Surveillance post image-guided percutaneous liver biopsy in children is variable. The aim of this study was to assess the value of 4-6-h post-procedure ultrasonography (US) in detecting post-liver-biopsy hemorrhage. This prospective study included pediatric patients who underwent US-guided percutaneous liver biopsies. All children had a US study obtained pre-procedure and one obtained 4-6 h post-procedure; US examinations were deemed positive if abnormalities were present. We also reviewed any subsequent imaging that was performed within 7 days (late imaging) at the discretion of the referring team. Changes in US findings (ΔUS) were graded by two radiologists using a descriptive non-validated scale (none, minimal, marked). Hemoglobin (Hb) levels were assessed pre-procedure and 4 h post-procedure. The diagnostic accuracy of US changes for detecting post-procedural hemorrhage was calculated based on a drop in Hb >1.5 g/dL or Hb >15% from baseline (ΔHb). We used a Kruskal-Wallis test to correlate the ΔHb with ΔUS. Association between late-imaging and post-procedure US findings was tested using a chi-square test. We included 224 biopsies. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of post-procedure US in detecting post-procedure hemorrhage ranged 26.3-42.1%, 72.4-93.3%, 0.22-0.42, and 0.87-0.88, respectively. No significant association was seen between the ΔHb and sonographic findings (P=0.068). No significant difference was seen in the need for late imaging between children who did and those who did not have positive US findings (P=0.814). The sensitivity and PPV of post-procedure US in detecting post-procedural hemorrhage are low. Our findings do not support routine post-procedure surveillance US.