What is the definition or description of: proctosigmoidoscopy?

Rectal endoscopy: Proctosigmoidoscopy is an examination of the rectum and sigmoid colon (just above the rectum) using a narrow, rigid scope with a built-in light. A small amount of air is usually introduced to distend the bowel, allowing for a better view. Generally, a limited prep is helpful, but not always necessary. Discomfort should be minimal.