Polypectomy

Polypectomy principles

The three most important questions to be asked about a polyp are 1. Does it need to be removed? 2. Should I remove it? and 3. Can I remove it? The answer to these questions will differ from one endoscopist to another and from one polyp to another. If the answers are “Yes”, “Yes”, and “Yes” the fourth question is How do I remove it? These questions are the topic of this presentation.

It could be argued that anyone who does a colonoscopy should be able to remove the polyps that they will encounter. What is the sense of putting the patient through a bowel prep, the sedation or anesthesia, only to defer polypectomy and commit the patient to another prep and another sedation? The sense to this situation lies in the polyp where removal is predictably difficult or dangerous. It makes less sense for an inexperienced polypectomist to “have a go” than for them to refer the patient to a more experienced and more expert practitioner. In medicine, discretion is always the better part of valor, and nobody can be blamed for a discretionary referral.

Question 1. Does this polyp need to be removed?

The indications for polypectomy include prevention of colorectal cancer, treatment of symptoms, and assessment of the stability of the colorectal epithelium.

Therapeutic polypectomy is uncommon as polyps rarely cause symptoms. Adenomas usually don’t bleed but inflammatory polyps, which are basically polypoid mounds of granulations, are fragile. Multiple polyps can cause diarrhea and abdominal pain, while large pedunculated polyps can sometimes cause colonic intussusception. So symptomatic polyps are removed to resolve symptoms.

Prophylactic polypectomy is focused on adenomas and sessile serrated lesions, as these are the common benign precursors of carcinoma. There has been some debate about the need to remove all adenomas or just high-risk adenomas, based on the zero increased cancer risk associated with diminutive (<5mm) adenomas. However, all adenomas are generally removed, partly because some diminutive adenomas can be high risk, the total number of adenomas is important in determining cancer risk, setting surveillance intervals, and possibly diagnosing polyposis, and, more selfishly, ensuring that adenoma detection rate statistics are as high as they can be. A policy of removing all adenomas begs the question of how well endoscopists distinguish adenomas from serrated polyps. Most of the work done on this topic shows approximately 60% accuracy overall. The second most common polyp found in the large intestine is the hyperplastic polyp, typically a small, sessile, pale lesion mostly fin the rectum or sigmoid. While these lesions are associated with colorectal cancer in a broad sense (they have KRAS mutations, and when there are >20 they fulfil the criteria for serrated polyposis) they are individually benign. The crypt pattern is very regular, and they do not look like adenomas. I usually sample one or two just to reassure myself that my endoscopic diagnosis is accurate. However in patients with Lynch Syndrome I remove absolutely every mucosal excrescence.

One of the results of polypectomy over time is to allow an evaluation of the stability of the colorectal epithelium. Adenomas are histologic and physical evidence of tumorigenic changes in the molecular pathways controlling colonocyte division, growth, and death. Advanced adenomas represent more advanced molecular tumorigenesis, and multiple adenomas indicate multiple areas of genetic instability. This is why 3 or more adenomas is associated with an increased risk of metachronous adenomas, and 10 or more adenomas is an indication for genetic testing of the germline to rule out polyposis syndromes. Unless all the adenomas are removed the true stability of the epithelium is not appreciated and follow-up is less accurate.

Question 2. Should I remove this polyp?

Not all polyps should be removed at the time they are seen. The first consideration is the indication for the colonoscopy and the circumstances of the examination. If the colonoscopy is done for constipation, and if the preparation is poor, do not try to snare a polyp. The consequences of perforation could be dire. If the patient has severe comorbidities and the polyp is clearly benign and non-threatening, the patient can keep the polyp. The second consideration is the polyp itself. If there is a small chance that you can remove it is better to leave it alone (tattoo it) and refer the patient to a more expert therapeutic colonoscopist. Attempted polypectomy that results in partial polypectomy makes later attempts at complete polypectomy more difficult due to the scarring that the first attempt created. It is also better not to attack polyps that may be malignant. Malignant polyps are in general irregular, hard, and fixed, and attempts at endoscopic removal are unwise. I have never been a fan of determining the nature of a polyp by pit pattern. I find that relying on the gross characteristics as listed above is accurate enough. If there is doubt, biopsy and tattoo.

Question 3. Can I remove this polyp?

