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colonoscopy

A procedure for viewing the entire length of the colon to the ileocecal valve. Viewing the distal ileum may be indicated if enteritis is suspected. Indications: 1) rectal bleeding 2) unexplained abdominal symptoms 3) equivocal or abnormal barium enema 4) removal or search of polyps (see intestinal polypectomy) 5) search for & biopsy of suspected carcinoma 6) follow-up for colorectal cancer or adenomatous polyp(s) 7) intraoperative colonoscopy 8) unexplained weight loss 9) metastatic carcinoma of unknown primary 10) unexplained chronic diarrhea 11) unexplained iron-deficiency anemia - serum ferritin < 100 mg/mL suggested as indicator [11] 12) screening for colorectal carcinoma - 10 year interval sufficient [25] - reduces risk of colorectal cancer by 18% but does not reduce 10 year cancer-related deaths [54] - extension of 10-year screening intervals may be warranted, especially for female & younger patients [55] 13) surveillance Contraindications: 1) patient refusal 2) patient is dying or at the point of death (moribund) 3) known or suspected perforation 4) unavailability of resuscitation 5) unstable cardiac condition 6) respiratory insufficiency 7) elderly > 75 years with limited life expectancy [56] Clinical significance: - Sensitivity: - 89% for polyps > 5 mm in size [3] - may miss 2-4% of colon cancers [5] - better in the left colon than in the right [21] - colonoscopy might not provide any substantial protection in the right colon [21] - Screening: - reduction in mortality? - 57% reduction in colon cancer deaths [6] - absolute 10 year risk reduction for normal colonoscopy at 56 years of age = 0.1% [47] - no reduction in 10 year colorectal cancer mortality or all-cause mortality [53] - 56% risk reduction for right-sided colon cancer [23] - 84% risk reduction for left-sided colon cancer [23] - colorectal cancer found in 0.5% of colonoscopies - high-risk adenomas found in 3.2% of colonoscopies - reduction in colorectal cancer within 10 years 0.98% vs 1.20% [53] - surveillance - colorectal cancer detection at surveillance colonoscopy rare among older adults regardless of prior adenoma finding [57] - advanced neoplasia detection was more common in elderly with prior advanced adenoma vs nonadvanced adenoma Procedure: Patient preparation: 1) informed consent 2) five days prior to procedure - avoid nuts, iron - walking aids bowel preparation - see perioperative antiplatelet therapy - see perioperative anticoagularion 3) one day prior to procedure* a) clear liquids with no red or orange gelatin b) metoclopramide 10 mg at 11 AM & 3 PM c) Colyte 4 liters (2 glasses every 30 min) beginning at 1 PM d) evening/morning split dose sodium phosphate - two 45 mL bottles given 6, 12 or 24 hours apart outperforms Colyte [12] e) Kaiser Permanente uses 240 g of Gavilyte (maybe twice) 4) procedure preparation a) intravenous access b) cardiac rhythm monitor c) pulse oximetry d) O2 if indicated e) resuscitation equipment f) left lateral position with right knee flexed more than left 5) inadequate bowel preparation should be followed by repeat colonoscopy - exception: mass lesions including colonic polyps >= 5 mm can be excluded, despite the indadequate preparation [20] * see bowel preparation for colonoscopy or flexible sigmoidoscopy Sedation: 1) adequate sedation is achieved when the patient develops slurred speech 2) pharmacologic agents a) intravenous benzodiazepine & opioid combination (standard) b) meperidine (Demerol) 50-100 mg IV c) midazolam (Versed) 0.5 mg increments d) morphine 5-10 mg IV e) diazepam (Valium) 5-20 mg IV f) fentanyl (Sublimaze) 0.05-0.1 mg IV 3) sedation reversal a) should be available b) naloxone (Narcan) 0.4 mg IV up to 2 mg c) flumazenil (Mazicon, Romazicon) - 0.2 mg IV over 15 seconds every min up to 1 mg Technique: 1) retroflexion may be useful for polypectomy 2) narrow-band imaging & chromoendoscopy are techniques used to identify polyp characteristics (pit morphology) [14] 3) policy of at least 7 minutes examining the colonic mucosa during colonoscopy withdrawal (guideline) has no effect on polyp yield [18] 4) apparently, 2 pairs of eyes better than 1 - nurse paired with gastroenterologist viewing colon detect 28% more adenomas than gastroenterologist alone [27] 5) endocuff-assisted colonoscopy improves cecal intubation rate & may improve adenoma detection [36] 6) repeat examination of the right colon during colonoscopy with higher colorectal adenoma detection rate 27% than single pass 22% [50] 7) adenoma detection rate may be an emerging quality measure [42] - gastroenterologists detect more adenomas than other endoscopists [51] Complications: 1) bacteremia, hemorrhage, colonic perforation, serosal tears, abdominal distension, vasovagal reflex, splenic avulsion, cardiac arrhythmias, volvulus, toxic megacolon, pneumoperitoneum 2) significant complications: 