The Polyp: A Colon's Archrival

Comments
Print

Who's that in the red suit? (And why is he the bad guy?) This is the question the American Cancer Society is posing to the public through their new ad campaign featuring Polyp Man, a pesky character who wanders the streets, dodging healthcare workers and disrupting neighborhoods, in search of a colon to victimize. The ads urge people age 50 and older to be tested for colorectal cancer with the hope of catching a polyp before it becomes cancerous. The slogan for the campaign is, "Get the test. Get the polyp. Get the cure."

Colorectal cancer is the third most common cancer diagnosed in both men and women in America. According to the American Cancer Society, 44 percent of Americans are currently tested for colon cancer, but more than 50 percent of all colon cancer deaths could have been detected from early screening. The good news is, the death rate from colorectal cancer has been decreasing during the past 20 years, likely because of an increase in early detection and improved treatments.

As awareness of polyps and the associated risk of colon cancer continues to grow, nurses working within the endoscopy field will find it more and more necessary to stay abreast of advancements in polypectomy procedures and instrumentation. By continuing to explore these innovations, they can ensure polyp retrieval within their facilities is as safe and simple as possible.

The Procedure

Eric G. Weiss, MD, FACS, FASCRS, of the Department of Colorectal Surgery at Cleveland Clinic Florida in Fort Lauderdale, Fla., points out that there are a variety of instruments available to endoscopy nurses, including biopsy forceps, graspers, baskets and snares, to tackle even the most challenging polyps.

The two primary methods of polyp removal are hot biopsy and snaring. Weiss says hot biopsy is typically preferred when dealing with relatively small polyps, 3 mm or less. The jaws of the forceps, between 1 and 2 mm in size, can open up to about 1 cm wide to encompass a polyp. The endoscopist then applies cautery to ablate the base of the polyp so it can be retrieved and sent to pathology for analysis.

Snaring, which involves lassoing a polyp with a wire loop and shaving it off the bowel wall, is best when removing both sessile polyps (those attached by a large base) and pedunculated polyps (those attached by a stalk).

Destructive techniques such as argon beam coagulation are often reserved for patients who otherwise couldn't tolerate a colonoscopy because of preexisting health conditions, according to Weiss.

Small polyps can often be suctioned through the endoscope's working channel into a trap device attached to the suction tubing, though one drawback of this technique is the possibility of red-outs, or the obstruction of the physician's view by the polyp itself.

Another problem with suctioning is the polyp can become macerated, hindering histopathologic analysis. Naomi L. Nakao, M.D., Diplomat of Internal Medicine in New York, N.Y., points out that by preserving the polyp intact, a clinician can determine the size and type of the polyp, whether or not it has a stalk and, most importantly, whether or not it contains any malignant cells.2

There is some controversy over whether or not small polyps -- less than 1 cm in diameter -- should be removed through colonoscopy. The decision is greatly dependent on the patients age, past history family history and the presence of other diseases.3

The Instruments

When selecting an instrument for polyp retrieval, several factors should be considered, including the size, type and location of the polyp.

Maureen Cain, manager if GI Endoscopy at the Mayo Clinic in Scottsdale, Ariz., says instrument selection depends largely on physician preference. Often the physician will have a select set of instruments with which he or she is comfortable. The Mayo Clinic has a variety of instruments available, including a large snare, a small snare, a rotatable snare and hot biopsy, a regular biopsy and a cautery stick.

Weiss says nurses are often more familiar with instrument options than the doctors themselves.

"Nurses get to work with a lot of doctors and get a feel for different sized polyps and what different people do," he says.

The industry has moved toward disposables as opposed to reusables to address the risk of cross contamination.

During this time, a variety of advancements have been made in polyp retrieval. Manufacturers are continually developing snares in different shapes and sizes to assist the endoscopy staff in retrieving a wide range of polyps. Probably two of the most recent innovations in this arena are the rotatable snare and the Nakao snare.

The rotatable snare can be rotated around the polyp without continually repositioning the patient or the endoscope. Hanson says US Endoscopy's Rotator snare can help reduce procedure time and increase patient comfort. Sarah Robinson, LPN, a GI Technician at the Mayo Clinic in Scottsdale, Ariz., says the rotatable snare can be very helpful when dealing with a polyp in a location that is difficult to reach with other snares.

The Nakao snare, co-developed by Dr. Naomi Nakao and U.S. Endoscopy Group, is a combination snare and retrieval net that allows the polyp to be excised and captured with one instrument. This cuts down on procedure time and allows the physician to preserve the polyp intact. Surgeons opting to use the Nakao snare will need to use an endoscope with a 3.2 channel or larger. Hanson says it appears most colonoscopes made today meet this size requirement.

Weiss says in general it is not the type of snare that is most important, but rather the level of familiarity the person performing the procedure has with the device.

One of the biggest improvements in polyp retrieval, he adds, is in energy delivery systems. Rather than simply delivering a constant voltage of electricity to the polyp site, new technology can actually monitor the amount of current flowing through the tissue and adjust its strength as needed to further reduce the risk of perforation.

Difficult polyps

Small, pedunculated polyps with a stalk are typically the easiest to remove, according to Weiss.

Large, flat polyps, especially those located on folds, present the biggest challenge. Robinson adds that polyps located in areas such as the cecum and the ascending colon also require a special level of care.

Saline-epinephrine injection is one technique that is improving safety in retrieval procedures. A needle is inserted through the colonoscope and used to inject saline, epinephrine, or both at the base of the polyp. This causes the polyp to rise and creates a cushion or gap between the polyp and the bowel wall, decreasing the risk of perforation. The polyp can then be removed with a large snare. Pieces of the polyp remaining along its periphery can be chipped away using a smaller snare.

Jerome D. Waye, in his article, "How to Tackle the Tricky Polyp," states that injecting the base of a large polyp may not be the best removal approach for the reason that it causes the stalk to swell and can make snare placement more difficult.4

He does note, however, that polyps in the right colon, while tricky, will often respond well to saline injection and piecemeal polypectomy.

The "spike" snare is another tool that can assist a physician in retrieval of a more difficult flat polyp. A tiny needle at the tip of the snare latches into the mucosa so the snare does not slip, but instead opens wider as it encompasses the polyp. Hanson says a good "spike" snare will remain latched to the mucosa without causing trauma to the tissue.

A basket, or mesh-covered snare, is a useful tool in retrieving large polyps once they have been removed with a standard snare.

The probability of failing to retrieve a polyp ranges from 2.1 percent to 16.5 percent and is often a result of several factors including loss during aspiration, fragmentation during suctioning and disappearance in a pool of fluid or behind a fold.1

Endoscopic mucosal resection (EMRs) devices, once approved, should offer yet another option in polyp removal, according to Weiss. The device pulls the polyp into a chamber, invaginates the bowel wall, and then uses stapling technology to eliminate the problem, he explains.

There are a large number of variables to consider when performing polypectomy, from the patient's health history to the type of polyp being retrieved.

For a complete list of references log on to www.endonurse.com.

Comments
comments powered by Disqus