Polypectomy is an obvious reason for colonoscopy: finding the little devils that can morph into something cancerous and cutting them out before they begin their deadly invasion. Standard operating procedure for many endoscopy pros is to mark polyps on the way to the cecum and then remove them on the way out. Traditionally, that’s how it’s been done.
There’s just one problem: Polyps can hide.
Finding a previously noted polyp during scope removal is often easier said than done. Precious minutes can be wasted doing a search, or the polyp may not be found at all. Reasons include small polyp size and cold-snare removal, according to Komeda, et al., who wrote, “It was difficult to retrieve small, sessile, and proximal colon polyps.”
Teramoto, et al., performed a multicenter randomized controlled trial (also known as the PRESECT study). They discovered that performing polypectomy during insertion “significantly shortens the total procedure time and eliminates all missed polyps without experiencing any disadvantages.”
In another randomized controlled trial, Wildi, et al., evaluated polypectomy on insertion and withdrawal for 301 patients. While all polyps detected on insertion and withdrawal were easily removed at the time they were found, 7.3% of polyps slated to be removed on withdrawal only were subsequently not found. The authors wrote, “Removal of polyps ≤ 10 mm during withdrawal only is associated with a considerable polyp miss rate. We therefore recommend that these polyps are removed during both insertion and withdrawal.”
Conversely, a 2021 systematic review and meta-analysis concluded that there were “no obvious advantages” to polypectomy during both insertion and withdrawal phases. And Moons, et al., stated that “maneuvers can be applied during insertion and withdrawal of the colonoscope to optimize mucosal visualization and decrease the number of missed polyps.”
Gweon, et al., conducted a randomized trial at three university hospitals. “For patients in the study group,” they wrote, “polypectomy was performed together with careful inspection during both colonoscope insertion and withdrawal. In the control group, polyps were inspected and removed only during colonoscope withdrawal. The primary endpoint was the ADR [adenoma detection rate], which was defined as the percentage of patients with ≥ 1 adenoma.” What they found was that the ADR was similar in both groups, with a polyp miss rate of 2.1 percent in the control group.
Their conclusion? Paying attention pays off. “Polypectomy and careful inspection during both colonoscope insertion and withdrawal did not improve the overall ADR compared with standard colonoscopy.”
Bleeding is often a factor during polypectomy. Janik found that cold-snare polypectomy (CSP) results in less bleeding than hot-snare polypectomy (cautery), making CSP safer. Katagiri, et al., conducted a single-center, prospective, randomized controlled trial, examining whether epinephrine-added saline could influence resection time. What they found was that out of 261 lesions, epinephrine “shortened the time for resection by shortening the time to cessation of immediate bleeding compared with conventional CSP in colorectal polyps ≤ 10 mm.”
Another factor in accurate polypectomy is the utilization of water and/or gas—generally carbon dioxide—to expand the colon so clinicians can more readily analyze the mucosa during withdrawal. Unusual anatomical structures can present problems in this regard: redundant colons, which present with excessive looping, and colons with severe angulation, generally on the left side, can make examination challenging.
Commonly used techniques to cope with this challenge include water immersion (WI) and water exchange (WE). In both techniques, water is infused into the colon while inserting the colonoscope to the cecum. During WE, the water is aspirated during insertion, while during WI the water is aspirated during removal. Both are effective when paired with gas.
Joseph Anderson outlined a third technique, total underwater colonoscopy, that can be especially helpful in colonoscopy for those with anatomical challenges. “Water can distend the colon so that it is actually narrower and shorter than when gas insufflation is used,” he wrote. “In addition, water has the advantage of weighing down the sigmoid, especially in the left lateral decubitus position, allowing for a straighter and less redundant sigmoid.”
Anderson added that he uses this technique when he encounters “frequent looping that does not respond to abdominal pressure, colonoscope stiffening, or change in position.” Shutting off the air and infusing water allows him to complete the insertion.
