A lower GI endoscopy, also called colonoscopy or signmoidoscopy, allows your doctor to view the mucosal lining of your lower gastrointestinal tract.

The procedure is used as a screening test in individuals with no symptoms, or to help diagnose unexplained abdominal pain, rectal bleeding, or a change in bowel habits.

It is capable of detecting inflammation, infections, ulcers, diverticulosis, intestinal narrowing, colorectal polyps, cancer or other problems that may be present.

The procedure is performed using an endoscope, which is a long, thin, flexible tube with a light and a tiny video camera attached to the end. The camera transmits an image to a monitor.

In a sigmoidoscopy, the endoscope only reaches to the top of the descending colon.

In a colonoscopy, the endoscope reaches through the entire length of the colon to where it connects to the small intestine.

Before a colonoscopy, an intravenous line will be started and you will be offered pain medication and a sedative.

Your blood pressure, pulse, and the oxygen level in your blood will be monitored and you may also receive oxygen through a nasal cannula during the procedure.

A sigmoidoscopy does not usually require this kind of preparation or monitoring.

The presence of the endoscope and the air may cause you to feel cramping or pressure and the need to pass gas.

This is considered a normal part of the procedure.

Your doctor may ask you to change your position slightly to help maneuver the endoscope more easily through the curves of your lower intestine.

If you experience pain tell your doctor immediately.

In some cases, your doctor may find it necessary to take a biopsy.

A biopsy helps distinguish between benign and cancerous tissues and can help determine the cause of bleeding, inflammation or diarrhea.

Biopsies are often taken even when your doctor does not suspect cancer.

If one or more polyps are discovered, your doctor will generally remove them in a procedure called a polypectomy.

He or she will usually use a snare to remove the polyps and then cauterize their bases to control bleeding.

After the procedure you will be monitored for about half an hour until the effects of any medications you have taken wear off.

You will need to arrange for a ride home, particularly after a full colonoscopy.