 It is considered somewhat of a safe surgical procedure, with a mortality rate of 0.05%.Sleeve gastrectomy, or gastric sleeve, is a surgical weight-loss procedure in which the stomach is reduced to about 15% of its original size, by the surgical removal of a large portion of the stomach, following the major curve.The open edges are then attached together (typically with surgical staples, sutures, or both) to leave the stomach shaped more like a tube, or a sleeve, with a banana shape.