**2.2 Laparoscopic sleeve gastrectomy (LSG)**

The most common bariatric surgery, which is performed is sleeve gastrectomy (SG) [17]. Some advantages include intact and normal intestinal absorption, preservation of pylorus preventing dumping syndrome, technical efficiency, and the first appropriate step for extremely obese patients [18]. Additional benefits, such as maintaining gastrointestinal integrity and preventing malabsorption [19]. The extreme objective of the method is to evacuate between 60 and 70% of the stomach, counting the fundus, leaving a long, thin banana-shaped stomach [17, 18]. Narrowing of the gastric leads to significant limitations of stomach capacity also in other metabolic modifications. Ghrelin is one of the hormones that increments and stimulates the patient's appetite. It is produced by cells found within the fundus. Resection of the fundus significantly diminished the basal level of ghrelin, diminishing appetite in patients who experienced LSG [18]. PYY increased postoperatively and leptin, insulin and ghrelin decreased. Probably due to improved beta-cell function and improved insulin sensitivity, insulin levels decreased following LSG. Also, decreased postoperative leptin levels may be related to decreased leptin resistance or improved leptin sensitivity [20]. LSG has illustrated its effectiveness in accomplishing weight loss and determination of obesityrelated comorbidities; the concept of SG is simple, but performing incorrectly some components can cause serious complications [18]. Bleeding, staple line leak, stenosis, venous thromboembolism, intra-abdominal abscess, gastroesophageal reflux, and strictures are complications associated with LSG [17]. Staple line leakage and bleeding are the major complications in the early postoperative period. The most common complication, which occurs in about 1.1–8.7% of cases, is staple line bleeding. The most life-threatening and dangerous complication is leakage of staple line with 0.5%-2.7 incidence ranging [21]. The potential causes of leakage are a technical failure, a stapler's mechanical failure, functionality and the shape of the sleeve, high intraluminal pressure, incisura angularis obstruction, or poor wound healing [19]. Primary subphrenic abscess and secondary rupture of the diaphragm, which can rarely be caused by gastric leakage, eventually will lead to gastrobronchial fistula. Gastrobronchial fistula is a chronic gastric leakage late complication located above the staple line [22]. Compared to laparoscopic adjustable gastric banding (LAGB), a very popular method over a decade before, sleeve gastrectomy is a simple yet powerful metabolic operation that changes the eating behavior, gut functions, and glycemic control by activating hormonal pathways, and the procedure needs no foreign implant. And compared to RYGB, it is technically easier and does not require intestinal anastomosis. The LSG is limited to the stomach and prevents the presence of an internal hernia in postoperative follow-up [23].
