Sigmoidoscopy
Flexible sigmoidoscopy; Sigmoidoscopy - flexible; Proctoscopy; Proctosigmoidoscopy; Rigid sigmoidoscopy; Colon cancer sigmoidoscopy; Colorectal sigmoidoscopy; Rectal sigmoidoscopy; Gastrointestinal bleeding - sigmoidoscopy; Rectal bleeding - sigmoidoscopy; Melena - sigmoidoscopy; Blood in stool - sigmoidoscopy; Polyps - sigmoidoscopySigmoidoscopy is a procedure used to see inside the sigmoid colon and rectum. The sigmoid colon is the area of the large intestine nearest to the rectum.
How the Test is Performed
During the test:
- You lie on your left side with your knees drawn up to your chest.
- Your health care provider gently places a gloved and lubricated finger into your rectum to check for blockage and gently enlarge (dilate) the anus. This is called a digital rectal exam.
Digital rectal exam
A digital rectal exam is an exam of the lower rectum. Your health care provider uses a gloved, lubricated finger to check for any abnormal findings....
Read Article Now Book Mark Article - Next, the sigmoidoscope is placed through the anus. The scope is a flexible tube with a camera at its end. The scope is gently moved into your colon. Air is inserted into the colon to enlarge the area and help the provider view the area better. The air may cause the urge to have a bowel movement or pass gas. Suction may be used to remove fluid or stool.
- Often, the images are seen in high definition on a video monitor.
- The provider may take tissue samples with a tiny biopsy tool or a thin metal snare inserted through the scope. Heat (electrocautery) may be used to remove polyps if your colon has been properly prepared for this. Photos of the inside of your colon may be taken.
Biopsy
A biopsy is the removal of a small piece of tissue for laboratory examination.
Read Article Now Book Mark ArticlePolyps
A colorectal polyp is a growth on the lining of the colon or rectum.
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Sigmoidoscopy using a rigid scope may be done to treat problems of the anus or rectum.
How to Prepare for the Test
Your provider will tell you how to prepare for the exam. You will use an enema to empty your bowels. This is usually done 1 hour before the sigmoidoscopy. Often, a second enema may be recommended or your provider may recommend a liquid laxative the night before.
On the morning of the procedure, you may be asked to fast with the exception of certain medicines. Be sure to discuss this with your provider well in advance. Sometimes, you are asked to follow a clear liquid diet the day before, and sometimes a regular diet is allowed. Again, discuss this with your provider well in advance of your test date.
How the Test will Feel
During the exam you may feel:
- Pressure during the digital rectal exam or when the scope is placed in your rectum.
- The need to have a bowel movement.
- Some bloating or cramping caused by the air or by stretching of the bowel by the sigmoidoscope.
After the test, your body will pass the air that was put into your colon.
Children may be given medicine to make them sleep lightly (sedated) for this procedure.
Why the Test is Performed
Your provider may recommend this test to look for the cause of:
- Abdominal pain
- Diarrhea, constipation, or other changes in bowel habits
- Blood, mucus, or pus in the stool
- Weight loss that can't be explained
This test can also be used to:
- Confirm findings of another test or x-rays
-
Screen for colorectal cancer or polyps
Colorectal cancer
Colorectal cancer is cancer that starts in the large intestine (colon) or the rectum (end of the colon). It is also sometimes simply called colon ca...
Read Article Now Book Mark Article - Take a biopsy of a growth
All adults should have a colon cancer screening test starting at age 45. For people with an average risk for colon cancer, flexible sigmoidoscopy every 5 years or every 10 years plus stool testing with FIT done every year is one screening option.
Screening option
Colon cancer screening can detect polyps and early cancers in the large intestine. This type of screening can find problems that can be treated befo...
Read Article Now Book Mark ArticleNormal Results
A normal test result will show no problems with the color, texture, and size of the lining of the sigmoid colon, rectal mucosa, rectum, and anus.
