Different bowel preparation schedule leads to different diagnostic yield of proximal and nonpolypoid colorectal neoplasm at screening colonoscopy in average-risk population

Dis Colon Rectum. 2011 Dec;54(12):1570-7. doi: 10.1097/DCR.0b013e318231d667.


Background: Accumulating evidence indicates that the timing of bowel preparation is crucial, but its impact on the diagnostic yield of proximal or nonpolypoid colorectal neoplasm remains unclear.

Objective: This study aimed to investigate the impact of the timing of bowel preparation on the adenoma detection rate for nonpolypoid colorectal neoplasm at colonoscopy.

Design: This study is a retrospective analysis of a screening colonoscopy cohort database.

Setting: The investigation was conducted at a screening colonoscopy unit in an university hospital.

Patients: A consecutive series of 3079 subjects who received primary screening colonoscopy with different timing of bowel preparation was analyzed.

Intervention: Different timing of bowel preparation (same day vs prior day) was studied.

Main outcome measures: The main outcomes measured were patient demographics, timing of bowel preparation, colon-cleansing levels, diagnostic yields of colonoscopy, including adenoma, advanced adenoma, and nonpolypoid colorectal neoplasm.

Results: There were a total of 1552 subjects in the morning group and 1527 in the evening group. More subjects had proximal adenoma (175, 11.3% vs 138, 9.0%, P = .04), advanced adenoma (68, 4.4% vs 46, 13.0%, P = .044), nonpolypoid colorectal neoplasm (98, 6.3% vs 67, 4.4%, P = .018), proximal nonpolypoid colorectal neoplasm (71, 4.6% vs 40, 2.6%, P = .004), and advanced nonpolypoid colorectal neoplasm (25, 1.6% vs 12, 0.8%, P = .036) detected by same-day preparation. On multivariate regression analysis, the adenoma detection rate was significantly higher in the same-day group regarding overall and proximal adenoma (OR 1.23, 95% CI: 1.00-1.50; OR 1.35, 95% CI: 1.05-1.74), advanced adenoma (OR 1.53, 95% CI: 1.04-2.28), overall, proximal, and advanced nonpolypoid colorectal neoplasm (OR 1.48, 95% CI: 1.06-2.08; OR 1.82, 95% CI: 1.20-2.75; OR 1.96, 95% CI: 1.12-3.37). The adenoma detection rate was also significantly different among endoscopists.

Limitation: This was a single-center, nonrandomized trial.

Conclusions: Improving bowel preparation quality by same-day preparation may lead to enhanced detection of overall, proximal, and advanced nonpolypoid colorectal neoplasm.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoma / diagnosis*
  • Adult
  • Cathartics / administration & dosage*
  • Colonoscopy*
  • Colorectal Neoplasms / diagnosis*
  • Drug Administration Schedule
  • Early Detection of Cancer*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Odds Ratio
  • Retrospective Studies
  • Time Factors


  • Cathartics