Lower endoscopy, also called colonoscopy or sigmoidoscopy, allows the doctor to view the mucosal lining of the lower gastrointestinal tract. The doctor uses this procedure as a screening test in individuals with no symptoms or to help diagnose unexplained abdominal pain, rectal bleeding or a change in bowel habits.
A doctor can perform lower endoscopy to detect inflammation, infections, ulcers, diverticulosis, intestinal narrowing, colorectal polyps, cancer or other problems that may be present.
The doctor performs the procedure using an endoscope, which is a long, thin and flexible tube with a tiny light and camera attached to the end. The camera transmits an image to the monitor.
During a sigmoidoscopy, the endoscope only reaches the top of the descending colon. However, during colonoscopy, the endoscope reaches through the entire length of the colon to where it connects to the small intestine.
Before a colonoscopy, you are given an intravenous line and pain medication. The doctor monitors your blood pressure, pulse, and oxygen level in your blood. You may also be given oxygen through a nasal cannula during the procedure.
Usually, sigmoidoscopy does not need this kind of preparation or monitoring. Due to the presence of the endoscope and the air, you may feel cramping or pressure and the need to pass gas.
However, this is considered a normal part of the procedure. The 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 feel pain, do tell your doctor immediately. In some cases, the doctor may find it necessary to take a biopsy. A biopsy helps the doctor distinguish between benign and cancerous tissues and determine the cause of bleeding, inflammation or diarrhea.
Usually, biopsies are taken when the doctor does not suspect cancer. If one or more polyps are detected, the doctor generally removes them during a procedure called a polypectomy. The doctor uses a snare to remove the polyps and then cauterized their bases to control bleeding.
After completion of the procedure, the doctor monitors you for half an hour until the effects of any medications you have taken wear off. After that, you are discharged from the hospital.