Bypass surgery refers to a class of surgery involving rerouting a tubular body part. Types include: * Vascular bypass surgery such as coronary artery bypass surgery, a heart operation * Cardiopulmonary bypass, a technique used in coronary artery bypass surgery * Weight loss or Bariatric surgery: * Vertical banded gastroplasty surgery or "stomach stapling", the upper part of the stomach is permanently stapled to create a smaller pouch * Adjustable gastric band or "lap band", a band creates a pocket in the stomach that can be adjusted with a port placed just under the skin * Roux-en-Y gastric bypass surgery, the small intestine is connected to the upper part of the stomach * Partial ileal bypass surgery, shortening the final portion of the small intestine * Popliteal bypass surgery,