Colonoscopy is a medical procedure in which a physician examines the large intestine. The exam is performed using an instrument called a colonoscope. The colonoscope consists of a long flexible tube with an imaging device, a light source, and certain other instruments. The instruments enable the physician to move the tube and perform other actions.
Before a colonoscopy, the patient takes medications to cleanse and empty the intestines. Patients are given a mild sedative to make them comfortable. A physician carefully places the colonoscope through the rectum and advances it into the colon. Through the colonoscope, the physician can examine the entire colon, up to the cecum (first part of the colon). The colonoscope can take photographs or a biopsy (tissue sample).
Doctors perform colonoscopies for a number of reasons. The most common reason for a colonoscopy is to check for cancer of the colon or rectum. Colon cancer often arises in polyps, small noncancerous growths in the intestine. These polyps can be located and safely removed during colonoscopy using special forceps or a wire snare device. Other reasons to perform a colonoscopy include determining the causes of diarrhea or bleeding from the intestine.
See also Colon cancer .
