What Is Gastric Sleeve Surgery? Sleeve gastrectomy, sometimes also referred to as vertical sleeve gastrectomy, is a type of weight loss surgery. This procedure is performed laparoscopically, which means that it involves the insertion of small organs through incisions in the upper abdomen. This type of surgery removes about 80 percent of the stomach, leaving about 15 percent of the stomach – about the size and shape of a banana. What is gastric sleeve surgery? We have prepared a long article to give a detailed answer to the question.