Colonoscopy Practice and Quality: Colonoscopy Practice and Quality: Special Patients

0:00Welcome to Board Pearls. This is episode five of five, the last episode of the Colonoscopy Practice and Quality chapter, in the Endoscopic Procedures module. This episode is colonoscopy adapted to the patient. The first patient is a man on dialysis who takes apixaban, and his case shows which preparation is safe on dialysis and which two aren't, when his procedure should be scheduled, and how his anticoagulant is planned around a polypectomy. The second patient is a woman with cirrhosis, and her case shows what's different at the rectum, why her international normalized ratio, INR, shouldn't decide transfusion, and how her sedation changes. A pregnant woman with a severe colitis flare shows when colonoscopy goes ahead in pregnancy and how it's done. And a man with a recent coronary stent shows when a colonoscopy should wait.

0:49Here's the first patient. A fifty-eight-year-old man has end-stage kidney disease on hemodialysis on Mondays, Wednesdays, and Fridays. He has atrial fibrillation treated with apixaban, and iron deficiency anemia with a normal esophagogastroduodenoscopy. He's booked for colonoscopy, and his referral notes he may need a polypectomy.

1:11His kidney failure and his anticoagulant make him a special population for colonoscopy. Special populations change all four phases of the procedure, preparation, sedation, intervention, and recovery, and in each case the underlying physiology decides which standard step has to change. For him, that physiology is his vulnerability to fluid and electrolyte shifts and his altered drug clearance.

1:35His preparation is chosen first, because the wrong one can injure what kidney function he has left and disturb his electrolytes. Polyethylene glycol electrolyte solution is preferred over phosphate-based preparations, because sodium phosphate causes acute phosphate nephropathy and is contraindicated in chronic kidney disease, hypertension, diuretic or angiotensin-converting enzyme inhibitor use, and older patients, as episode one covers. Magnesium-based preparations, magnesium citrate and sodium picosulfate with magnesium oxide and citric acid, need caution in advanced kidney disease, because magnesium is retained. So he gets polyethylene glycol. In the man with stage three kidney disease in episode one, the concern was mainly phosphate. On dialysis, his kidneys can't clear magnesium either, and the non-absorbed, electrolyte-balanced preparation asks the least of them.

2:30His dialysis schedule sets the timing. Hyperkalemia during preparation is a risk in dialysis patients, so the procedure is timed around dialysis, ideally the morning after a session, so that any electrolyte shifts during preparation can be corrected. With Monday, Wednesday, and Friday dialysis, his colonoscopy is booked for a Tuesday or Thursday morning. A Monday morning booking, after the long weekend gap, would put his preparation at the point in his week when his potassium and fluid are most likely to be off.

3:01His apixaban needs a plan before the day, because his kidney failure changes how anticoagulants clear. Direct oral anticoagulant clearance is altered in kidney disease. Apixaban is the most renally tolerated direct oral anticoagulant, while rivaroxaban and edoxaban have reduced clearance in advanced chronic kidney disease. Dabigatran is about eighty percent cleared by the kidneys, so its hold lengthens as creatinine clearance falls. The procedure's bleeding risk sets the hold. Diagnostic colonoscopy with cold biopsy is a low bleeding-risk procedure that allows aspirin and most antithrombotics to continue. Polypectomy of larger polyps, ampullectomy, endoscopic mucosal resection, EMR, endoscopic submucosal dissection, and percutaneous gastrostomy placement are high-risk procedures, and they require holding antiplatelet or anticoagulant drugs on the standard schedule, with bridging only in selected patients at high thromboembolic risk. For apixaban, that's twenty-four to forty-eight hours before a low-risk procedure and forty-eight to seventy-two hours before a high-risk one. Warfarin reversal needs its own plan in a patient with a mechanical valve or a recent thrombotic event.

4:13His hold is planned from the procedure he's expected to need, because deciding on the morning, after a large polyp is found, is too late. His referral anticipates polypectomy, and his iron deficiency makes a significant lesion possible, so his apixaban is held as for a high-risk procedure, forty-eight to seventy-two hours, with his kidney function in mind. A purely diagnostic examination with cold biopsies would have let him continue it. His Thursday colonoscopy, with a preparation scoring three in every segment, finds a fifteen-millimeter ascending colon adenoma, which is removed by EMR in the same session because his apixaban was already held. A single adenoma of ten millimeters or more puts his next colonoscopy at three years, as episode three covers. His defect, after a lesion under twenty millimeters, isn't one where prophylactic clip closure has shown benefit, as episode four covers. He restarts apixaban one to three days after the procedure, once hemostasis is secure.

5:11The second patient's risks come from her liver rather than her kidneys. A sixty-one-year-old woman has alcohol-related cirrhosis, Child-Pugh B, with portal hypertension, and needs colonoscopy after a positive fecal immunochemical test. Her INR is one point eight and her platelets are sixty-two thousand.

5:30Her cirrhosis changes her colonoscopy in three intersecting ways: varices, coagulation, and sedation. Portal hypertension can produce rectal varices that bleed with instrumentation, so any therapeutic intervention near her rectum calls for caution, and a polyp next to rectal varices isn't snared the way it would be in another patient. Her rectum is inspected carefully on entry and on withdrawal.