Water acts as a lubricant, Anderson wrote, and has the added benefit of not causing spasms as air does. When working with a patient who has a severely angulated sigmoid colon, a clinician might be tempted to pump air into the lumen to help facilitate visualization. Anderson wrote that “water can distend the colon, allowing for visualization of the lumen without maximally distending the lumen similar to air, which can exacerbate the angulation.” Another benefit to water is it can help prevent baro-trauma to the cecum.
A side benefit to water, Anderson noted, is that it helps patient comfort. “Meta-analyses have shown that patients who have unsedated or minimally sedated examinations with water experienced less pain, required less sedation, and were more likely to have examinations that were complete than those who had the colonoscopies performed with air.”
When he’s performing unsedated or minimally sedated exams, he observed, “I routinely use water immersion beginning at insertion with the air valve turned off. I find this particularly useful in older, thinner patients, especially women. In addition, in patients with multiple comorbidities, cecal intubation often can be achieved safely with minimal sedation.”
Another benefit is thatwater can help aid in adenoma detection, although some clinicians may argue the point. “Because water does not fully distend the lumen, flat polyps may be easier to detect because they may not completely flatten as compared to the use of gas for insufflation,” Anderson wrote.
Where water could become a real asset is in endoscopic mucosal resection (EMR). Because polyps have more of a tendency to float in water, they may be easier to see. They also tend to “float into the snare,” according to Anderson. “Polyps also are more likely to appear protruding underwater, as opposed to flat with gas insufflation. Because water has a magnifying property, UEMR may allow for easier delineation of the polyp’s border, also facilitating complete removal. Underwater may be safer than traditional EMR using air because the lumen may not be as distended and therefore the colonic wall may not be as thin as when gas is used.”
But underwater colonoscopy isn’t all perfection. The use of water can lengthen the procedure time—particularly on insertion. And while water can (obviously) improve bowel prep, it can cause a whitish mucus that’s difficult to remove. There’s some question as to the physiological effects of a large amount of water introduced into the colon, but Anderson cited two studies indicating no safety issues with the process. “Water infusion does not appear to alter serum electrolytes or vital signs.”
Polypectomy Best Practices
According to the American Gastroenterological Association, the AGA “Clinical Practice Update on Appropriate and Tailored Polypectomy: Expert Review” was published to give “timely guidance on a topic of high clinical importance to the AGA membership.” Its best-practices recommendations start simply: “A structured visual assessment using high-definition white light and/or electronic chromoendoscopy and with photodocumentation should be conducted for all polyps found during routine colonoscopy.” And of course, polyps should be inspected closely for evidence of submucosal cancer.
The next recommendation is to use cold-snare polypectomy for small polyps (less than 10 millimeters in size). If polyps are truly tiny (1–3 millimeters), cold-forceps polypectomy is an acceptable alternative. The authors do not recommend using hot-forceps polypectomy.
For intermediate-sized polyps, AGA authors expect that clinicians are “familiar with various techniques, such as cold-and hot-snare polypectomy and endoscopic mucosal resection, to ensure effective, safe, and optimal resection.” In addition, they advise using lifting agents or underwater endoscopic mucosal resection (EMR) to remove intermediate sessile polyps.
Serrated polyps need cold-resection techniques, and for polyps with difficult margins, submucosal injection is recommended.
The authors recommend hot-snare polypectomy for pedunculated lesions larger than 10 millimeters. Practitioners should have a full understanding of “the endoscopy suite’s electrosurgical generator settings appropriate for polypectomy or postpolypectomy thermal techniques.” The AGA advises against using clips to close holes for polyp sites smaller than 20 millimeters. And if the polyp is 20 millimeters or larger, is recurrent at the site, or has a challenging location for polypectomy, refer to an endoscopy center.
Lesions such as these that may require referral should be tattooed for future placement. “Tattoos should be placed in a location that will not interfere with subsequent attempts at endoscopic resection,” they wrote.
And if you’re seeing clear evidence of submucosally invasive cancer in a nonpedunculated polyp, the AGA recommends an immediate referral for surgical evaluation.
Make a Hole
Endoscopic mucosal resection, or EMR, has become an effective tool for removing larger colonic polyps, obviating the need for traditional surgery. EMR is popular because of its higher efficacy and patient-satisfaction rates, quicker recovery, lower costs and complication rates, and “the ability to preserve normal gut function,” according to the Mayo Clinic.
