The Effectiveness of Right- vs Left-lateral Starting Position in Unsedated Diagnostic Colonoscopy with Modified-water Immersion Method: A Randomized Controlled Trial Study

OBJECTIVE: A colonoscopy study in sedated patients with air insufflation showed that right-lateral starting position (RLP) improved abdominal discomfort and reduced cecal intubation time. The aim of this study was to determine if RLP vs left-lateral starting position (LLP) may produce similar results in unsedated patients examined with a modified-water immersion (m-WI) method. METHODS: Consecutive patients for diagnostic colonoscopy meeting the inclusion criteria were randomized. Patients and colonoscopist were unblinded. The m-WI method entailed suction during insertion not only for fecal debris evacuation but also to facilitate passage through difficult or angulated colonic flexures. Water was infused as needed when any difficulty was encountered during insertion. A bowel visualization scale (BVS) (0=totally blurred visualization; 1=blurred lumen visualization; 2=small fecal debris with clear mucosa visualization; 3= clear visualization) was used to evaluate the interference of fecal debris with cecal intubation rate and time. RESULTS: A total of 142 patients (72 in RLP and 70 in LLP) were enrolled. The respective pain score, visual analog scale, (VAS) and cecal intubation rate were not significantly different. The cecal intubation time was nearly significantly different (13.4±4.5 min vs 11.7±5.4 min; p=0.054) and was significantly different in the constipation subgroup (16.0±3.5 min vs 8.6±3.8 min; p=0.001). The cecal intubation time based on BVS showed significant difference between RLP and LLP in Scale 2 (13.9±4.6 min vs 10.3±4.2 min; p=0.003) and Scale 2 and 3 combined (13.2±4.3 min vs 10.6±4.8 min; p=0.01), respectively. CONCLUSION: RLP did not improve the pain score, and LLP showed better performance in unsedated m-WI colonoscopy patients (ClinicalTrial.gov, NCT03489824).