A Big Step Forward for Removing Small Colon Lesions: Embracing the Cold Snare Polypectomy Revolution

David A. Johnson, MD


March 29, 2019

This transcript has been edited for clarity.

I'm David Johnson, professor of medicine and chief of gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia. Welcome back to another GI Common Concerns.

As gastroenterologists, we often encounter and resect colon polyps, particularly those that are relatively small. High-level detectors have shown that approximately 80% of these polyps are 1-5 mm and more than 90% are less than 1 cm.[1] Although ensuring the adequate resection of these polyps is imperative, recent evaluations[2] have shown that there is considerable variation in resection success rates. This leads me to a couple of recent papers[3,4,5] from two of the grandmasters of colonoscopy, Dr Doug Rex and Dr Jerry Waye, whose pearls of advice I would like to pass along here.

The Cold Snare Revolution

Approximately a third of interval cancers are notable at the site of previous polypectomy.[2] If we inadequately resect a diminutive (< 6 mm) or small (6-9 mm) polyp, and then ask patients to wait 5 or 10 years before reexamination, we may be leaving them at a significant risk, despite the initial size of the polyp.

When it comes to strategies for resecting small polyps, Dr Rex has coined the term "the cold revolution," which I think is very accurate. We recognize that the evils of colonoscopy/polypectomy are really predicated on cautery and its associated risk for delayed hemorrhage. Cautery can lead to delayed thermal injury to the deeper tissue, with eschar release in 10-14 days that may lead to the development of an ulceration, potentially exposing a deeper blood vessel, which can cause significant bleeding. However, with cold snare resection, you run only a mild risk of immediate bleeding, particularly with these smaller lesions that have very small blood vessels, if any. We're very adept at dealing with acute bleeding if we see it; and bleeding from most of these small polyps, in particular ones removed with cold snare, are very easily recognized. They just trickle for a bit and then stop. Even in patients who are on antiplatelet agents, these tend not to be a concern and can be dealt with immediately if necessary.

Cold snare entails a standard snare resection, with an adequate resection margin typically being 2-3 mm on either side of the polyp. Cold snare polypectomy has become the standard of care, at least among the European Society of Gastrointestinal Endoscopy, which recently updated its guidelines to suggest that polyps that were < 1 cm should be removed using this technique.[6] I think that experts in the United States would agree with this as well.

Large polyps may be a little bit of a different story, but certainly these smaller lesions (≤ 1 cm) can almost always be removed by cold snare.

I like to use a dedicated cold snare because they're stiffer, braided, and the tissue capture is better. These are useful advantages because, again, adequate resection is really the key.

Tips for Performing Cold Snare

Many people fear cold snare resection because they're concerned about losing the tissue. A great tip that Dr Rex taught me many years ago was to employ a cut-and-suck technique, which works very well. Using that technique, you grab the polyp, pull it back up to the biopsy channel, and tell your technician to cut. It's virtually always a resection recovery at this point and it's something that's very easy to perform and master.

Sometimes when you perform these cold snares, you'll see a small white cord at the base of these polyps. That's a submucosal fibrosis and sometimes a little bit of muscularis mucosa. You do not need to rebiopsy or go back and cauterize it; this is not a neoplastic-type situation. But you should be on the lookout for that little white cord, as you'll see it not infrequently, particularly when you start taking bigger pieces of polyp or a larger polyp (eg, ≥ 10 mm) with a cold snare technique.

The cold snare technique recovery is fairly easy with this cut-and-suck technique, and Dr Waye had a couple of really masterful points that I've applied in my own practice. He recommends that when you see a diminutive polyp on insertion, just grab it with a snare and take it out at that time. The same approach is recommended for these smaller polyps; if it's in a good position, then take it out on the way in. It requires much less time than on the way out, when potentially you're trying to reclaim where you were and maybe are under a little bit of a fecal pool. So remember, grab them while you can.

It's also important to recognize that we do best when operating in the 5-o'clock position. There are rare circumstances where you can't twist and axially rotate the scope to get it in the 5-o'clock position, where a polyp resection by a cold biopsy technique is okay. For 1-2 mm polyps in particular, if you can't rotate the scope, I find that operating in the 10-o'clock position and grabbing it with the biopsy may be a lot easier.

Do not try and piecemeal a polyp with a cold biopsy technique. This is against the current standard of care with these techniques. You may find that you want to lift these polyps if you're in a particular position whereby you cannot get a good grab on them. Here, you can use a little saline, indigo carmine, or methylene blue, which will highlight the margins for you and get a better lift for resection.

Tips for Retrieval

When it comes to retrieval, Dr Waye makes a couple of other very nice points. Sometimes you get that polyp stick on the end of your biopsy and just can't get it in. There are a couple of tricks to consider here. One is to take the trumpet off on your biopsy and use your finger to provide better suction. Sometimes you may consider taking the cap off the biopsy port itself, which will provide a little air leak to augment your suction. Those easy tricks should get that thing to fall right into the trap.

Dr Waye also had useful tips for what happens when you lose a polyp during resection. What do you do then? First, you must locate it, in particular by looking for it under the biopsy cap, in the trumpet, and at the end of the scope. The other trick is to flush in a little water. If you see the water flush down in front of the colonoscope, it means that you're downstream. You'll need to go back upstream, following the flow of the water to that first pool, which is where gravity has taken the polyp. On the other hand, if you flush the water in and see it coming back at your lens, it means the water is flowing up because you're at the top. Here you will need to withdraw the scope and go to the distal pool, which may be the most likely place to suction up the polyp.

Pearls to Keep in Mind

These experts give us several pearls to keep in mind. The cold snare technique is really the way to go for these smaller polyps. There is no role for using piecemeal cold biopsy for attempted removal nor hot biopsy, with the exception of using the avulsion technique during endoscopic mucosa resection, which is beyond the scope of this discussion. And when it comes to retrieval techniques, consider those simple tips for optimizing polyp removal. By applying these lessons, I think you'll see an improvement in your in your speed, efficiency, and rate of success when it comes to small polyp resection.

I'm Dr David Johnson. Thanks again for listening.

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