Choice of surgical technique and anesthetic technique aims to reduce the risk of issues, shorten the time needed for recovery and minimise the surgical stress response. Prior to surgery, the individual is given a medical examination, receives certain pre-operative tests, and their bodily status is rated based on the ASA bodily status classification system. If these outcomes are passable, the person requiring surgery indicators a consent type and is given a surgical clearance. If the procedure is anticipated to end in significant blood loss, an autologous blood donation could also be made some weeks previous to surgery. If the surgery includes the digestive system, the individual requiring surgery may be instructed to perform a bowel prep by drinking a solution of polyethylene glycol the night earlier than the procedure. People preparing for surgery are additionally instructed to abstain from food or drink , to attenuate the effect of stomach contents on pre-operative medicines and scale back the chance of aspiration if the individual vomits during or after the procedure.