Purpose or Case Report: Doppler ultrasound (DUS) is routinely used to assess graft status after liver transplantation (LT). Although early post-surgical assessment is encouraged, the exact prognostic value of DUS parameters is unknown.

The purpose of this study was to determine the prognostic value of DUS parameters obtained in the immediate postoperative period.
Methods & Materials: We included all children (<18 years) receiving a primary LT at our center from 2000 to 2019 who were assessed with DUS within 12 hours after LT. Our primary outcome was development of any graft-related complication requiring invasive management.

Descriptive statistics were presented in absolute values, percentages, median and interquartile range (IQR). Associations between predictors and outcomes were determined using univariate and multivariable logistic regression and expressed as odds ratio (OR) or adjusted odds ratio (aOR) with 95% confidence intervals (95%CI). Receiver operator characteristic curve analysis was used to find optimal thresholds for predictors.
Results: Our sample included 79 liver recipients with a median age of 1.3 years (0.72 – 7.2), 25 (44%) were females and 45 (57%) had a living donor. The median time between LT and DUS was 1.8 hrs (1.1 – 3.9); 61 (77%) within 4 hrs.

Twenty-eight (35%) patients required invasive management, with a median time to detection of 11 days (IQR 4 - 46) . The most common complications were portal vein thrombosis (10, 21%), biliary leak (9, 19%), and biliary stricture (7, 15%). The median follow-up was 3.16 years (IQR 1.5 – 7.0). Two of these 28 patients had vascular complications detected on the immediate post-op scan.

Univariate analysis showed that the median (IQR) portal vein velocity (PVV) distal to the anastomosis was lower in complicated grafts [43 (20 - 59) vs 60 (40 – 94), p=0.008]. The optimal cutoff value was <60 cm/s (sensitivity=81%, specificity=54%, AUC=0.69, 95%CI: 0.57 - 0.82). No other clinical or DUS parameter showed statistically significant differences in patients that required intervention vs mildly or uncomplicated grafts.

A multivariable regression analysis showed an approximately 5 -fold higher odds of requiring invasive management with a PVV<60 cm/s, compared with PVV≥60 cm/s, after adjusting for age, sex, graft type, operation time and hepatic artery peak systolic velocity (aOR 5.3; 95%CI 1.5-17.6, p=0.007).
Conclusions: Immediate DUS assessment detects immediate complications and identifies patients at risk of complications through the PVV distal to the anastomosis.