What Abnormal Results Mean
Abnormal results can indicate:
- Anal fissures (small split or tear in the thin, moist tissue lining the anus)
Anal fissures
An anal fissure is a small split or tear in the thin moist tissue (mucosa) lining the lower rectum (anus).
Read Article Now Book Mark Article - Anorectal abscess (collection of pus in the area of the anus and rectum)
Anorectal abscess
An anorectal abscess is a collection of pus in the area of the anus and rectum.
Read Article Now Book Mark Article - Blockage of the large intestine, such as a mechanical blockage or Hirschsprung disease
Blockage of the large intestine
Intestinal obstruction is a partial or complete blockage of the bowel. The contents of the intestine cannot pass through it.
Read Article Now Book Mark ArticleHirschsprung disease
Hirschsprung disease causes a blockage of the large intestine. It occurs due to poor muscle movement in the bowel. It is a congenital condition, wh...
Read Article Now Book Mark Article - Cancer
- Colorectal polyps
Colorectal polyps
A colorectal polyp is a growth on the lining of the colon or rectum.
Read Article Now Book Mark Article - Diverticulosis (abnormal pouches on the lining of the intestines)
Diverticulosis
Diverticulosis occurs when small, bulging sacs or pouches form on the inner wall of the intestine. These sacs are called diverticula. Most often, t...
Read Article Now Book Mark Article - Hemorrhoids
Hemorrhoids
Hemorrhoids are swollen veins in the anus or lower part of the rectum.
Read Article Now Book Mark Article - Inflammatory bowel disease
- Inflammation or infection (proctitis and colitis)
Proctitis
Proctitis is an inflammation of the rectum. It can cause discomfort, bleeding, and the discharge of mucus or pus.
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Risks
There is a slight risk of bowel perforation (tearing a hole) and bleeding at the biopsy sites. The overall risk is very small.
References
Rex DK, Boland CR, Dominitz JA, et al. Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol. 2017;112(7):1016-1030. PMID: 28555630 www.pubmed.ncbi.nlm.nih.gov/28555630/.
Sugumar A, Vargo JJ. Preparation for and complications of gastrointestinal endoscopy. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 42.
US Preventive Services Task Force website. Final recommendation statement. Colorectal cancer screening. www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening. Published May 18, 2021. Accessed November 25, 2022.
Wang KK. Gastrointestinal endoscopy. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 120.
Colonoscopy - illustration
There are 3 basic tests for colon cancer; a stool test (to check for blood), sigmoidoscopy (inspection of the lower colon), and colonoscopy (inspection of the entire colon). All 3 are effective in catching cancers in the early stages, when treatment is most beneficial.
Colonoscopy
illustration
Sigmoid colon cancer - X-ray - illustration
A barium enema in a patient with cancer of the large bowel (sigmoid area).
Sigmoid colon cancer - X-ray
illustration
Rectal biopsy - illustration
Rectal biopsy can be used to determine the cause of blood, mucus, or pus in the stool. Rectal biopsy can also confirm findings of another test or x-rays, or take a biopsy of a growth found in the colon.
Rectal biopsy
illustration
Colonoscopy - illustration
There are 3 basic tests for colon cancer; a stool test (to check for blood), sigmoidoscopy (inspection of the lower colon), and colonoscopy (inspection of the entire colon). All 3 are effective in catching cancers in the early stages, when treatment is most beneficial.
Colonoscopy
illustration
Sigmoid colon cancer - X-ray - illustration
A barium enema in a patient with cancer of the large bowel (sigmoid area).
Sigmoid colon cancer - X-ray
illustration
Rectal biopsy - illustration
Rectal biopsy can be used to determine the cause of blood, mucus, or pus in the stool. Rectal biopsy can also confirm findings of another test or x-rays, or take a biopsy of a growth found in the colon.
Rectal biopsy
illustration
Review Date: 7/30/2022
Reviewed By: Michael M. Phillips, MD, Emeritus Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Internal review and update on 07/16/2023 by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.