To evaluate the effectiveness and safety of ultrasound-guided transplanted liver biopsy in children.

We conducted a retrospective analysis of all children who underwent ultrasound-guided transplanted liver biopsy at Beijing Friendship Hospital Affiliated to Capital Medical University between January 2018 and December 2020. Clinical history, laboratory findings, biopsy records, complications, and pathological outcomes were recorded. The χ² test/Mann-Whitney U test was used to compare the differences in age, sex, the number of needle passes, and values of laboratory examination (including platelets, prothrombin activity, etc.) among the children with complications and those without to figure out the statistically significant factors between the two groups.

A total of 180 biopsies were obtained, including 176 biopsies of transplanted liver and 4 biopsies of both transplanted liver and native liver. All the children were successfully punctured, and the diagnostic yield was 95.7% (176/184). No major complications occurred, and the rate of minor complications was 8.9% (16/180). A comparative analysis was performed between children with complications (16 biopsies) and those without (164 biopsies) in terms of the basic conditions, the number of needle passes, and laboratory findings. It was found that children with complications were younger [3.0 (0.9, 15.0) years old vs 5.0 (0.40, 16.0) years old, Z=-2.892, P=0.004], and had worse liver function [aspertate aminotransferase: 62.8 (22.70, 659.00) U/L vs 40.60 (12.70, 446.20) U/L, Z=-3.211, P=0.001; total bilirubin: 9.74 (3.59, 43.46) μmol/L vs 9.45 (2.42, 751.00) μmol/L, Z=-2.007, P=0.045], lower platelet count [213.00 (58.00, 337.00)×10⁹/L vs 233.00 (46.00, 490.00)×10⁹/L, Z=-3.960, P＜0.001], and lower prothrombin activity [82.30 (58.00, 103.00)% vs 85.00 (58.00, 132.10)%, Z=-2.906, P=0.004]. However, sex and the number of needle passes did not affect the occurrence of complications (P＞0.05 for both).

Ultrasound-guided liver biopsy is a reliable and safe method with a high diagnostic yield and low complication rate. Younger age, poor liver function, and lower platelet count and prothrombin activity are risk factors for post-biopsy bleeding in children.