section_path: Description of surgical procedure/Preoperative care
section_name: Preoperative care
paragraph_text: Preoperative care
  
  Prior to surgery, the person is given a medical examination, receives certain pre-operative tests, and their physical status is rated according to the ASA physical status classification system. If these results are satisfactory, the person requiring surgery signs a consent form and is given a surgical clearance. If the procedure is expected to result in significant blood loss, an autologous blood donation may be made some weeks prior to surgery. If the surgery involves the digestive system, the person requiring surgery may be instructed to perform a bowel prep by drinking a solution of polyethylene glycol the night before the procedure. People preparing for surgery are also instructed to abstain from food or drink (an NPO order after midnight on the night before the procedure), to minimize the effect of stomach contents on pre-operative medications and reduce the risk of aspiration if the person vomits during or after the procedure.
  
  Some medical systems have a practice of routinely performing chest x-rays before surgery. The premise behind this practice is that the physician might discover some unknown medical condition which would complicate the surgery, and that upon discovering this with the chest x-ray, the physician would adapt the surgery practice accordingly. However, medical specialty professional organizations recommend against routine pre-operative chest x-rays for people who have an unremarkable medical history and presented with a physical exam which did not indicate a chest x-ray. Routine x-ray examination is more likely to result in problems like misdiagnosis, overtreatment, or other negative outcomes than it is to result in a benefit to the person. Likewise, other tests including complete blood count, prothrombin time, partial thromboplastin time, basic metabolic panel, and urinalysis should not be done unless the results of these tests can help evaluate surgical risk.