The risk of colorectal cancer (CRC) is increased in patients having ulcerative colitis (UC). Patients with long-standing extensive colitis, concomitant primary sclerosing cholangitis, or previous history of dysplasia carry an exceptionally high risk of CRC and require regular and short-interval surveillance colonoscopy. Recent guidelines recommend surveillance colonoscopy based on target biopsy rather than random biopsy applying chromoendoscopy (CE) or narrow band image (NBI) technique in UC at risk for CRC. However, the diagnostic yield of NBI-based surveillance and CE-based surveillance is not extensively investigated in the high-risk UC population. The investigators aimed to compare the dysplasia detection rate of NBI with that of CE in UC patients with a high risk of CRC by performing a multicenter, randomized controlled trial.

Inclusion Criteria:

• At least one of the followings should be satisfied;

  1. A patient having extensive ulcerative colitis with 8-year or longer disease duration
  2. A patient having both ulcerative colitis and primary sclerosing colitis
  3. A patient having a previous history of dysplasia at the colitic segment within recent 5 years

Exclusion Criteria:

• All of the following conditions should be excluded for 1st surveillance colonoscopy study

  1. A patient who underwent total or segment colectomy.
  2. A patient who taking (warfarin or direct oral anticoagulants and cannot stop them for procedures owing to the high thromboembolic risk
  3. A patient who has known thrombocytopenia (less than 80,000/µL in recent 6 months
  4. A patient who has a coagulopathy
  5. A patient who has chronic renal disease evidenced by serum creatinine > 1.2 mg/dL within 6 months of study participation
  6. A patient who has already undergone surveillance colonoscopy within 1 year

• All of the following conditions should be excluded for 2nd surveillance colonoscopy study even if they were included in 1st surveillance study.

  1. A patient who underwent total or segment colectomy after 1st surveillance colonoscopy for this trial.
  2. A patient who taking (warfarin or direct oral anticoagulants and cannot stop them for procedures owing to the high thromboembolic risk
  3. A patient who has known thrombocytopenia (less than 80,000/µL in recent 6 months
  4. A patient who has a coagulopathy
  5. A patient who has chronic renal disease evidenced by serum creatinine > 1.2 mg/dL within 6 months of study participation