5 differences between colonoscopy and sigmoidoscopy

As specialists, Triborough GI offers many important and trusted diagnostic and screening services from our four area offices in Bushwick, Brooklyn, the Bronx, and Staten Island, New York. These services include colonoscopy and flexible sigmoidoscopy. While both of these tests use a thin tube and camera to check for problems with the colon, there are key differences between them. We have highlighted five areas where these procedures differ below.

1 – Parts of the colon that are examined 

A colonoscopy examines your entire colon or large intestine. Flexible sigmoidoscopy is used to evaluate the rectum and the part of the colon that is closest to the anus (the sigmoid colon) – not the entire colon. 

2 – Preparation 

Proper colon cleansing is essential before a colonoscopy. This involves drinking a prescribed bowel prep and following other dietary instructions provided by our team. Failure to follow these instructions affects how well you cleanse and, in turn, our ability to see the inside of the colon.  Sigmoidoscopy may involve taking cleansing enemas or bowel prep as directed by your doctor. Usually, preparation for sigmoidoscopy is less extensive than preparing for a colonoscopy.

3 – Anesthesia/sedation

A colonoscopy is performed with an anesthetic medication for your comfort. It is administered through an intravenous catheter. While anesthesia or sedation can be helpful for some patients, it is not always required for a sigmoidoscopy. 

4 – Recovery 

The colonoscopy procedure is associated with lingering drowsiness due to the medications that are administered for your comfort. We generally have patients relax in our recovery room until these effects wear off and it’s safe enough for them to go home. These lingering effects may be avoided with sigmoidoscopy, since this service doesn’t always require anesthesia or sedation. Colonoscopy is a longer and more invasive, and involved procedure than sigmoidoscopy, so the recovery afterward reflects this. With sigmoidoscopy, you can generally get back to your usual activities right away. With a colonoscopy, we ask that you take it easy for the rest of the day. Here again, it is important to follow all instructions provided by our team and specific to your procedure and needs.  

5 – Candidates

Colonoscopy is recommended as part of routine screening for colon and rectum (colorectal) cancers. The frequency of these screenings is based on your age and risk factors, which include a personal history of these cancers and syndromes associated with widespread polyps. These small growths have the potential to turn into cancer. Colonoscopy may also be used to investigate potential causes of unexplained digestive symptoms, such as bleeding and persistent stomach upset. It is also a preventive procedure, as we can biopsy or remove polyps during your appointment. Colonoscopy may also follow sigmoidoscopy if polyps or other abnormalities are found during your test. 

Sigmoidoscopy, too, may be used to screen for cancer and to uncover the potential cause of changes in bowel habits and other symptoms. However, this test is recommended when the symptoms suggest that the issue is localized to the lower colon. For appropriate patients, sigmoidoscopy also presents a less invasive option. 

Our specialists at Triborough GI will consider factors such as your cancer risk, comorbidities, and any symptoms you may have before recommending the most appropriate screening or test for you. For more information, contact one of our four area offices – in Brooklyn (718) 795-2734, the Bronx (718) 360-1632, Staten Island (718) 710-4906, or Bushwick, NY (718) 865-3960.

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