Living donor liver transplantation in infants 6 kg or less: Impact of graft type and size on postoperative outcomes

Large-for-size grafts (LFSGs), typically defined as those with a graft-to-recipient weight ratio (GRWR) >4%, are traditionally avoided in pediatric living donor liver transplantation due to the risk of abdominal compartment syndrome, vascular complications, and early graft dysfunction. However, in infants weighing ≤6 kg, left lateral segment (LLS) grafts often exceed this threshold, raising concerns about volume reduction. This retrospective study evaluated 97 infants ≤6 kg who underwent living donor liver transplantation at a single center between 2013 and 2024. The primary analysis assessed the entire cohort to identify factors associated with major complications and survival. Subgroup analyses further categorized patients into 4 groups: LLS grafts with GRWR >4% (n=25), LLS grafts with GRWR ≤4% (n=11), reduced grafts with GRWR >4% (n=21), and reduced grafts with GRWR ≤4% (n=40). Major complications occurred in 21 patients (21.6%), and 7 deaths (7.2%) were observed. Univariate analysis for major complications identified only Pediatric End-Stage Liver Disease (PELD) score as significant, while for patient survival, body weight, reduced graft use, and PELD score were significant on univariate analysis; multivariate analysis confirmed only PELD score remained independently associated with mortality. In subgroup analyses, no significant differences were observed among the 4 groups in terms of perioperative outcomes, abdominal closure, or vascular complications. LLS grafts frequently demonstrated a favorable thickness ratio (<1.0), and the ratio of actual graft weight to native liver weight was consistent across groups. These findings indicate that LLS grafts with GRWR >4% can be safely used in selected infants, particularly when volumetric compatibility with the native liver is favorable. Preoperative assessment of graft fit, rather than GRWR alone, may provide a more reliable basis for graft selection in pediatric living donor liver transplantation.