When an auditor stripped acute tubular necrosis (ATN) from an inpatient claim, downcoding the MS-DRG because there was no kidney biopsy, the hospital had a good case on appeal. Biopsies are not expected when physicians diagnose the cause of ATN and acute kidney injury (AKI), such as a serious decrease in kidney function after the use of contrast in imaging, one expert says.

“In the real world, [kidney] biopsies are not routinely done. They’re usually not needed to make a diagnosis,” said Karla Hiravi, director of clinical audit and appeal services at AppealMasters in Towson, Maryland. “Most of the time, the causes of acute kidney injury are very clear.” However, according to Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for Acute Kidney Injury (AKI), “if the cause of acute kidney injury isn’t clear after careful evaluation, renal biopsy should be considered.” Primary indications for biopsy are glomerular hematuria/proteinuria with or without renal dysfunction and unexplained renal failure.