Normal morphometry of the biliary tree in pediatric and adult populations: A systematic review and meta-analysis

Purpose: This study aimed to characterise the normal morphometry of the biliary tree in pediatric and adult populations, through a systematic review and meta-analysis. Methods: This study, conducted using the PRISMA guidelines and registered with PROSPERO, searched MEDLINE, EMBASE, SCOPUS and Web of Science databases up to October 2022, and updated to August 2023. Studies that reported extractable data on diameter and length of the right, left and common hepatic ducts (LHD, RHD and CHD), and common bile duct (CBD) were included. Quality of the included studies were assessed using the Anatomical Quality Assessment (AQUA) tool. Statistical analysis included subgroup analyses according to sex, age, geographical location, and imaging modality. Results: In total, 60 studies were included, of which 44 studies reported adequate data for meta-analysis on 23,796 subjects. Overall, the pooled mean diameter of the CBD was 4.69 mm (95 % CI: 4.28–5.11). Significant differences were found between pediatric (1.32 mm, 95 % CI: 1.03–1.61) and adult (4.97 mm, 95 % CI: 4.67–5.27) subjects, as well as US (3.82 mm, 95 % CI: 3.15–4.49) and other imaging modalities, including MRI (6.21 mm, 95 % CI: 4.85–7.57) and ERCP (7.24 mm, 95 % CI: 6.08–8.40). The CBD diameter measured significantly larger distally (5.20 mm, 95 % CI: 4.60–5.80) than proximally (4.01 mm, 95 % CI: 3.51–4.51). Conclusions: The results obtained from this evidence-based study may guide the establishment of standardised reference values and ranges of the normal biliary tree in pediatric and adult populations and aid clinical understanding.