My philosophy about polypectomy is to “give it a go”. This is based on the admittedly presumptuous assumption that if I cannot do it, then nobody can do it, and in many cases, the patient will need surgery. This philosophy is also reflective of my type of practice which includes referrals of patients from other endoscopists, other surgeons, or self-referral from the patients themselves. However not every endoscopist can remove large, awkwardly placed lesions. Feeling that removal of such polyps is beyond you is not a weakness, but you benefit the patient by referring them to a more expert person.

Question 4. How do I remove this polyp?

The tools available for polypectomy include cold and hot biopsy forceps, cold and hot snares, endoscopic mucosal resection (EMR) that involves lifting the polyp on a bed of fluid, and endoscopic submucosal dissection (ESD), where fluid is injected into the submucosa and the polyp is dissected off using a combination of needle knife and snare. I have zero experience with EMR and ESD and cannot comment on the techniques. I would only say that in 32 years of removing polyps I have never needed to inject fluid to raise a lesion. Very occasionally I have injected fluid to bring a polyp on the reverse side of a fold forward so that I can snare it.

Cold biopsy: I use jumbo sized forceps for most diminutive lesions. For the large lesions (4 to 5 mm) I apply the forceps to the base, like chopping down a tree. With two bites of the accurately placed forceps the entire polyp falls off. There are almost never any complications.

Hot biopsy: Although I used hot biopsy forceps for diminutive lesions early on in my career I stopped because of concerns over perforation. The coagulation produced by hot biopsy forceps goes down into the colon wall as opposed to a hot snare, where the coagulation is tangential. The advantage of hot biopsy is that the margins of the polypectomy are coagulated so that theoretically there is less chance of residual polyp. The technique I prefer is to use coagulating current (set at 25) intermittently, giving a series of “zaps” rather than one long burst. This allows the heat to dissipate between “zaps”. In addition, a narrow bite on the tissue creates more heat that a wide bite.

Hot biopsy forceps are useful for completely flat lesions, or for small areas of adenoma that remain after snare of a larger sessile polyp. It is possible to control flat adenomas with coagulation, although it may take more than one procedure. Finally, hot biopsy forceps can be an addendum to snare polypectomy, allowing increased control over the edges of the polypectomy.

Cold snare: There seems to be an increase in the popularity of cold snare polypectomy for mid-sized polyps, based upon reduced complications of the polypectomy. However, there is quite often some bleeding after cold snare polypectomy, and for sessile polyps the margin status may be suspect. I prefer hot snare for most polyps over 5mm in size.

Hot snare: The hot snare has been my weapon of choice over a career that has marked the end of the line for thousands of polyps. A technique using the settings of 0 cutting current and 25 coagulation has been effective and safe. As with hot biopsy, intermittent application of the cautery is key. For large sessile polyps the maximum amount contained in the snare is 2cm per “bite”. Starting at one edge of the polyp it is often possible to achieve a plane that facilitates removal of the rest of the lesion. The edema caused by one snare application makes adjacent tissue more prominent. Pushing down on the tip of the snare and aspirating air as the snare closes encourages the lesion to enter the snare. This is easiest when the polyp is located at 6 o’clock. Snaring with a retroflexed scope is tricky initially because scope controls are reversed. To advance the scope you pull back; to withdraw you push in. Take your time with large polyps and don’t hesitate to move the patient so that fluid changes positions and the approach to the lesion itself changes. Control bleeding as it occurs and keep aspirating and irrigating. It is tempting to forget about the patient while your attention is fully focused on the polyp, but this is a mistake.

Removal of the specimen is important so that pathology can be accurately matched with lesion. Large soft lesions (like sessile serrated lesions) pass readily through the scope with aspiration, but pedunculated polyps over 10mm diameter may get stuck. Large polyps may need to be cut into smaller pieces with the snare; this is an annoying and time consuming process but it is worth it to get the histology.

Suspicious polyps and any polyps > 2cm need to have their site marked with a tattoo, so that the polypectomy site can be checked or even resected. Currently I use SPOT and find a redundant fold adjacent to the polypectomy site. It generally only takes 1 to 2 ml of solution to raise a bleb.

There is no real disadvantage to piecemeal polypectomy; at least not enough to make me learn how to do ESD and EMR.

Complications of Polypectomy

There are three significant complications of endoscopic polypectomy in the large intestine. These are hemorrhage, perforation, and post polypectomy syndrome.