5:54Her INR and platelet count look alarming, but they overstate her bleeding risk. Coagulation in cirrhosis is rebalanced rather than uniformly anticoagulated, because the liver makes fewer anticoagulant proteins, such as protein C, protein S, and antithrombin, alongside fewer clotting factors, and the INR measures only the clotting factors. So her INR and platelet count overestimate her bleeding risk. Thresholds for platelets and plasma before high-risk procedures follow cirrhosis-specific and American Society for Gastrointestinal Endoscopy periprocedural guidance, not population norms. For a high-risk procedure, viscoelastic testing would identify the dominant defect, with fibrinogen or platelets corrected only when they're truly low. Transfusing plasma to normalize her INR would treat a number, and in cirrhosis the extra volume raises portal pressure, the opposite of what her rectal varices need. A diagnostic colonoscopy needs none of it.

6:52Her sedation changes because her liver clears drugs poorly. Fentanyl is preferred over morphine, because it depends less on hepatic metabolism and has no active metabolites to accumulate in encephalopathy. Longer-acting agents accumulate, so short-acting benzodiazepines or propofol with anesthesia involvement are preferred, and propofol is the better choice, because benzodiazepines can precipitate hepatic encephalopathy. Her colonoscopy goes ahead without plasma, under propofol with anesthesia, with careful rectal inspection.

7:26Pregnancy changes colonoscopy most of all, because a second patient is exposed. A twenty-nine-year-old woman with ulcerative colitis is pregnant and has a severe flare that needs tissue diagnosis to guide treatment. Elective colonoscopy is deferred whenever possible in pregnancy, because the procedure exposes the fetus to maternal sedation, abdominal pressure, and the small radiation dose of any fluoroscopy. When colonoscopy is necessary, for acute lower gastrointestinal bleeding with hemodynamic compromise, suspected obstruction, or a severe inflammatory bowel disease flare needing tissue, as in her case, it goes ahead. The second trimester is preferred, because organogenesis is complete and the uterus isn't yet large enough to compromise her positioning and venous return.

8:10Her trimester also changes the drugs and the position. Midazolam and other benzodiazepines are avoided in the first trimester because of theoretical teratogenicity, and propofol with anesthesia involvement is preferred when deeper sedation is needed. Left lateral positioning keeps the uterus from compressing the aorta and vena cava. If she's at eleven weeks, her urgent indication still proceeds, without midazolam. At twenty weeks she's in the preferred window. Either way, she lies tilted to the left. Procedures in pregnancy by trimester are covered in chapter thirty-five.

8:43A recent coronary stent changes not how colonoscopy is done but whether it happens now. A sixty-six-year-old man had a drug-eluting coronary stent placed four months ago, is on dual antiplatelet therapy, and needs an elective polypectomy. His elective procedure is deferred until his antiplatelet therapy can be safely de-escalated, rather than attempting polypectomy on full dual therapy, because stent thrombosis is far deadlier than procedural bleeding. Elective procedures are deferred for thirty days after a bare metal stent and six months after a drug-eluting stent, so his polypectomy waits two more months. Active bleeding would change that urgency.

9:22Each population changes one or two steps of the procedure for a specific reason. Kidney disease changes the preparation, the timing, and drug clearance. Cirrhosis changes caution at the rectum, the transfusion thresholds, and the sedation. Pregnancy changes the timing, the drugs, and the position. And a fresh stent changes whether the procedure happens now.

9:45Here are the traps the boards set in these patients. Sodium phosphate preparations are never given in kidney disease. Magnesium-based preparations need caution in advanced kidney disease. A dialysis patient's colonoscopy is scheduled the morning after a session. Direct oral anticoagulant clearance changes in kidney disease, and apixaban is the most renally tolerated. A high-risk procedure that's anticipated gets its anticoagulant hold planned in advance. A polyp near rectal varices calls for caution. A cirrhotic patient isn't transfused by INR alone. Morphine and long-acting sedatives are avoided in cirrhosis. An elective colonoscopy in pregnancy that can wait does wait, and midazolam is avoided in the first trimester. And an elective polypectomy isn't attempted on full dual antiplatelet therapy within six months of a drug-eluting stent.

10:38So, start to finish. Adjust colonoscopy to the patient's physiology. In kidney disease, use polyethylene glycol, avoid sodium phosphate, use magnesium preparations with caution, schedule dialysis patients the morning after a session, and remember that apixaban is the most renally tolerated direct oral anticoagulant, held forty-eight to seventy-two hours before a high-risk procedure.

11:02In cirrhosis, look for rectal varices, don't transfuse by INR alone, and prefer fentanyl with propofol or short-acting agents. In pregnancy, defer elective examinations, and when one is needed, prefer the second trimester, left lateral tilt, and propofol, with no midazolam early. On antithrombotics, hold by procedure risk, and defer elective polypectomy for six months after a drug-eluting stent.

11:28That completes chapter thirty. Chapter thirty-one is GI emergencies.

11:33For the full chapter, the practice vignettes, and the topic-tagged question bank, head to board pearls dot com. You'll find the rest of the series on Apple Podcasts, Spotify, or wherever you listen to podcasts. That brings us to the end of episode five of five of chapter thirty, and I'll see you in the next one.