Flexible Sigmoidoscopy

Similar to colonoscopy, flexible sigmoidoscopy is performed by doctors to evaluate the large intestine or colon. Using a long, flexible tube about as big in diameter as your pinky finger, a physician can look inside the last third of the colon (the rectum and sigmoid colon). The tube has a video camera as well as a bright light so the physician can inspect the inside of the colon. The scope has a channel through which instruments can be placed to take biopsies or remove polyps. Flexible sigmoidoscopy can detect inflamed tissue, abnormal growths, and ulcers. This procedure is commonly performed to look for early signs of cancer and can help doctors evaluate symptoms such as diarrhea, rectal bleeding, changes in bowel habits, abdominal pain, and weight loss. 

Unlike colonoscopy, flexible sigmoidoscopy doesn't require an oral preparation and can be performed without sedation in 3 - 5 minutes. However, colonoscopy is the preferred method for screening patients for cancers of the large intestine. Typically, flexible sigmoidoscopy is performed when a complete colonoscopy is unnecessary. 

Prep Instructions

  1. Do not eat or drink anything, including water, for four (4) hours prior to your examination.
  2. Obtain two (2) Fleets Enemas from your pharmacy. Use them according to the package directions.
  3. Use the first enema two (2) hours before you need to leave your home.
  4. Use the second enema one (1) hour before you need to leave your home.

Additional Information

How to prepare for a flexible sigmoidoscopy.

Flexible sigmoidoscopy requires cleansing only the last third of the colon. This is usually accomplished with two enemas preformed two hours before the exam. An enema is performed by flushing a solution, usually salty but sometimes a mild soapy solution, into the anus using a special bottle with a tapered tip. Occasionally, a full colonoscopy preparation is utilized. If you have renal failure, the over-the-counter salty enema (Fleets) should not be used. 

Please inform your physician if you are taking any of the following medications as they may need to be discontinued in advance of the procedure: 

  • Aspirin
  • Arthritis medications
  • Blood thinners
  • Diabetes medications
  • Any iron containing supplements

How is a flexible sigmoidoscopy performed?

After checking in at the time specified on our instructions, you will be asked a series of questions. Afterward, you will be wheeled into the exam room on a gurney. Your doctor will then gently insert a flexible endoscope through the anus and through the sigmoid colon. The scope will then be slowly withdrawn inspecting the sigmoid colon and rectum. In many cases, your doctor may be able to pass the scope as far as the mid-point of the colon, or the transverse colon. 

Most patients will undergo this exam while they are unsedated. The exam lasts about 3-5 minutes. An unsedated patient will experience some discomfort like a gas cramp as air is passed into the intestine and as the scope navigates several turns. Any discomfort usually resolves as the scope is withdrawn. Most patients are encouraged to breathe deeply and try to relax as this makes the exam easier for both the patient and the physician.

Removal of polyps and biopsy

While the scope is withdrawn, polyps can be removed if they are found. Your doctor can use thin instruments through the channel in the scope to separate and then remove any polyps that are identified. However, if polyps are found, a full colonoscopy is usually warranted. Therefore, polyps may be left in place until the colonoscopy is performed. 

Should inflammation be seen or suspected, your doctor can perform simple biopsies of the lining of the intestine. Both the removal of biopsies and polyps are painless.


Cramping or bloating may occur in the first hour following the completion of the exam. This typically resolves quickly but occasionally a patient may experience some soreness for a day or two. 

Should you develop any of the following symptoms afterwards contact your doctor immediately: 

  • Severe abdominal pain
  • Fever
  • Bloody bowel movements
  • Dizziness
  • Weakness