But removing large polyps is challenging at best. Practitioners often inject a 0.9% sodium chloride solution, enhanced with dye, to help elevate the polyp and make removal easier by creating a cushion between the mucosal layer and muscular layer. This helps prevent thermal injury and lowers perforation risk. But saline is rapidly absorbed into the body, which means practitioners often must inject more solution to finish the procedure.
To deal with this challenge, GI professionals have long come up with other “homemade” solutions to help elevate polyps. Ultimately this led to the development of FDA-approved gels and other submucosal injection agents. One of the most popular, SIC-8000, was approved in 2015 as a Class 2 medical device, and other gels quickly followed— notably, without much clinical data—and hit the market. ORISE was particularly well received as it was a darker color than SIC-8000—especially beneficial during EMR.
However, problems quickly arose with its use.
Esnakula, et al., wrote in a case report, “ORISE Gel may potentially hinder the histologic evaluation of mucin-predominant lesions such as mucinous adenocarcinoma or adenocarcinoma with mucinous component. Hence, the gastroenterologist needs to report the use of ORISE Gel on the requisition form or endoscopic report. In addition, pathologists must be aware of the histologic appearance of ORISE and be prepared to use additional stains to prevent overinterpretation of such findings in the ER specimen.”
It gets worse. Mendelson, et al., examined how lifting agents can present as a colonic mass that mimics cancer. “Lifting agent granulomas have become a routine endoscopic technique to help achieve full resection of flat/sessile colorectal polyps and early-stage cancers,” they wrote. “This report confirms that these granulomas exhibit colonic transmural involvement. Sub-serosal blood vessel involvement is reported for the first time. It is important to recognize the unique characteristics of these new synthetic lifting agents. Their propensity to develop a mass-forming granulomatous reaction has the potential to mimic invasive adenocarcinoma clinically, radiologically and pathologically. This can significantly impact patient care and management both clinically and surgically.”
And in a 2023 editorial, Rex and Lahr detailed numerous clinically significant adverse issues with ORISE. They wrote, “ORISE appeared to persist in the tissue, and biopsies from specimens taken at a later date showed an eosinophilic material accompanied by a multi-nucleated giant cell reaction.”
“Purported advantages of submucosal injection before resection have sparse evidential backing,” Nett and Binmoeller wrote. “Poorly performed submucosal injection can make EMR more challenging and may increase the risk of certain complications.”
But EMR is where underwater colonoscopy can really shine. “Compared with reported outcomes of conventional EMR, underwater EMR achieves high rates of en-bloc resection and low rates of lesion recurrence,” they wrote.
Anderson cited a randomized trial showing the effectiveness of underwater EMR for smaller polyps. “Applying the technique to smaller lesions may be a good starting point for endoscopists who want to try UEMR,” he wrote.
Closing the Hole
Clinicians have several tools in the kit when it comes to fixing the gap created by a polypectomy. In an ideal world, the gap would close itself and everyone would go home happy. But in the real world, practitioners often use clips, sutures or staples to bring the edges together again.
But what happens when the polyp is irregular, the hole large, or the spot in question difficult to reach?
A novel through-the-scope suturing system was put through its paces in a 2021 multicenter study. Eight medical centers located in the United States examined the system’s feasibility and safety, as well as secondary considerations such as “assessment of need for additional closure devices, prolonged procedure time, and technical feasibility of performing the procedure with an alternative device(s).”
The authors concluded that the device was safe, efficient and worked as intended to close large and irregular defects that were difficult or impossible with established devices.
A multicohort retrospective study by Bi, et al., examined the rate of delayed bleeding with a through-the-scope suturing device (TTSS). The authors found that “TTSS alone or with TTSCs was effective in achieving complete closure of all post-EMR defects, despite a large lesion size. After TTSS closure with or without adjunctive devices, delayed bleeding was seen in 3.2% of cases.”
While polyps and their malignant offspring continue to present challenges to GI professionals, innovation and substantive research help make the job easier and more rewarding, improving the surgical experience and patient care.
