Introduction: Surgical complications (SCs) in renal transplantation are not uncommon in children and may impact outcome. However, reports focused on SCs after pediatric kidney transplantation are few. In this multi-center study, we therefore evaluated incidence and risk factors of early SCs in kidney transplanted children.
Methods: We retrospectively gathered data about pediatric kidney transplantations performed at six centers in Sweden, Norway, and Denmark between 2003-2018 (n=391). An analysis of risk factors and incidence of SCs in this cohort of patients was performed. 
Results: Mean follow-up was 9.6 years. Mean age at transplantation was 8.8 years. The majority were first-time transplantations (96%), 75% received a kidney from a living donor, 59% were dialysis dependent at transplantation and 28% had undergone pretransplant nephrectomy. Extraperitoneal graft placement was chosen in 71% of transplantations and the renal artery most frequently anastomosed to the common iliac artery of the recipient (39%). The incidence of at least one SC first 3 months was 21.7% of patients. Most SCs occurred during the first hospital stay (67% of SCs). First hospital stay was longer in patients with SC (27 days vs 17 days in patients without SC). The most common SC was ureteral leak or stenosis, occurring in 25 patients (6.4%) followed by impaired wound healing and surgical site infection, reported in 5.1%. Thirteen patients experienced vascular thrombosis, stenosis, or torsion (3.3%). Surgical site hemorrhage was reported in ten patients (2.6%) and other abdominal complications described in 4.1%. Within the first 3 months, 76.5% of patients with SC underwent reintervention. Among patients with a body weight below 12 kg, the incidence of SCs the first 3 months was higher compared with bigger children, (43% vs 18%, p<0.000). However, no difference in SCs related to donor source was observed (20% with living donor vs 26% with deceased donor), nor to dialysis dependence (dialysis 24% vs preemptive 20%) or preexisting urologic pathology (26% vs 19% in patients with normal urinary tract). Six patients died within the first year, five with early SC reported. Early vascular complications had a significant negative effect on graft survival (46% 10-year graft survival vs 83% in patients without vascular complications). Patients with early SC had inferior measured GFR at one year post transplant compared with patients without SC (62±25 vs 73±24 ml/min/1.73, p=0.003). Yet, SCs overall did not impact long-term patient survival or graft survival.
Conclusion: This multicenter analysis indicate that surgical complications are common in pediatric renal transplantation, especially in small children. Early surgical complications may significantly reduce graft function and impact first year mortality. Means to reduce surgical complications in pediatric kidney transplantation should be further investigated.