Hemorrhage

Significant bleeding after polypectomy can occur during the procedure or afterwards. The range of bleeding rates varies between 2% to 6%, depending on the proportion of polyps in the more dangerous right colon, the size of the polyps and the experience of the polypectomist. Immediate bleeding can be controlled by a combination of adrenalin (1:10,000) injection, re snaring the stalk, clipping the bleeding artery, or cautery with hot biopsy or Argon Plasma Coagulation. It can be a little scary to see blood pulsing from a wound in the colon, especially when the blood obscures the source. Adrenalin injection is the best choice when the exact bleeding point is not obvious, and clips are good for precise treatment.

Post procedure bleeding can begin any time after the polypectomy for up to 2 weeks. The larger the polyp the higher the risk and right sided polyps are more likely to bleed than left sided. I advise patients about the risks before the procedure and then again afterwards. I recommend against going on trips away from medical help for 2 weeks after the procedure, recommend taking life easy and avoiding anticoagulants and hypertension.

Prevention of post-polypectomy bleeding with prophylactic clips is easy with pedunculated polyps and makes sense with large sessile lesions if the snare has gone into the submucosa and the wound is suitable for a clip. Prophylactic adrenalin injection makes less sense as it wears off fairly quickly.

Treatment of post-polypectomy bleeding depends on the circumstance. The bleeding is usually arterial and starts suddenly and painlessly. The patient feels the need to defecate but the output is bloody. A large artery will keep bleeding and the patient may lose enough blood to faint. A smaller artery may well stop on its own after a variable length of time with a variable amount of blood loss. Assess the patient for anemia, shock, and check vital signs. Resuscitate as necessary with IV fluids. Ask about anticoagulants and check clotting studies. Treat abnormalities. If the bleeding is continuing an immediate colonoscopy can be performed, irrigating clots and reaching the presumed site of bleeding. If the bleeding has died down and the patient is stable they may take a prep and then be rescoped.

The colon may contain dark blood and clots, but the main clue to the site of bleeding is bright red, fresh blood. The actual site of bleeding may be covered in adherent clot, which encourages constant seepage. The clot must be removed, using forceps or a snare if necessary. The bleeding may be an obvious spurting vessel which can be clipped or injected. If the vessel is in the base of a wide wound clips are hard to apply and heat can be used with an argon plasma coagulator.

I make a point of never snaring multiple large polyps in more than one part of the colon because this makes finding the site of bleeding more difficult. A patient with multiple large polyps will need a close follow up soon anyway.

Post-polypectomy perforation

Rates of post polypectomy perforation vary between studies depending on the site of the polyp, the size of the polyp, the technique used for polypectomy, and the experience of the polypectomist. The range is 0.5% to 2%.

A perforation occurs during polypectomy because full thickness coagulation damages the full thickness of the bowel wall, or because removal of the polyp creates an instant hole. In the first case the necrosis can take a day or two to slough by which time the inflammation has caused adhesions that can seal the gradually developing hole. A full seal leads to post polypectomy syndrome, with localized pain and tenderness but no free air. Antibiotics are usually given until symptoms settle. A partial seal leads to a late perforation which may be more symptomatic because patients have usually eaten and there is stool in the colon. Peritonism and a lack of response to antibiotics are indications for surgery.

In the second case there is immediate pneumoperitoneum with pain. Depending upon the likely size of the hole conservative therapy may be tried because the colon is still well prepared, and contamination of the peritoneal cavity is minimal. Surgery to repair the hole is usually laparoscopic and the defect can often be directly repaired. Use of endoscopic clips to close a defect is sometimes done using carbon dioxide as an insufflating agent. This may make the pneumoperitoneum worse before it gets better.

Prevention of perforation:

Perforation rarely follows snare of a pedunculated polyp. Keep the snare within 5mm of the polyp, use intermittent coagulation and be liberal in the use of clips. Sometimes the assistant transects the stalk before you are ready to coagulate so use a clip to seal the stalk. Thick stalks tend to have larger arteries and should be transected slowly and clipped before the snare is even used.

Sessile polyps should be taken in 2cm chunks. The right colon has a thinner wall than the left and tends to form large sessile or villous adenomas and low profile sessile serrated lesions. Intermittent coagulation set at 25 is important. Prophylactic use of clips in right sided polyps is reasonable.