Body size and restricted papillary exposure during pediatric ERCP with standard duodenoscopes: a retrospective cohort study

Background Endoscopic retrograde cholangiopancreatography (ERCP) is used for biliary and pancreatic disorders in children, usually with standard therapeutic duodenoscopes. We examined whether body size was associated with papilla–scope apposition and whether apposition co-occurred with technical constraints or altered cannulation performance. Methods We retrospectively reviewed all consecutive ERCP procedures performed in patients younger than 18 years at Wuhan Children’s Hospital between October 2020 and April 2026. Papilla–scope apposition was graded intra-procedurally as none, mild, moderate, or severe according to the visible space between the distal duodenoscope tip and the major papilla. The primary analysis included the first biliary-primary ERCP for each child. Body size and apposition were assessed using Spearman rank correlation. Working-space limitation and scope instability were compared by apposition status, and biliary cannulation outcomes were examined exploratorily. Results The cohort comprised 117 children undergoing 134 ERCP procedures; deep selective cannulation succeeded in 129/134 (96.3%). Eighty-three procedures were biliary-primary and arose from 82 children. In the primary analysis (n = 82), apposition was absent in 49 procedures, mild in 14, moderate in 9, and severe in 10. Median body weight decreased from 30.0 kg with no apposition to 11.0 kg with severe apposition, and weight was inversely associated with apposition grade (ρ = −0.825, P < 0.001). Limited working space occurred in 84.8% of procedures with apposition versus 4.1% without apposition (P < 0.001), and scope instability in 51.5% versus 18.4% (P = 0.003). Median cannulation time was 64 s with none/mild apposition and 121.5 s with moderate/severe apposition (P = 0.115). Cannulation time > 300 s or failed cannulation occurred in 20.6% and 36.8%, respectively (OR 2.24, 95% CI 0.74–6.84; P = 0.221). Conclusions Smaller body size was associated with greater papilla–scope apposition during pediatric biliary ERCP using standard duodenoscopes. Apposition was closely associated with limited working space and more frequent scope instability, while its relationship with cannulation performance remained uncertain.