Clinical Heterogeneity of Refractory Ascites After Pediatric Liver Transplantation Modulates Allograft Rejection Risk.

Refractory ascites (RA) is a severe complication that impedes long-term survival after pediatric liver transplantation (LT), but its etiology remains complex and heterogeneous. To systematically evaluate the prognostic impact, clinical risk factors, and immunological features of RA, we retrospectively analyzed 1455 pediatric recipients who received LT in Renji Hospital between October 2016 and December 2021. RA was associated with increased mortality and graft loss after pediatric LT. Univariate analysis identified 13 clinical factors associated with RA, whereas a preliminary multivariable model showed only moderate discrimination, suggesting substantial heterogeneity among RA patients. Based on unsupervised clustering of clinical parameters, RA individuals were classified into two subgroups. Type I ascites was mainly associated with low graft-to-recipient weight ratio, decreased preoperative white blood cell count, and platelet count, indicating the involvement of persistent portal hypertension. In contrast, type II ascites was characterized by ABO incompatibility, elevated early postoperative soluble IL-2 receptor, and increased risk of T-cell-mediated rejection, suggesting excessive alloimmune activation. These findings indicate that RA after pediatric LT comprises distinct clinical entities with different pathogenic implications. Prudent graft selection and close monitoring of immune status may help prevent RA and improve post-transplant outcomes.