When to Remove Left-Sided Colorectal Polyps? 'Get Them When You See Them'

David A. Johnson, MD


February 20, 2020

This transcript has been edited for clarity.

Hello. This is Dr David Johnson, professor of medicine and chief of gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia.

Colonoscopy and polypectomy are a major part of what we do as gastroenterologists. Many of us have probably been frustrated by discovering a polyp during the insertion phase of colonoscopy, then spending an inordinate amount of time trying to find it again during the withdrawal phase. This is particularly true in the left colon, where we may find ourselves saying, "I know it's there somewhere, because we saw it on the way in."

A Promising Technique

Previous studies on performing polypectomy during insertion have not really shown it to be that beneficial. However, a recently published randomized controlled trial adds important new evidence by describing a technique using carbon dioxide (CO2) gas insufflation and cold snare polypectomy upon initial discovery on insertion.

This technique is associated with potential advantages. First, studies have shown that cold snare polypectomy is approximately 1.5 to 3 times faster than hot snare cautery polypectomy. Second, the use of CO2 avoids some of the overdistention of the colon that we worry about when performing polypectomy, which requires taking a little bit longer on our colonoscopy inspection.

In this study from Japan, 20 experienced endoscopists from seven institutional centers prospectively randomly assigned 220 patients with at least one left-sided polyp <10 mm detected unintentionally upon endoscope insertion. The polyps were either removed right away upon insertion, or the endoscope was inserted to the cecum and removal was attempted subsequently upon withdrawal.

Investigators reported that procedural times actually didn't differ as they relate to time to the cecum, which is somewhat surprising. However, the mean total procedure time was significantly shorter in the group undergoing polypectomy on discovery, by about 3.5 minutes (18.9 minutes vs 22.3 minutes; P < .001).

They also reported that polyps were well hidden in the group assigned to have polypectomy upon withdrawal. Of 107 polyps discovered during insertion in this group, approximately 45% required reinsertion of the colonoscope to identify again, and 6.5% were lost and never discovered again after an average of 3 minutes spent in reinvestigation.

The authors noted that the differing presentation of the colon during insertion and withdrawal may account for these missed polyps. We foreshorten the colon by pulling the colonoscope back. During that process, we actually steepen the angle of some of the colonic folds. It may be more difficult to see some of these as we come back in and efface those folds fully. There is also a lack of reliable identifiers in the left colon, unlike in the right colon, where the distance from the cecum can act as an accurate landmark.

Clinical Applications

I recommend you review the findings from this very important study.

Consider using this technique of removing left colon polyps upon discovery on insertion using cold snare polypectomy and CO2, particularly for smaller lesions (ie, 6-9 mm). I always use cold snare in these patients. The very rare exception is for polyps that may be in the 10 o'clock position, in which it is difficult to rotate the colonoscope around. Maybe use a cold biopsy technique in that one. But, generally, the snare technique is used for polyps 3 mm or greater.

I never use a cold snare technique in pedunculated lesions, which prototype as having a single feeding vessel. In pedunculated lesions, you can still stay with the snare polypectomy and cautery.

When I use the cold snare polypectomy technique, I employ a suction and guillotine approach. I pull the cold snare back into the channel and then have the assistant cut, so that the suction takes it back. If that doesn't work and the suction gets somewhat clogged, I recommend using the trick of taking the valve off the colonoscope and putting your finger over the open port. It gets more direct suction and that will sometimes help get the polyp delivered back in, so as to keep you from wasting a lot of time.

In conclusion, grab these polyps when you see them on insertion, particularly in the left colon, and use cold snare polypectomy with CO2. By doing so, I think you'll find your colonoscopy time is dramatically improved and your frustration is considerably less.

I hope this helps in your practice.

I'm Dr David Johnson, and I look forward to chatting with you again soon.

David A. Johnson, MD, a regular contributor to Medscape, is professor of medicine and chief of gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia, and a past president of the American College of Gastroenterology. His primary focus is the clinical practice of gastroenterology. He has published extensively in the internal medicine/gastroenterology literature, with principal research interests in esophageal and colon disease, and more recently in sleep and microbiome effects on gastrointestinal health and disease.

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