Sigmoidoscopy is a procedure that is conducted to examine the rectum of the body. A small chamber, it begins at the end of the large intestine followed by the sigmoid colon, and the rectum ends at the anus. The test helps the doctor to view the sigmoid colon which is a terminal section of the large intestine besides also getting a clear view of the rectum. During this process, the medical practitioner uses a viewing tube consisting of a light and a small lens on one end, and an eyepiece on the other end called a sigmoidoscope. Through the procedure (also popularly known as flexible sigmoidoscopy), the doctors look for signs of inflammation, ulcers, colon cancer, and polyps through the process of transmitting light through minute strands of optical fiber. The procedure is sometimes a tad bit discomforting but most likely a pain-free one with no recovery time unless a rare complication may arise.

Also Read: Ulcerative Colitis: Types, Symptoms And Treatment

When Is Sigmoidoscopy Advised?

Sigmoidoscopy helps to determine the cause of many symptoms. Depending on the patient’s health and history or co-morbid conditions, and when in some cases when there has been a history of colorectal cancer in the family, doctors may advise frequent sigmoidoscopy to the patients who are aged fifty or above. Sigmoidoscopy is also suggested in case the following symptoms are seen:

  • Sporadic change in bowel habits due to temporary infection, celiac disease, or chronic constipation
  • Colon cancer that could appear in the form of polyp inside the rectum
  • Pain in the abdomen which could be due to indigestion, infection, injury, or a disease
  • Sudden and unexplained weight loss
  • Bleeding in the rectum that may occur due to haemorrhoids or an anal fissure

Also Read: Anal Fissures: Causes, Symptoms And Treatment

Preparing For A Sigmoidoscopy

Preparing for a sigmoidoscopy is not very difficult.  A few weeks before the test, medications with the attending physician should be discussed in detail. Enemas (injections to cleanse or stimulate pressure of the bowel) are given to the patient before the procedure and the following guidelines are to be followed for sigmoidoscopy:

  • Avoid eating or drinking anything the night before sigmoidoscopy as food and liquids can interfere with the view of the sigmoidoscope which may hamper the results
  • Patients with diabetes, people taking blood thinners, or people on iron supplements may be advised to temporarily stop consuming them
  • A low-fiber diet is advised two to three days before the exam. The purpose of this diet is to produce smaller bowel movements that eventually assist the colon to get ready for sigmoidoscopy
  • Since there are chances that the residue inside the rectum or colon may produce unclear sigmoidoscope images, a laxative may be given a day before the test to clear the remaining residue sitting in the colon

Diet Restrictions Before A Sigmoidoscopy

In most cases the colon needs to be clear for obtaining precise results, therefore the doctor advises a clear liquid diet a few days before the procedure. Liquids that can be taken during this time are plain water, tea, coffee, a clear soup, and a few recommended sports drinks that contain essential electrolytes. There is a very strict instruction to avoid liquid with red color additive, pigment, or a substance because it can look like blood in the colon and give distorted results.

What Should One Expect After The Procedure?

After a sigmoidoscopy procedure, the patient does not need to stay at the clinic or hospital and can resume their activities as well as eat normal food. Results of the test are usually available within a few days after the procedure. Chances of little discomfort after the test may arise because of the air that gets pushed into the colon during this test. The doctor may also discuss results with the patient about the next steps to be followed and may recommend a biopsy in case any polyps are found. In some cases, a colonoscopy to examine the entire colon is also recommended.


Sigmoidoscopy or flexible sigmoidoscopy procedure is a simple, minimally invasive procedure to examine the lower part of the colon, called the sigmoid colon. The test is done using a thin tube with a light and small video camera attached to it known as a sigmoidoscope and is inserted into the anus. The device can capture images from the lower colon for detailed examination. A potent way to diagnose polyps, colon diseases, or colon cancer, the physician may recommend a sigmoidoscopy when a patient may have frequent episodes of abdominal pain, bowel habit changes, bleeding of the rectum, or persistent diarrhea. Though sigmoidoscopy is a pain-free experience with no recovery time, the patient may experience some discomfort during or after the procedure.