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 (LDLT) 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 LDLT 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 four 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 seven 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 four 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 LDLT.