A flexible sigmoidoscopy is a visual exam of the rectum and the lower portion of the colon, called the sigmoid colon, with an instrument called a flexible sigmoidoscope. This instrument shines light and allows the doctor to view the inside of the intestine (bowel) through a tiny video camera. Sigmoidoscopy can also be used to obtain tissue samples for testing.

Parts of the body involved:

Sigmoid colon, rectum,

Reasons for the procedure:

Flexible sigmoidoscopy examines and diagnoses problems inside the rectum and the sigmoid colon. The procedure is most often performed for the following reasons:

  • Screen for colorectal cancer (recommended every three to five years for all people over 50, and earlier and more frequently for people with a family history of colon cancer or certain bowel diseases, such as intestinal polyps, Crohn's disease or ulcerative colitis)
  • Obtain a tissue sample for biopsy
  • Identify the source of rectal bleeding, diarrhea, constipation, pain or inflammation
  • Detect the presence of polyps (small growths than can turn cancerous)
  • Monitor response to treatment in patients with inflammatory bowel disease
  • In pediatric patients, this procedure can identify causes of rectal bleeding, such as internal fissures, polyps and allergic colitis

Risk factors that may lead to complications:

  • Pre-existing severe heart or kidney condition
  • Treatment with certain medications, including aspirin and other drugs with anticoagulant or "blood-thinning" properties
  • The patient is unable to cooperate
  • Acute, severe abdominal pain due to a bowel perforation or another serious, acute intestinal condition
  • Prior abdominal surgery or radiation treatments

What to expect before the procedure:

  • Physical and rectal exam
  • Health history
  • Evaluation of all medications taken
  • Test to check for hidden blood in your stool called "occult blood"

In the days leading up to your procedure:

Your lower intestine must be completely cleaned out before the procedure. Any stool left in the intestine will block the doctor's view. This preparation may start several days before the procedure. Follow your doctor's instructions, which may include any of the following cleansing methods:

  • Enemas (fluid introduced into the rectum to stimulate a bowel movement)
  • Laxatives
  • A clear liquid diet
  • Oral cathartic medications (a large container of fluid to drink, which stimulates a bowel movement)

Ask when making the appointment about any medication restrictions; you may need to stop taking anti-inflammatory and blood-thinning medications, including aspirin and ibuprofen, seven to 10 days before the procedure.

You may also need to stop taking iron supplements or vitamins containing iron.

The night before, eat a light meal and do not eat or drink anything after midnight.

Wear comfortable clothing.

During the procedure:

You'll be positioned on your left side with knees bent and drawn up toward your chest, on your back with your feet in stirrups (as for a pelvic examination) or on a special table. Try to relax and breathe slowly and deeply.


For pediatric patients, the decision to use anesthesia is made on an individual basis. Discuss this with your doctor.

Description of the procedure:

The doctor first performs a digital rectal exam. Then the doctor slowly inserts the lubricated sigmoidoscope, which is about the thickness of a human finger, through the rectum and into the colon. The scope injects air into the colon to widen the passage. The doctor guides the instrument through the lower colon and examines the lining, looking for abnormalities. A small video camera in the sigmoidoscope lets the doctor view an image of the colon's lining and rectum. A tissue sample and/or intestinal polyps may be removed and analyzed.

After the procedure:

Laboratory exam of the removed tissue.

How long will it take?

20 to 30 minutes.

Will it hurt?

  • Most patients report discomfort when the instrument is inserted, as well as cramping, muscle spasms or lower abdominal pain during the procedure. You may also feel the urge to move your bowels. Tell the doctor if you experience severe pain.
  • After the procedure, gas pains and cramping are common but should subside with the passing of gas.

Possible complications:

  • Bleeding
  • Perforation or puncture of the bowel
  • Patients with pre-existing heart murmurs or known heart valve disease may be susceptible to infection after this examination and may be given antibiotics to prevent infection.

Average hospital stay:


Postoperative care:

  • If tissue was removed, a small amount of bleeding may occur during the first few days after the procedure.
  • Resume medications as instructed by your doctor.
  • Resume a normal diet unless directed otherwise by your doctor.
  • If you're given antibiotics, finish the entire prescription.


After removing the sigmoidoscope, the doctor will usually give a preliminary report. Depending on what your doctor finds, a complete colonoscopy may be recommended. A colonoscopy is a similar procedure using a flexible instrument that goes further into your colon than the sigmoidoscope. With this procedure, your entire colon can be examined, and polyps or other small growths can be removed for a biopsy. It may take one to two weeks for the results of a biopsy.

Call your doctor if any of the following occurs:

  • Bleeding from your rectum (notify your doctor if you pass a teaspoon or more of blood)
  • Black stools
  • Severe abdominal pain
  • Hard, swollen abdomen
  • Signs of infection, including fever or chills
  • Nausea
  • Inability to pass gas or stool