Background: Improvement in adenoma detection rate (ADR) reduces colorectal cancer incidence by increasing the colonoscopy quality. Using dynamic patient position changes during the withdrawal phase has shown promise in increasing ADR. We conducted this study to assess the effectiveness of the supine position on the improvement of ADR to improve its feasibility and avoid frequent patient position changes, particularly in sedated patients.Methods: This was a randomized, single-blind, parallel-group, single-center study implemented in the Mehregan private in Babol. Inclusion criteria were 40 to 85 years old, 4 L application of polyethylene glycol from the day before the procedure, no history of inflammatory bowel disease, bowel surgery, musculoskeletal problems, and negative familial history of colorectal cancer. Patients were allocated in a 1:1 ratio to the supine or left lateral positions during the withdrawal phase. All colonoscopies were performed by a single physician using a Fujifilm colonoscope. A P-value of <0.005 was considered statistically significant.Results: A total of 880 patients were assessed for eligibility, of which 472 patients were included in the final analysis; 53.4% were female, the mean age of participants was 55.86±10.30 years old, 95.1% of patients had adequate bowel preparation, and adenomatous polyps were the most common histopathologic type (63.7%). Despite the intervention group’s higher rate of ADR and PDR (19.5% vs. 17.7% for ADR and 27.2% vs. 26.5% for PDR), no statistically significant difference in ADR or PDR was detected (P=0.613 and 0.866). Conclusion: No statistical significance was observed despite the increase in ADR when the supine position was used exclusively during the withdrawal phase. As a result, we recommend that the dynamic position change method be used if a position change is required. Nonetheless, additional research is required to determine a more effective alternative to dynamic position change in obese or heavily sedated patients.Trial registration: IRCTID: IRCT20110721007080N5, registration date: 04/05/2020

Background Cap polyposis (CP) is a benign, non-malignant inflammatory disease that affects the rectum. It usually occurs during the 5th decade of life, but children could also be affected. Its specific pathology is unknown. Due to the clinical, endoscopic, and histologic similarities with other disorders such as inflammatory bowel disease, a thorough histologic evaluation is critical to avoid unnecessary interventions. This study presents a 15-year-old child with a previously reported case of solitary rectal ulcer (SRU) that developed into CP determined by colonoscopy and histologic findings. Case presentation A 15-year-old boy who was previously diagnosed with SRU presented to our office with rectal bleeding, mucoid discharge, and abdominal pain. Additional colonoscopy evaluation revealed multiple polyposes varying in size and shape limited to the rectum. Histologic examination revealed a characteristic cap of granulation tissue covering tortuous nondysplastic crypts in the inflamed stroma, indicating that SRU had transformed into CP. Based on the assessments, we planned to perform endoscopic mucosal resection of the lesions in multiple sessions. Conclusions Despite the rarity of CP, the transformation from SRU may be one of its etiologies. Thus, thorough serial histologic evaluation is critical in children with rectal bleeding to avoid unnecessary or harmful interventions.