5/1000 [10] to 2.5/1000 [27] a) perforation: 1/2500 [2]; 1/1000 [6]; 0.07% [16];1/1200 [17]; 1/10,000 [41]*; 3/100,000 (without intervention) 6/100,000 with intervention [44]; 5.8/10,000 unrelated to polypectomy[48]; 0/12,000 [53] - gastrointestinal bleeding & perforation observed/expected ratios > 1 at all ages within 0-60 days of colonoscopy [52] - diverticulosis, inflammatory bowel disease, glucocorticoid use, certain comorbid conditions increases risk [48] - provider factors (experience, volume, performance by non-gastroenterologist influences risk [48] b) post-polypectomy serosal burns 0.02% [41] c) bleeding - major bleeding 14/12,000 [53] - bleeding due to polypectomy (0.14%) [41]; 2.4/1000 [48] - polyp size risk factor [48] - bleeding requiring hospitalization 1/600 [17] d) complications resulting in emergency department visit: 1% [22] e) death: 1/55,000 [2]; 1/20,000 [6]; 1/14,000 [17]; 3/100,000 [48] 3) risk factors for complications - older age, male, polypectomy, low-volume endoscopist [17] - history of stroke, COPD, atrial fibrillation, or congestive heart failure [35] 4) other - myocardial infarctions & ischemic stroke predominated over intestinal perforation in elderly > 75 years [52] - cardiovascular & pulmonary complications related to sedation [26] - postpolypectomy electrocoagulation syndrome (0.003-1%) [26,48] - gas explosion [26] - injury to spleen (rare, but likely under-reported) [48] * study [41] reports unsually low rate of complications & unsually high rate of pathologic findings (no discussion regarding financial implications for GI endoscopists) Management: 1) antithrombotics/anticoagulants/antiplatelet agents a) in general, stop most antithrombotics before a colonoscopy due to increased risk of bleeding with polypectomy 1] aspirin is an exception, continue aspirin in most cases 2] stop warfarin, clopidogreal 5 days prior to the procedure 3] stop dabigatran, rivaroxaban, apixaban 1-2 days prior to the procedure 4] if risk of procedure is high, bridge warfarin with LMW heparin b) if polypectomy is not performed, restart antithrombotics immediately following the procedure. c) if polypectomy is performed 1] restart warfarin about 12 hours after the procedure 2] restart dabigatran, rivaroxaban, apixaban about 48-72 hours after the procedure 3] restart clopidogrel 24 hours after the procedure [30] 2) Post-procedure: a) observe patient until fully awake b) instruct patient to notify physician for: 1] fever/chills 2] abdominal pain 3) risk of colon cancer diminished after negative colonoscopy [9] - absolute 10 year risk reduction for normal colonoscopy at 56 years of age = 0.1% [47] 4) afternoon colonoscopies have higher failure rates than morning colonoscopies [13] 5) risk factors for new (within 6-36 months) or missed cancers [15] - older age - diverticular disease - large serrated polyps (adenomatous polyps) [19] - right-sided or transverse colon cancers - advanced adenomas may be associated with risk colon cancer - nonadvanced adenomas may not be associated with risk [45] - inadequate training or experience (colonoscopy by internist or family practice) - inadequate facilities (office-based rather than hospital-based) 6) repeat colonoscopy may detect source of obscure bleed [20] Notes: - repeat colonoscopies common among Medicare patients without clear indication [24] - ~ 25% of colonoscopies in elderly may be inappropriate [28,46] - complication rate is much higher in patients > 90 years of age than in patients 75-79 years of age (9.2% vs. 0.7%), mostly due to cardiopulmonary events [38] - colon cancer is much more frequent in patients > 90 (14% vs. 2%) (%s for patients with indications for colonoscopy, not screening) [38] - even in Veterans Administration surveillance colonoscopy is overused [37] - 3-fold increased risk of early/missed colon cancer in patients with inflammatory bowel disease [29] - 5.8-6.8% in patients without inflammatory bowel disease - 15.1-16.5% in patients with Crohn disease - 15.8-18.8% in patients with ulcerative colitis [29] - patients generally know whether their colonoscopy found polyps but do not know the characteristics of the polyps [31] - higher adenoma detection rates linked to lower colorectal cancer risk [34] - older black persons more likely than older whites for colorectal cancer diagnosis within 5 years after colonoscopy (7.1% vs 5.8%) [43]

Related

adenocarcinoma of the colon &/or rectum bowel preparation (whole bowel irrigation, bowel evacuation) colonoscope flexible sigmoidoscopy intestinal polypectomy screening for colon cancer virtual (CT) colonoscopy (CT colonography)

Specific

colonoscopy through stoma colonoscopy with cautery colonoscopy with dilation of stricture colonoscopy with polypectomy colonoscopy with removal of foreign body fluorescence-guided colonoscopy

General

gastrointestinal endoscopy

References

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