Rigid and Flexible Sigmoidoscopy

There are various differences between flexible sigmoidoscopy and rigid sigmoidoscopy

Apart from the length, the flexible sigmoidoscope is more flexible to maneuver. Thus, it produces less discomfort. The rigid sigmoidoscopy has a lesser diagnostic yield than the flexible sigmoidoscopy. 

Other differences between flexible sigmoidoscopy and rigid sigmoidoscopy are:

• Rigid sigmoidoscopy can cause discomfort
• Rigid sigmoidoscopy is time-consuming
• Flexible sigmoidoscopy has better tolerance
• Ease of obtaining tissue biopsies in flexible sigmoidoscopy
• A restricted view of the rectum and colon is seen in rigid sigmoidoscopy

Sigmoidoscopy is a procedure to examine the lower part of the large intestine (rectum and the lower colon). It is a short procedure lasting for about 5 to 10 minutes.

Sigmoidoscopy is used to diagnose:

• polyps (small abnormal growth, which may become cancerous)
• colon cancer 
• rectal cancer
• inflammation (swelling)
• bleeding
• hemorrhoids

An instrument known as a sigmoidoscope is used in the sigmoidoscopy. A sigmoidoscope is of two types:

• Rigid sigmoidoscope: This sigmoidoscope is 25 cm long, and it allows examination of up to about 20 cm of the rectum and colon.
• Flexible sigmoidoscope: It is made of a flexible fiber-optic tube and can be up to 60 cm long. It allows examination of the descending colon.

Rigid sigmoidoscopy is mainly advised in the following conditions:

• Symptoms suggestive of the colon or rectal cancer
• Before any surgery of anus or colon
• For performing a biopsy of any bowel disease, which is within the reach of the instrument
• Assessing the length of rectal cancer (distance from the anal end)
• As a control treatment in case of abnormal twisting of the bowel (sigmoid volvulus)

There are two reasons for avoiding rigid sigmoidoscopy: Absolute and relative.

Absolute reasons are:

• Suspected or known perforation (hole in the wall) of the small intestine
• Anal stenosis (narrowing of the anal canal that makes it difficult to pass the stool)

Relative reasons are:

• Acute peritonitis (inflammation of the lining of the abdominal wall)
• Uncooperative, anxious or agitated patients
• Acute inflammatory disease of the anus
• Recent surgery of the colon
• Fulminant colitis (a rare and serious form of inflammation and sores over the lining of the colon)
• Toxic megacolon (a potentially deadly complication of colonic inflammation)
• Anal fissure (small tear in the lining of the anus)
• Severe coagulopathy (impaired clot formation)
• Severe thrombocytopenia (decreased platelet count)
• Severe neutropenia (decreased neutrophil count of white blood cell)

Rigid sigmoidoscopy can be performed either in a hospital or in an outpatient setting. Your doctor may share detailed instructions to help you prepare for the surgery, which involves:

• Following a liquid diet for up to 24 hours before the examination.
• Emptying the colon on the previous night or the day of surgery, with the help of an enema or strong laxatives.
• Detailing medical and medication history, especially any medication allergy to your doctor.

Rigid sigmoidoscopy is mostly performed without anesthesia. The doctor will ask you to lie on your side on the examination table. Once you lie down, the doctor will perform a digital anal examination to check for any abnormalities. Next, the doctor will gently insert the lubricated scope into the anus. The doctor will use the scope to blow air into your colon and to inflate it, as the procedure advances. This makes it easier for the doctor to examine. In the end, the scope is gently removed, and the anal area is cleaned.

Generally, this procedure produces some discomfort; however, it is not painful. If you feel pain at any time during the surgery, you need to immediately inform the doctor.

You can perform your normal activities after the surgery.

• You may experience cramps or bloating for a few days, which may pass away quickly.
• You may release gas that was put into the colon during the procedure.
• You may experience diarrhea and minor bleeding from the rectum.

Contact your physician immediately, in case you have these symptoms:

• Major bleeding
• Dizziness
• Weakness
• Fever