Toilet smartphone use, prolonged defecation time, and bowel preparation quality in adults undergoing colonoscopy: a prospective cross-sectional study

Toilet smartphone use has been linked to prolonged defecation, but its association with bowel preparation quality is unclear. We evaluated whether prolonged defecation time, frequent smartphone use during defecation, and problematic smartphone-use tendency were associated with bowel preparation quality and anorectal findings. This prospective cross-sectional study included 879 adults undergoing elective colonoscopy at a tertiary center. Toilet habits, bowel symptoms, and Smartphone Addiction Scale–Short Version (SAS-SV) scores were assessed before colonoscopy. Prolonged defecation time was defined as > 10 min, frequent toilet smartphone use as “often” or “almost always,” and inadequate preparation as Boston Bowel Preparation Scale score < 6. Colonoscopic outcomes were prospectively recorded. Each intercorrelated exposure was examined in a separate logistic regression model adjusted for age, sex, body mass index, smoking, alcohol use, and colonoscopy indication, and additionally for straining, hard stools, and constipation. Absolute prevalences, model-standardized probabilities, Firth penalized regression, and a post hoc adjustment for morning versus afternoon procedure timing were added. Prolonged defecation time and frequent toilet smartphone use were reported by 565 (64.3%) and 340 (38.7%) participants. Inadequate bowel preparation occurred in 209 (23.8%), and hemorrhoids were detected in 315 (35.8%). Inadequate preparation occurred in 2/314 (0.6%) versus 207/565 (36.6%) participants with defecation time ≤ 10 versus > 10 min, and in 27/539 (5.0%) versus 182/340 (53.5%) without versus with frequent smartphone use. In adjusted, exposure-specific models, prolonged defecation time, frequent toilet smartphone use, and each 10-point SAS-SV increase were associated with inadequate preparation (adjusted odds ratios [aORs], 33.36, 13.03, and 2.58; Firth aORs, 26.14, 12.13, and 2.52; all p < 0.001) and with hemorrhoids (aORs, 4.95, 3.69, and 1.19). Estimates were consistent across alternative smartphone-use definitions, and the associations with inadequate preparation were unchanged after adjustment for procedure timing. Prolonged defecation time, frequent toilet smartphone use, and higher problematic smartphone-use tendency were associated with inadequate bowel preparation and hemorrhoids. These cross-sectional associations identify candidate behavioral markers of inadequate bowel preparation that warrant prospective validation; they do not establish directionality or causation.