Robot-assisted laparoscopic urologic surgery in infants weighing ≤10 kg: A weight stratified analysis

Robot-assisted laparoscopic (RAL) urologic surgery is widely used in pediatric patients, though less commonly in infants. There are small series demonstrating safety and efficacy in infants, however, stratification by infant size has rarely been reported. Whether a cut-off weight, below which RAL surgery is not technically feasible, safe, or efficacious has not be determined.To assess safety and efficacy of RAL urologic procedures in infants1 year of age, weighing ≤10 kg.A single-institution retrospective cohort study of patients1 year of age, and ≤10 kg undergoing RAL pyeloplasty (RALP) or RAL ipsilateral ureteroureterostomy (RALUU) between January 2011 and September 2020 was performed. Demographic, operative, and post-operative data were extracted from the medical record. Patients were stratified by post-hoc weight quartiles. Outcomes, including operative time, total OR time, estimated blood loss (EBL), post-operative length of stay (LOS), post-operative radiographic improvement, and 30-day complications were assessed by weight quartile for each procedure. The Kruskal-Wallis rank test was used to assess differences in continuous outcomes between weight quartiles and Pearson's Chi-squared test was used for categorical outcomes.Of 696 RAL urologic surgeries performed, 101 met eligibility criteria. Median (IQR) age of patients was 7.2 (6.0-9.2) months with median weight of 8.0 (7.2-8.9) kg. The lowest weight was 5.5 kg. Procedures performed included 79 RALPs (78.2%), 22 RALUUs (21.8%). We identified 97 patients (94%) with post-operative imaging, with radiographic improvement in 92%. When stratified by weight quartile, there was no difference between groups in median operative time, total OR time, LOS, EBL, or post-operative radiographic improvement for both RALP and RALUU. Post-operative complications were assessed based on Clavien-Dindo classification with the majority of complications (9/12, 75%) in the50th percentile weight groups.To our knowledge, this is the largest published series of infant RAL urologic procedures, with similar rates of radiographic improvement and post-operative complications to prior published series. There are few prior series of RALP and RALUU in infants ≤10 kg, and we show comparable outcomes regardless of patient weight. Our study is limited by the inherent biases of retrospective studies.RAL urologic surgery is technically feasible, safe, and efficacious in infants ≤10 kg, without worse outcomes as weight decrease. A cut-off weight, below which RAL surgery should not be performed has yet to be identified.