Septic acute kidney injury (AKI) accounts for more than half of all cases of AKI in critically ill children. The renal histology was found to alter the management in more than two-third of cases of adult acute renal failure. Better insight into the pathogenesis of pediatric septic AKI could be based on developing a clearer appreciation of the histopathological changes. No comprehensive study of the histopathological features of septic AKI in critically ill children has yet been performed.

This retrospective observational study was conducted at a level-III pediatric intensive care unit (PICU) from June 2013 to July 2014. Children (<13 years of age) who had expired due to sepsis and AKI and had post-mortem renal biopsies were included. Sepsis and AKI were defined according to the International pediatric sepsis consensus conference and Acute Kidney Injury Network (AKIN) definition and classification system, respectively.

A total of 708 patients were admitted to the PICU during the study period, with mortality of 24 % (n = 170) and 62 complete data of post-mortem renal biopsies were included. The median (IQR) age was 12 (4.8–36) months, pediatric risk of mortality score (PRISM) III was 14 (12–18) and the time to biopsy after death was 24 (18–26) minutes. Normal histology was the most common change 41.9 % (n = 26), followed by acute tubular necrosis (ATN) 30.6 % (n = 19). A combination of changes involving tubules, glomeruli, interstitium, and blood vessels was noted in 21 % (n = 13) of the specimens. Eight percent (n = 5) of the specimens had features consistent with thrombotic microangiopathy. Normal histology was noted in 15.4 % (n = 4/26), 50 % (n = 13/26), and 34.6 % (n = 9/26) of AKI stage-I, II, and III, respectively.

The most common renal histopathological change in septic AKI in critically ill children was normal histology followed by ATN.