypass and sleeve gastrectomy. In Delaney, Conor P. et al. (Ed.), Netter’s Surgical Anatomy and Approaches. 
  3. Standring, S. (2021). Abdominal oesophagus and stomach. In Standring, Susan (Ed.), Gray’s Anatomy (pp. 1160–1172.e1).

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