Colon Cancer Screening with Colonoscopy

1. See Also
   1. Colonoscopy Intervals for Colon Cancer Screening
   2. Colon Cancer Risk Factors
2. Efficacy
   1. Identifies up 95% of Colon Cancer
   2. Efficacious and reduces mortality
   3. Preferred over other Colon Cancer screening modalities
   4. Reference
      1. Mandel (1993) N Engl J Med 328:1365-9
      2. Lieberman (2000) N Engl J Med 343:207-8
3. Interpretation: Criteria for a high quality Colonoscopy
   1. Minimal fecal residue following colon preparation
   2. Colonoscopy reaches the cecum
   3. Withdrawal time from cecum to rectum is 6 minutes or more
   4. Complete removal of identified polyps (not piecemeal excision)
   5. Rex (2002) Am J Gastroenterol 97:1296-1308
4. Adverse Effects
   1. Minor common adverse effects
      1. Adverse effects of preparation medications
      2. Adverse effects of Sedation
   2. Serious common adverse effects
      1. Perforations: 1 in 500-3000
         1. Rectosigmoid: 66%
         2. Cecal: 13%
         3. Ascending Colon: 7%
         4. Transverse Colon: 7%
         5. Descending Colon: 7%
      2. Major Bleeding: 1 in 1000
         1. Most common with biopsy or lesion excision
         2. May occur up to 2 weeks after Colonoscopy
   3. Uncommon
      1. Splenic trauma
      2. Vasovagal reaction
      3. Endocarditis
   4. Rare
      1. Sepsis
5. Findings: Polyps
   1. See Colonic Polyps
6. Protocol
   1. See Bowel Preparation
   2. No antibiotic prophylaxis is needed in most cases
      1. Not indicated despite cardiac conditions, prosthetic joints, or vascular grafts
   3. Anticoagulants
      1. Aspirin and NSAIDS may be continued for all endoscopic procedures
      2. Clopidogrel
         1. Low risk of bleeding (e.g. routine Colonoscopy): May continue Clopidogrel
         2. High risk of bleeding
            1. Low risk of thrombosis: Stop Plavix for 7 days
            2. High risk of thrombosis (e.g. drug eluting stent placed in the last year): delay procedure
      3. Warfarin
         1. Low risk of bleeding (e.g. routine Colonoscopy): May continue Warfarin
         2. High risk of bleeding
            1. Low risk of thrombosis: Stop Coumadin for 3-5 days
            2. High risk of thrombosis (e.g. drug eluting stent placed in the last year): Warfarin bridging with Heparin stopped 4-6 hours before procedure
7. Management: Suspected colonoscopic perforation
   1. Indications for immediate laparotomy
      1. Peritoneal signs
      2. Unreliable patient or comorbid conditions
      3. Large defect
      4. Poor Bowel Preparation
   2. Evaluation of stable, reliable patient
      1. Step 1: Obtain upright abdominal XRay
         1. Laparotomy for Free air
      2. Step 2: Obtain CT Abdomen
         1. Laparotomy for large perforation
      3. Step 3: Observe
         1. Indications
            1. Negative upright Abdomen
            2. Negative CT or contained perforation on CT
         2. Conservative protocol
            1. Patient kept NPO on intravenous fluids
            2. Prophylactic antibiotics
            3. Serial exams, XRays, and White Blood Cell count
         3. Laparotomy Indications
            1. Clinical deterioration
            2. Increased White Blood Cell count
8. References
   1. Kavic (2001) Am J Surg 181:319-32