Colonoscopy

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Contents 1 More Specific Terms 2 Introduction 3 Indications 4 Contraindications 5 Clinical-significance 6 Procedure 7 Complications 8 Management 9 Notes 10 More General Terms 11 Additional Terms 12 References

More Specific Terms

• virtual (CT) colonoscopy (CT colonography)

Introduction

• 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

• rectal bleeding
• unexplained abdominal symptoms
• equivocal or abnormal barium enema
• removal or search of polyps (see intestinal polypectomy)
• search for & biopsy of suspected carcinoma
• follow-up for colorectal cancer or adenomatous polyp(s)
• intraoperative colonoscopy
• unexplained weight loss
• metastatic carcinoma of unknown primary
• unexplained chronic diarrhea
• unexplained iron-deficiency anemia

• serum ferritin < 100 mg/mL suggested as indicator [11]

• screening for colorectal carcinoma

• 10 year interval sufficient [25]

Contraindications

• patient refusal
• patient is dying or at the point of death ( moribund)
• known or suspected perforation
• unavailability of resuscitation
• unstable cardiac condition
• respiratory insufficiency

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:

• 57% reduction in colon cancer deaths [6]
• 56% risk reduction for right-sided colon cancer [23]
• 84% risk reduction for left-sided colon cancer [23]

Procedure

• Patient preparation:

• informed consent
• one day prior to procedure*

• clear liquids with no red or orange gelatin
• metoclopramide 10 mg at 11 AM & 3 PM
• Colyte 4 liters (2 glasses every 30 min) beginning at 1 PM
• evening/morning split dose sodium phosphate - two 45 mL bottles given 6, 12 or 24 hours apart outperforms Colyte [12]

• procedure preparation

• intravenous access
• cardiac rhythm monitor
• pulse oximetry
• O2 if indicated
• resuscitation equipment
• left lateral position with right knee flexed more than left

• walking aids bowel preparation
  

• * see bowel preparation for colonoscopy or flexible sigmoidoscopy
  
• Sedation:

• adequate sedation is achieved when the patient develops slurred speech
• pharmacologic agents

• intravenous benzodiazepine & opioid combination (standard)
• meperidine ( Demerol) 50-100 mg IV
• midazolam ( Versed) 0.5 mg increments
• morphine 5-10 mg IV
• diazepam ( Valium) 5-20 mg IV
• fentanyl ( Sublimaze) 0.05-0.1 mg IV

• sedation reversal

• should be available
• naloxone ( Narcan) 0.4 mg IV up to 2 mg
• flumazenil ( Mazicon, Romazicon)

• 0.2 mg IV over 15 seconds every min up to 1 mg
  

• Technique:

• retroflexion may be useful for polypectomy
• narrow-band imaging & chromoendoscopy are techniques used to identify polyp characteristics (pit morphology) [14]
• policy of at least 7 minutes examining the colonic mucosa during colonoscopy withdrawal (guideline) has no effect on polyp yield [18]

Complications

• bacteremia, hemorrhage, perforation, serosal tears, abdominal distention, vasovagal reflex, splenic avulsion, cardiac arrhythmias, volvulus
• significant complications: 5/1000 [10] to 1/10,000

• perforation: 1/2500 [2]; 1/1000 [6]; 0.07% [16]; 1/1200 [17]
• bleeding requiring hositalization 1/600 [17]
• complications resulting in emergency department visit: 1% [22]
• death: 1/55,000 [2]; 1/20,000 [6]; 1/14,000 [17]

• risk factors for complications

• older age, male, polypectomy, low-volume endoscopist [17]

Management

• Post-procedure:

• observe patient until fully awake
• instruct patient to notify physician for:

• fever/ chills
• abdominal pain

• risk of colon cancer diminished after negative colonoscopy [9]
• afternoon colonoscopies have higher failure rates than morning colonoscopies [13]
• 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
• inadequate training or experience (colonoscopy by internist or family practice)
• inadequate facilities (office-based rather than hospital-based)

• repeat colonoscopy may detect source of obscure bleed [20]

Notes

• repeat colonoscopies common among Medicare patients without clear indication [24]

