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Sigmoidoscopy is a medical procedure in which the physician is able to visualize the inside walls of the large intestine with a scope placed in the rectum. Only the distal part of the colon, or the sigmoid, is examined as opposed to the entire bowel in a colonoscopy.

Reasons for procedure

The use of this procedure is mainly for early detection of colorectal cancer, vascular abnormalities or polyps. Studies have shown that this procedure has aided in early detection of colorectal cancer and improved survivor rates. Sigmoidoscopy may also be utilized in cases of unexplained diarrhea, constipation or pain.

Types of sigmoidoscopes

Rigid and flexible are the two types of sigmoidoscopy. The names indicate the difference between the two and the type used is determined by the physician. The rigid sigmoidoscope can give a limited view but does well with rectally located issues such as bleeds.

The flexible sigmoidoscope is the preferred type. With the design of this scope, more surface area can be explored with less pain to the patient. The physician is able to visualize benign and malignant polyps, as well as abnormal cells in the descending colon and rectum. Other problems such as intestinal bleeding, inflammation and ulcers in the descending colon and rectum can also be identified.


Due to the nature of the exam, the patient is instructed to not eat anything for 12-24 hours before the procedure. They are given a clear liquid diet that they should adhere to for an entire day before the procedure. Other measures such as laxatives or enemas may be employed to give the best exam for the patient.

Once the patient is ready, the patient will lie on their left side on the table. The physician will insert the sigmoidoscope into the rectum. As the scope moves forward, air is expelled from the end of the scope in order for a better view of the walls. The patient will feel pressure or cramping during the event but this should subside once air is removed. The physician will view for any type of abnormal findings. If a polyp or abnormal tissue is found, the physician has the ability to gather a biopsy with the scope.  The procedure should last from 10-20 minutes.

Possible problems

The largest complication, which is rare to occur, is a tear in the intestinal wall by the instrument. There could also be bleeding at the site of a polyp removal or biopsy site. Both can be repaired surgically with good outcome.