Impact of ABO and Rh Incompatibility on Early Postoperative Outcomes in Pediatric Liver Transplantation: A Single-Center Cohort Analysis of 99 Recipients

Background: Serologic compatibility, particularly ABO and Rh blood group matching, has long been considered a potential determinant of early outcomes in pediatric liver transplantation. Although the liver possesses unique tolerogenic properties that reduce susceptibility to antibody-mediated injury, the clinical significance of ABO and Rh mismatch in children remains insufficiently defined. Existing literature focuses predominantly on ABO incompatibility, while the impact of Rh disparity—despite its frequent occurrence—has never been systematically examined in a pediatric cohort. Objectives: This study aimed to evaluate the influence of ABO and Rh mismatches on early postoperative outcomes, including biliary complications, EBV seroconversion, and CMV infection, in a contemporary pediatric liver transplant population. Methods: A retrospective single-center cohort of 99 pediatric liver transplant recipients between 2022 and 2025 was analyzed. ABO and Rh compatibility were assessed using standard serologic methods. Early postoperative outcomes—biliary complications, CMV infection, EBV seroconversion, early graft dysfunction, vascular events, and acute rejection—were systematically recorded. Comparative analyses were performed between matched and mismatched groups; Rh mismatch was further evaluated through multivariable logistic regression. Results: Major ABO incompatibility was present in only 1 patient (1.0%), while 11 patients (11.1%) had Rh mismatch. Across all primary and secondary outcomes, neither ABO nor Rh mismatch was associated with increased early postoperative morbidity. Biliary complications occurred in 13 patients (13.1%), but none in the ABO-incompatible or Rh-mismatched groups. EBV seroconversion developed in 14 patients (14.1%); rates were similar between Rh-compatible (68.2%) and Rh-mismatched recipients (72.7%; p = 1.00). CMV infection occurred in 5 patients (5.1%), with no significant difference between groups (p = 1.00). All vascular complications and biopsy-proven rejection episodes occurred exclusively in serologically compatible pairs. Multivariable analysis showed no independent association between Rh mismatch and biliary morbidity, EBV seroconversion, or CMV infection. Early graft and patient survival were 100% in both ABO- and Rh-mismatched recipients. Conclusions: In this pediatric cohort, Rh mismatch demonstrated no adverse clinical impact, and the single ABO-incompatible graft did not experience early complications. These findings support the concept that pediatric liver recipients—owing to developmental immunologic tolerance—may be uniquely resilient to serologic disparities. While ABO incompatibility remains too rare for firm conclusions, Rh incompatibility appears clinically inconsequential and should not limit donor availability in pediatric transplantation. Larger multicenter studies are warranted to confirm these observations and refine allocation strategies.