Bypass SASI - Intestinal Bipartition Surgery
How Does SASI Bypass Work
The Single Anastomosis Sleeve Ileal (SASI) Bypass is a hybrid metabolic surgery that combines restriction and malabsorption to promote weight loss and improve metabolic health. Below is a detailed breakdown of how the procedure works, its physiological effects, and why it’s effective for obesity and type 2 diabetes.
1. The Two Key Components of SASI Bypass
A. Sleeve Gastrectomy (Restrictive Component)
Stomach Reduction: About 70-80% of the stomach is surgically removed, leaving a banana-shaped tube.
Food Intake Restriction: The smaller stomach limits how much food can be eaten at once, promoting early satiety.
Hormonal Changes: The removal of the stomach’s fundus (where ghrelin, the hunger hormone, is produced) leads to reduced appetite.
B. Single Anastomosis Ileal Bypass (Malabsorptive Component)
Intestinal Rerouting: The small intestine is divided 250-300 cm from the ileocecal valve (near the end of the small intestine).
Single Connection (Anastomosis): The sleeve stomach is directly connected to the ileum, bypassing most of the duodenum and jejunum (where most nutrient absorption occurs).
Reduced Calorie Absorption: Since food travels a shorter path, fewer calories and fats are absorbed.
Hormonal Benefits: The rerouting enhances GLP-1 and PYY secretion, improving insulin sensitivity and metabolic function.
Step-by-Step Surgical Procedure
Step 1: Laparoscopic Approach (Minimally Invasive)
The surgery is performed through small incisions using a laparoscope.
General anesthesia is administered.
Step 2: Creation of the Sleeve Stomach
The surgeon removes the outer curvature of the stomach, leaving a narrow, tubular pouch.
The remaining stomach holds ~100-150 mL (compared to 1,000+ mL before).
Step 3: Division of the Small Intestine
The small intestine is measured ~250-300 cm from the ileocecal valve (varies by patient).
The intestine is cut at this point, separating it into two segments:
Proximal (upper) segment (connected to the stomach)
Distal (lower) segment (carries digestive juices)
Step 4: Single Anastomosis (Connection)
The sleeve stomach is connected directly to the ileum (bypassing the duodenum and jejunum).
The distal segment (carrying bile and pancreatic enzymes) is reattached further down to aid digestion.
Step 5: Closure & Recovery
The incisions are closed, and the patient is monitored in recovery.
Most patients stay in the hospital for 2-3 days.
How SASI Bypass Promotes Weight Loss & Metabolic Improvement
Mechanism 1: Restricted Food Intake
The smaller stomach limits meal sizes, leading to reduced calorie consumption.
Patients feel full faster and stay satisfied longer.
Mechanism 2: Reduced Nutrient Absorption
Since food bypasses ~60-70% of the small intestine, fewer calories (especially fats) are absorbed.
This creates a controlled malabsorption effect, enhancing weight loss.
Mechanism 3: Hormonal Changes (Key for Diabetes Control)
Increased GLP-1: The ileal stimulation boosts glucagon-like peptide-1 (GLP-1), which:
Improves insulin sensitivity
Reduces blood sugar levels
Suppresses appetite
Reduced Ghrelin: With most of the stomach removed, hunger signals decrease.
Mechanism 4: Faster Gut Hormone Signaling
Food reaching the ileum sooner triggers satiety hormones (PYY) faster, reducing cravings.
