The reality that obesity and diabetes pose a significant health threat globally has paved the way for innovations in obesity and metabolic surgery procedures. The discovery of neuroendocrine hormones produced in the stomach and intestines (GLP-1, PYY, Ghrelin) and understanding their effects on satiety, fullness, and appetite mechanisms have made methods involving the intestines more popular in surgical strategies. New methods aim to utilize neuroendocrine effects beyond creating mechanical restriction and malabsorption issues.

In the Loop Bipartition, also known as SASI-Bypass surgery, the patient undergoes a sleeve gastrectomy, followed by connecting the intestine to the stomach 250cm from the end of the small intestine. Due to the normal use of the stomach’s anatomical exit, vitamin deficiencies are less common in patients.

What is Loop Bipartition?

Similar to the oldest metabolic surgery method, the duodenal switch, performed for about 40 years, transit bipartition surgery does not close the duodenum, thus reducing absorption-vitamin issues. The long-term results of transit bipartition, which allows earlier encounter of the middle and end parts of the small intestine with food, leading to immediate satiety, are similar to those of the duodenal switch. This method maximizes neuroendocrine effects while minimizing malabsorption issues. Direct bypassing of a part of the stomach or intestine, compared to other surgery types, prevents vitamin deficiencies if a glucose-free diet is maintained.

Loop Bipartition

The Role of the Satiety Hormone GLP-1 and the Small Intestine

There are two types of bipartition surgery: 1. Transit bipartition and 2. Loop bipartition. In transit bipartition, reducing the stomach and reconnecting the small intestine aids in weight loss and diabetes control. In Loop bipartition, a second connection in the small intestine is added to the classic sleeve gastrectomy. This connection is placed 250 cm back from the beginning of the large intestine. Surgeons attach the movable intestine to the bottom of the remaining stomach. The connection diameter is between 2.5-3 cm and can be adjusted depending on weight loss progress. Loop bipartition is especially suitable for patients with fasting blood glucose over 126 or those resistant to obesity treatment.

This method, preferred especially for those dependent on carbohydrates, reduces appetite and balances hormones. Ghrelin, a hormone produced in the stomach that increases appetite, is not secreted with this method, quickly creating a sensation of fullness. Conversely, the satiety hormone GLP-1 is produced in the small intestine, sending signals to the brain to induce fullness. This method does not disrupt absorption but activates hormones. However, carbohydrate intake can speed up intestinal movements, leading to diarrhea. The brain draws water to dispose of the unabsorbed sugar, causing diarrhea. To prevent this, glucose should not be consumed. Additionally, the PYY hormone secreted from the small intestine induces aversion to animal fats. Consequently, patients may experience pregnancy-like symptoms.

Since the main exit of the stomach is not altered in this bypass type, the anatomy of the duodenum and stomach remains intact. This condition allows the application of ERCP, the gold standard for visualizing and treating bile ducts. Reverting this surgical method to its original state is much simpler compared to other bypass types.