Risk stratification for hydronephrosis in the evaluation of acute kidney injury: a cross-sectional analysis

BMJ Open. 2021 Aug 13;11(8):e046761. doi: 10.1136/bmjopen-2020-046761.


Objective: To validate an existing clinical decision support tool to risk-stratify patients with acute kidney injury (AKI) for hydronephrosis and compare the risk stratification framework with nephrology consultant recommendations.

Setting: Cross-sectional study of hospitalised adults with AKI who had a renal ultrasound (RUS) ordered at a large, tertiary, academic medical centre.

Participants: Two hundred and eighty-one patients were included in the study cohort. Based on the risk stratification framework, 111 (40%), 76 (27%) and 94 (33%) patients were in the high-risk, medium-risk and low-risk groups for hydronephrosis, respectively.

Outcomes: Outcomes were the presence of unilateral or bilateral hydronephrosis on RUS.

Results: Thirty-five patients (12%) were found to have hydronephrosis. The high-risk group had 86% sensitivity and 67% specificity for identifying hydronephrosis. A nephrology consult was involved in 168 (60%) patients and RUS was recommended by the nephrology service in 95 (57%) cases. Among patients with a nephrology consultation, 9 (56%) of the 16 total patients with hydronephrosis were recommended to obtain an RUS.

Conclusions: We further externally validated a risk stratification framework for hydronephrosis. Clinical decision support systems may be useful to supplement clinical judgement in the evaluation of AKI.

Keywords: acute renal failure; nephrology; quality in health care.

MeSH terms

  • Acute Kidney Injury* / diagnosis
  • Acute Kidney Injury* / etiology
  • Cross-Sectional Studies
  • Humans
  • Hydronephrosis* / diagnostic imaging
  • Risk Assessment
  • Ultrasonography