Kidney transplant biopsy adequacy and outcomes in children – is it time for change?

Percutaneous kidney transplant biopsies contribute to the diagnosis of transplant dysfunction and obtaining adequate tissue is crucial. Studies comparing biopsy outcomes according to technique are limited in the paediatric population and report variable outcomes. The aim of this study was to compare the adequacy and complication rates of kidney transplant biopsies performed using the tangential approach to those using the perpendicular approach. This was a retrospective, single-centre cohort study. Clinical, demographic and procedural data were analysed from the electronic medical records of kidney transplant recipients undergoing an allograft biopsy between January 2008 and December 2023. The Banff Classification of Renal Allograft Pathology was used to define sample adequacy. Of 186 included biopsies, 100 (53.8%) were performed by IR and 86 (46.2%) by PN. The overall adequacy rate was 71.5% with a significantly higher adequacy rate in IR-performed biopsies (IR = 90% vs PN = 50%, p < 0.01). IR-performed biopsies had a significantly higher total glomeruli count (26 vs 12 glomeruli, p < 0.01) and glomeruli per core count (10 vs 7 glomeruli per core, p < 0.01). IR-performed biopsies had a significantly higher rate of obtaining one or more arteries (94% vs 69.8%, p < 0.01). There was no significant difference in complication rates between the PN and IR groups. There was an overall adequacy rate of 71% with significantly higher adequacy in IR-performed biopsies using a tangential approach. There were low rates of complications with no significant difference in rates between proceduralists.