More General Terms

• gastrointestinal endoscopy

Additional Terms

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

References

1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 334-36
2. Journal Watch 22(17):137, 2002
   - US Preventive Services Task Force. Screening for colorectal cancer. Recommendation & rationale. Ann Intern Med 137:129, 2003 [1]
   - Pignone M, Rich M, Teutsch SM, Berg AO, Lohr KN. Screening for colorectal cancer in adults at average risk: a summary of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med. 2002 Jul 16;137(2):132-41. Review. Summary for patients in: Ann Intern Med. 2002 Jul 16;137(2):I38. <PubMed> PMID: [2] <Internet> [3]
   - Pignone M, Saha S, Hoerger T, Mandelblatt J. Cost-effectiveness analyses of colorectal cancer screening: a systematic review for the U.S. Preventive Services Task Force. Ann Intern Med. 2002 Jul 16;137(2):96-104. Review. Summary for patients in: Ann Intern Med. 2002 Jul 16;137(2):I38. <PubMed> PMID: [4] <Internet> [5]
3. Journal Watch 24(20):151, 2004 Pickhardt PJ, Nugent PA, Mysliwiec PA, Choi JR, Schindler WR. Location of adenomas missed by optical colonoscopy. Ann Intern Med. 2004 Sep 7;141(5):352-9. PMID: [6]
4. Kim HS, Park DH, Kim JW, Jee MG, Baik SK, Kwon SO, Lee DK. Effectiveness of walking exercise as a bowel preparation for colonoscopy: a randomized controlled trial. Am J Gastroenterol. 2005 Sep;100(9):1964-9. PMID: [7]
5. Internal Medicine News, Dec 1, 2005 quotes Johanson JF, at the annual meeting of the American College of Gastroenterology
6. Taylor, WC Clinician's Corner, Clinical Crossroads, A 71-year old woman contemplating a screening colonoscopy JAMA 2006; 295:1161
7. Singh H et al, Risk of developing colorectal cancer following a negative colonscopy examination: Evidence for a 10-year interval between colonoscopies. JAMA 2006; 295:2566 PMID: [8]
   - Church TR, Screening for colorectal cancer by colonoscopy: Adding to the evidence. JAMA 2006; 295:2411 PMID: [9]
8. Pishvaian AC, Al-Kawas FH. Retroflexion in the colon: a useful and safe technique in the evaluation and resection of sessile polyps during colonoscopy. Am J Gastroenterol. 2006 Jul;101(7):1479-83. PMID: [10]
9. Brenner H et al, Does a negative screening colonoscopy ever need to be repeated? Gut 2006, 55:1145 PMID: [11]
10. Levin TR, Zhao W, Conell C, Seeff LC, Manninen DL, Shapiro JA, Schulman J. Complications of colonoscopy in an integrated health care delivery system. Ann Intern Med. 2006 Dec 19;145(12):880-6. Summary for patients in: Ann Intern Med. 2006 Dec 19;145(12):I39. PMID: [12]
11. Sawhney MS et al, Should patients with anemia and low normal or normal serum ferritin undergo colonoscopy? Am J Gastroenterol 2007, 102:82 PMID: [13]
12. Rostom A et al, A randomized prospective trial comparing different regimens of oral sodium phosphate and polyethylene glycol-based lavage solution in the preparation of patients for colonoscopy. Gastriointest Endosc 2006, 64:544 PMID: [14]
13. Sanake MR et al, Afternoon colonoscopies have higher failure rates than morning colonoscopies. Am J Gastroenterol 2006, 101:2726 PMID: [15]
14. Su M-Y et al, Comparative study of conventional colonoscopy, chromoendoscopy, and narrow-band imaging systems in differential diagnosis of neoplastic and nonneoplastic colonic polyps. Am J Gastroenterol 2006, 101:2711 PMID: [16]
15. Bressler B et al, Rates of new of missed colorectal cancers after colonoscopy and their risk factors: A population-based analysis. Gastroenterology 2007, 132:96 PMID: [17]
16. Iqbal CW et al. Surgical management and outcomes of 165 colonoscopic perforations from a single institution. Arch Surg 2008 Jul; 143:701. PMID: [18]
17. Rabeneck L et al, Bleeding and perforation after outpatient colonoscopy and their risk factors in usual clinical practice. Gastroenterology 2008, 135:1899 PMID: [19]
18. Sawhney MS et al. Effect of institution-wide policy of colonoscopy withdrawal time 7 minutes on polyp detection. Gastroenterology 2008 Dec; 135:1892. PMID: [20]
19. Li D et al. Association of large serrated polyps with synchronous advanced colorectal neoplasia. Am J Gastroenterol 2009 Mar; 104:695. PMID: [21]
20. Medical Knowledge Self Assessment Program (MKSAP) 15, American College of Physicians, Philadelphia 2009
21. Brenner H et al. Protection from right- and left-sided colorectal neoplasms after colonoscopy: Population-based study. J Natl Cancer Inst 2010 Jan 20; 102:89. PMID: [22]
    - Baxter NN and Rabeneck L. Is the effectiveness of colonoscopy "good enough" for population-based screening? J Natl Cancer Inst 2010 Jan 20; 102:70. PMID: [23]
22. Leffler DA et al. The incidence and cost of unexpected hospital use after scheduled outpatient endoscopy. Arch Intern Med 2010 Oct 25; 170:1752. PMID: [24]
23. Brenner H et al Protection From Colorectal Cancer After Colonoscopy: A Population-Based, Case-Control Study Ann Intern Med January 3, 2011 154:22-30 PMID: [25]
    - Weinberg DS Colonoscopy: What Does It Take to Get It 'Right'? Ann Intern Med January 4, 2011 154:68-69 PMID: [26]
24. Goodwin JS et al Overuse of Screening Colonoscopy in the Medicare Population. Arch Intern Med. Published online May 9, 2011 <PubMed> PMID: [27] <Internet> [28]
25. Brenner H et al. Long-term risk of colorectal cancer after negative colonoscopy. J Clin Oncol 2011 Oct 1; 29:3761. PMID: [29]
26. Colonoscopy [30]
27. National Guideline Clearinghouse
    - Sedation and anesthesia in GI endoscopy. American Society for Gastrointestinal Endoscopy ngc-guideline: [31]
    - Colonoscopic surveillance for prevention of colorectal cancer in people with ulcerative colitis, Crohn's disease or adenomas. National Institute for Health and Clinical Excellence ngc-guideline: [32]

colonoscopy