A novel image-guided size-matching strategy enables living-donor kidney transplantation in very small pediatric recipients

Introduction: Safe implantation of adult living-donor kidneys in very small children remains one of the most challenging situations in pediatric kidney transplantation. Existing preoperative assessment relies largely on anthropometric surrogates and surgical judgment and does not directly determine whether a graft can be accommodated within the recipient abdomen. We developed a novel, patient-specific planning strategy that combines dialysis fluid-enhanced recipient CT, virtual graft placement, and true-scale 3D-printed donor kidney models to enable objective preoperative assessment of donor-recipient anatomical fit. The overall workflow is summarized in Figure 1.

Methods: This proof-of-concept case series included three pediatric recipients weighing less than 20 kg who were scheduled for living-donor kidney transplantation. Recipient abdominal CT was performed after intraperitoneal instillation of dialysis fluid via the peritoneal dialysis catheter to delineate the available intraperitoneal space. Donor kidneys were segmented from donor CT and virtually positioned within each recipient dataset using dedicated imaging software. Simulations were used to assess graft orientation, clearance to the abdominal wall, and relationships to adjacent organs and major vessels. True-scale 3D-printed donor kidney models were produced to corroborate graft dimensions and support multidisciplinary preoperative decision-making. A representative case with orthogonal CT overlays and multi-angle 3D renderings is shown in Figure 2. 

Results: In all three cases, the combined virtual and physical simulations demonstrated feasible graft accommodation and enabled selection of adult living-donor kidneys for transplantation. All three children subsequently underwent successful transplantation without intraoperative complications related to graft fit, limited intra-abdominal space, or abdominal wall closure. No abdominal compartment syndrome, graft-compression events, or wound-closure complications occurred. At 6 months, graft survival was 100%, no child required dialysis reinstitution, mean serum creatinine was 35.0 µmol/L, and mean estimated glomerular filtration rate was 94.4 mL/min/1.73 m².
Conclusion: This study introduces a novel and clinically actionable strategy for preoperative size matching in very small pediatric kidney transplant recipients. By replacing indirect size estimates with direct, patient-specific simulation of graft accommodation, this approach may overcome a major barrier to earlier living-donor transplantation in small children. The method has the potential to improve surgical confidence, reduce avoidable dialysis exposure, and establish a foundation for future AI- and mixed reality-assisted transplant planning.