Colonoscopy Procedure Overview

(Lower Endoscopy)

Procedure Overview

What is a colonoscopy?

Colonoscopy is a diagnostic procedure that allows the physician to examine the entire length of the large intestine. Colonoscopy can assist in identifying problems with the colon, such as early signs of cancer, inflamed tissue, ulcers, and bleeding. Colonoscopy is also used to screen for colorectal cancer, the second leading cause of cancer-related deaths in the US and the fourth most common cancer in men and women.

An endoscope - a long, flexible, lighted tube (also called a colonoscope), is inserted through the rectum into the colon. In addition to allowing visualization of the internal colon, the colonoscope enables the physician to irrigate, suction, inject air, and access the bowel with surgical instruments. During a colonoscopy, the physician may remove tissue and/or polyps for further examination and possibly treat any problems that are discovered.

Other related procedures that may be used to assess problems of the colon include abdominal x-ray, computed tomography (CT scan) of the abdomen, abdominal ultrasound, barium enema, and sigmoidoscopy. Please see these procedures for additional information.

Anatomy of the colon:

The large intestine, or colon, has four sections:

  • ascending colon - extends upward on the right side of the abdomen

  • transverse colon - extends from the ascending colon across the body to the left side

  • descending colon - extends from the transverse colon downward on the left side

  • sigmoid colon - named because of its S-shape; extends from the descending colon to the rectum

The rectum joins the anus, or the opening where waste matter passes out of the body.

Screening guidelines for colorectal cancer:

Colorectal cancer screening guidelines for early detection from the American Cancer Society recommend that beginning at age 50, both men and women should follow one of the examination schedules below:

  • annual fecal occult blood test (FOBT) or fecal immunochemical test (FIT) and flexible sigmoidoscopy (FSIG) every five years

  • FOBT or FIT every year

  • FSIG every five years

  • double-contrast barium enema every five years

  • colonoscopy every 10 years

Persons with any of the following colorectal cancer risk factors should begin screening procedures at an earlier age and be screened more often:

  • strong family history of colorectal cancer or adenomatous polyps in a first-degree relative, in a parent or sibling before the age of 60 or in two first-degree relatives of any age

  • family with hereditary colorectal cancer syndromes, such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC)

  • personal history of colorectal cancer or adenomatous polyps

  • personal history of chronic inflammatory bowel disease

Reasons for the Procedure

A colonoscopy may be used to examine colon polyps, tumors, ulceration, inflammation, diverticula (pouches), strictures (narrowing), and foreign objects within the colon. It may also be used to determine the cause of unexplained chronic diarrhea or gastrointestinal bleeding or to evaluate the colon after cancer treatment.

Colonoscopy may be indicated when the results of a barium enema and/or sigmoidoscopy warrant further examination of the colon.

There may be other reasons for your physician to recommend a colonoscopy.

Risks of the Procedure

As with any invasive procedure, complications may occur. Complications related to colonoscopy include, but are not limited to, the following:

  • persistent bleeding after biopsy or polyp removal

  • peritonitis (inflammation of the lining of the abdominal cavity)

  • perforation of the intestinal wall (rare)

  • nausea, vomiting, bloating, or rectal irritation caused by the bowel cleanse prep and/or procedure

  • adverse reaction to the sedative or pain medication



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