The sigmoid colon lies in the lower part of the colon or large stomach. Diagnosis of the diseases related to this area diagnosed using sigmoidoscopy.  This part of the colon is next to the anus and rectum.

Following are diagnosable by sigmoidoscopy:

  • Diarrhea
  • Belly pain
  • Constipation
  • Polyps (abnormal growths)
  • Bleeding

If there is any suspicion of carcinoma or any other disease, tissue sampling is possible with the help of sigmoidoscopy. Excision of growth is also possible.

This is also a screening procedure for cancer of the colon and of the rectum.

Why is sigmoidoscopy required?

Identification of the following is possible:

  • Polyps
  • Tumors
  • Ulcers (sores)
  • Inflammation (redness and swelling)
  • Hemorrhoids
  • Diverticula (pouches on your colon wall)
  • Strictures (narrowing of your lower colon)

The following can also be identified:

  • Changes in your bowel habits
  • Lower belly pain
  • Itching around your anus
  • Blood or mucus in your stool
  • Low iron levels
  • Low blood counts

Screening for carcinoma of the rectum or the colon can be done by sigmoidoscopy. People over 50 should get the screening done regularly.

Based on certain clinical conditions, the physician may recommend a colonoscopy.

Preparation for sigmoidoscopy?

The paramedical staff helps in bowel preparation. Instructions about diet and fasting will be given.

Inform the physician if:

  • the patient is pregnant
  • allergic to any medication
  • taking any additional medication
  • having any comorbid conditions
  • bleeding disorders or taking any anticoagulants

During sigmoidoscopy?

In an ambulatory setting, or as part of a hospital stay, sigmoidoscopy can be performed. The pattern of examination is procedure dependent. Usually, this procedure does not require any sedation or anesthetic agent.

Preparation and Positioning

With the patient lying to the left side, the legs are pulled towards the chest and the position is secured for the procedure.

Procedure of performing sigmoidoscopy

  1. The first step involves the rectal examination for the presence of any blood, mucus, or stool. The scope is passed through the dilated anus.
  2. The examination of sigmoid region is done.
  3. The air is blown for improving the visibility inside the bowel. Any loose stool is suctioned out.
  4. Small surgical instruments are pushed through the sigmoidoscope for taking a biopsy, or excision of a polyp, or to stop the bleeding.

After a sigmoidoscopy?

Before getting up from the patient bed, lie down on the back or side for a few minutes and then slowly get up and then stand, this makes the patient feel less dizzy.

In general, the patient is able to get back to routine work or have normal food, but in some cases it is different. During the bowel movements after a biopsy, some blood is visible but usually subsides by itself.

Patients may pass a lot of gas and experience pain due to gas. Ambulation will help reduce this pain.

Side effects

Side effects include:

  • cramping or discomfort in the lower abdomen
  • bloating
  • gas
  • diarrhea
  • bleeding from the rectum

In very few instances, there may be a puncture in the colon due to the procedure, which will need corrective surgery.


An abnormal outcome may show:

  • hemorrhoids
  • polyps
  • diverticulosis
  • inflammatory bowel disease, such as ulcerative colitis
  • cancer of the colon or rectum

In case of abnormal outcome, additional procedures or investigations may be recommended.

Risks and limitations

The risk associated with this procedure is very less.

When to obtain care

If the patient experiences any of the following, should seek medical advice immediately:

  • severe pain in your abdomen
  • fever
  • continued bleeding from your anus
  • dizziness
  • weakness
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