Rigid Sigmoidoscopy Technique

Updated: Mar 28, 2022
  • Author: Iman Bayat, MBBS, MRCS(Eng), FRACS(Vasc); Chief Editor: Vikram Kate, MBBS, MS, PhD, FACS, FACG, FRCS, FRCS(Edin), FRCS(Glasg), FFST(Ed), FIMSA, MAMS, MASCRS  more...
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Rigid Sigmoidoscopy

With the patient in position, assemble the rigid sigmoidoscope (see the video and image below). Check that the light source is functioning by connecting it to a power source. Connect the bellows’ tubing to an intercepting disposable air filter. Remove the stylet from the scope. Connect the light source, bellows–air filter, and scope to the eyepiece. Open the eyepiece window and insert the stylet through the eyepiece into the scope, ensuring that the tip of the stylet protrudes through the tip of the scope. Apply generous amounts of a water-based lubricant to the scope.

Assembly of rigid sigmoidoscope.
Assembled rigid sigmoidoscope. Photo courtesy of V Assembled rigid sigmoidoscope. Photo courtesy of Vicki Adams, Senior Medical Photographer, Mater Health Services Multimedia team.

Inspect the anus and surrounding areas for any abnormalities. Next, perform a digital rectal examination (DRE; see the video below). A DRE must always be done before rigid sigmoidoscopy. Make special note of the general anatomy of the distal rectum, any palpable lesions, and the contents of the rectum. If the rectum is found to be loaded with feces, an attempt should be made to empty the rectum with the aid of a laxative suppository or enema before performing rigid sigmoidoscopy.

Digital rectal examination preceding sigmoidoscopy.

Hold the scope with the thumb, pushing on the base of the stylet to hold it in place (see the video below). Insert the scope 4 cm into the anus in the direction of the patient’s umbilicus. At this point, remove the stylet, and seal the eyepiece with the glass window.

Insertion of rigid sigmoidoscope and removal of stylet.

Once the stylet is removed, advance the scope under direct vision, using the bellows to gently insufflate air into the rectum intermittently as the scope advances. Knowledge of the three-dimensional anatomy of the rectum is important.

At 4 cm from the anus, the rectum angulates posteriorly over the puborectalis sling into the hollow of the sacrum (see the image below).

Basic anatomy of rectum. Basic anatomy of rectum.

Therefore, when the scope reaches this point 4 cm from the anus, its general direction should change from pointing anteriorly to pointing posteriorly (see the video below).

Rigid sigmoidoscopy. Proper positioning and anatomy of patient.

Gently insufflate air into the rectum to expand the rectum in front of the scope. Under direct vision, advance the scope into the middle of the expanded segment. Repeat the insufflate-advance steps as the scope moves along. Note any abnormalities. A slight lateral angulation of the scope is used to maneuver through the rectal valves (see the image below).

Maneuvering through rectal valves. Maneuvering through rectal valves.

At the 12 cm level, the sacral promontory produces a sharp angulation of the rectum anteriorly. At this point, the direction of the scope is changed to point anterosuperiorly.

The usual distance that can be examined comfortably is 15-20 cm. Any significant pain is an indication to terminate the examination. Further examination may be performed using a flexible scope.

As the scope is withdrawn, follow the above steps backward. Insufflate air and change directions while maintaining direct vision of the lumen of the rectum. Small circular motions allow a more complete examination and may reveal lesions missed during insertion of the scope.

Upon complete removal of the scope, wipe off the perianal area and return the patient to a more comfortable position.

Concerns have sometimes been expressed that because rigid sigmoidoscopy involves insufflation of air into the rectum, with the sigmoidoscopist's face 5-20 cm from the patient's anus, the air escaping from the anus may contaminate the examiner's face with fecal flora; however, a small study by Skittrall et al found there to be no clinically significant contamination in this scenario. [22]



Rigid sigmoidoscopy performed by trained clinicians is tolerated by most patients and has a low incidence of serious complications. However, some adverse effects and complications do occur.

Among patients who undergo rigid sigmoidoscopy, 60% report adverse effects. Most of these reported adverse effects are of low magnitude. [23] As many as 30% of patients experience moderate-to-severe discomfort during rigid sigmoidoscopy. [24] The following types of discomfort are commonly reported:

  • Pain (33%)
  • Discomfort from rectal preparation (13%)
  • Uncomfortable desire to defecate (8%)
  • Discomfort associated with patient positioning (4%) [23]

Negotiating the rectosigmoid angle as the rigid sigmoidoscope is inserted to a depth of 20 cm is the most likely cause of major patient discomfort, though insufflations of the rectum may also contribute to discomfort. [1]

Significant bleeding that necessitates transfusion or further procedural intervention occurs in approximately 1 out of 9400 rigid sigmoidoscopies. [25] This complication is usually related to concomitant rectal biopsy. [25]

Bacteremia occurs in 5% of patients during rigid sigmoidoscopy, which justifies the precaution for its use in patients with neutropenia. [26]