Introduction:There are increased challenges in transplanting small (<20kg) recipients rendering implantation infeasible or, at best, uncertain. In this context, transplant feasibility is dependent on a multi-disciplinary approach where unconventional interventions may be required. This study evaluates 3 key aspects of transplantation in small children from a large volume combined tertiary UK Paediatric Transplant Centre:

1) A comparative analysis of 350 patients (from 2005-2014) to determine any difference in patient and graft survival in children weighing <20 kg (group1) compared to >20kg (group2) at the time of transplant?

2)Where do we perform graft anastomoses in presence of vascular anomalies?

3)How can we make paediatric transplantation safer? Surgical decisions currently rely on 3D imaging which is limited in evaluating structures by their presentation on 2D screens. As a solution, we assessed the feasibility of using 3D printing technology to fabricate physical models portraying patient-specific anatomy and disease morphology. 

Methods: Data was evaluated from a prospectively collected UK Registry (NHSBT) database. We also retrospectively reviewed 5 children with significant vascular anomalies. We prospectivley assessed the value of 3D printing to inform complex transplantation using questionnaires (score 1-5, 1=not useful, 5= very useful).

Results/Discussion: There was no significant difference in graft (p=0.239) or patient (p=1.06) survival between Group1 (<20kg) and 2(>20kg) on Kaplein-Meier analysis. Outcomes for 5 complex vascular cases shown in Fig1. This group had 100% death censored graft survival and median eGFR 46 mls/min/1.73m2 at 10 month median follow up. A prospective 3D model (Fig.2) was printed for a 2 year-old male (10.2 kg with major previous abdominal surgery) for living donor transplantation from his father. The operating surgeon confirmed intra-operative geometric correlation of vessel anatomy and spatial relations between the model and the patient during surgery. The family found the models useful for consenting (all scored 5).

Conclusions: Our large cohort analysis shows transplantation is feasible and safe with comparable outcomes in smaller weight children with respect to graft and patients survival.  Furthermore, vascular anomalies do not necessarily preclude transplantation where unconventional anastomotic approaches may be required. Finally, to our knowledge this is the first reported case of using novel 3D printing in paediatric renal transplantation. Our experience proves promising with clinical translation of these models into the operating theatre, providing the surgical team with full 3D haptic spatial appreciation for making critical decisions – in particular, aiding the accurate placement of adult size donor kidney into the paediatric abdomen.