The Pulse | Friday, July 19, 2019
Colon Polypectomy Techniques: The Nitty Gritty
As a gastroenterologist, it is important to be competent in removing most colon polyps that are encountered, since this capability is part of being a high quality endoscopist. In this day and age, polypectomy techniques are enhanced by high resolution colonoscopes, chromoendoscopy, narrow band imaging, lifting agents, clips, caps, various snares and Argon Plasma Coagulation (APC). Polyp removal can also be performed using Cold Endoscopic Mucosal Resection (EMR), underwater EMR without submucosal injection, full thickness resection and Endoscopic Submucosal Dissection (ESD).
An increased focus in quality measures contributes to high quality colonoscopy, which includes the Adenoma Detection Rate (ADR) of 20% in women and 30% in men, a 95% cecal intubation rate and a cecal withdrawal time of at least six minutes (which should not include the time taken for polypectomies). ADR may be enhanced in the future using Artificial Intelligence (AI).
Small sessile, pedunculated and semi-pedunculated polyps are commonly removed using a standard snare. However, large pedunculated or semi-pedunculated polyps are at increased risk for post-polypectomy bleeding since they are often arterial in origin. Given this risk, other techniques will need to be performed prior to snare polypectomy, which includes placing a hemoclip or Endo-loop at the base of the stalk and/or injection with Epinephrine 1:10,000.
Serrated adenomatous polyps are particularly challenging and their incidence is increasing, namely due to high resolution endoscopes. They are particularly dangerous because of their obscurity, leading to colon cancer if missed. They are mostly in the right colon, very flat, often moderate to large in size and may be obscured by the presence of overlying mucus. Moderate to large serrated adenomas are often removed by EMR using the lift-cushion method with Eleview, Methylene blue or Indigo Carmine combined with saline or Hespan. Submucosal injection of Eleview and Hespan can provide a polyp cushion duration of about 30-60 minutes, whereas saline will flatten out after several minutes. The serrated adenoma can then be removed in one piece or by piecemeal technique using a braided snare. Non-braided snares will slide off flat serrated adenomas, making it difficult to grasp the polyp. Ablation of the periphery of the polypectomy site with Argon Plasma Coagulation (APC) to destroy any residual polyp is then performed. The polypectomy site can be closed with clips (see image below). In general, clips are not necessary for polyps less than 20 millimeters unless the patient is on antiplatelet or anticoagulation therapy, but even the data on the latter is weak.
A few points that are important to note is that Methylene Blue and Indigo Carmine will help highlight the peripheral edge of the polyp. They are superior to using SPOT or India Ink, since these agents do not cause submucosal scarring in case a partial polypectomy is performed when a polyp is large or if polyp recurrence occurs. Partially removed polyps are generally removed within three to six months. One can be generous when using normal saline to lift a serrated flat polyp, and 5-20 milliliters may be needed depending on polyp size. Note that a non-lifting sign may imply that there may be an underlying malignancy and that a surgical resection may be required. Also note that SPOT or India Ink should not be injected beyond the muscularis mucosa, especially if surgical intervention is contemplated, since these agents may confuse the surgeon regarding polyp location if injected into the peritoneal cavity.
Post-polypectomy bleeding is managed endoscopically by: 1) tamponade using dilute epinephrine, 2) mechanical hemostasis using clips, 3) thermal hemostasis using snare tip soft coagulation, bipolar therapy, coagulation forceps or APC and 4) spray hemostasis.
This short review on colon polypectomy techniques should help the GI procedure nurse and GI tech understand the nuances and challenges associated with flat serrated polyps, moderate to large pedunculated or semi-pedunculated polyps and intricacies with the methods used to remove them safely and effectively with the lowest morbidity.
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