Background: Acute kidney injury (AKI) is common in adult hospitalized patients, with the incidence being reported as high as 7.2%. While evaluation of the cause of AKI is often necessary, in hospitalized patients the causes of AKI are more likely to be pre-renal or intrinsic. Previous studies have found that decreased renal perfusion, medications, radiographic contrast media, and sepsis are responsible for AKI in the majority of hospitalized patients. We performed a retrospective analysis of patients who underwent renal sonography for the indication of AKI, and assessed the proportion of those patients who had a scan suggestive of hydronephrosis, as well as those who underwent an intervention to treat hydronephrosis.
Methods: In our retrospective observational study, we conducted a chart review of all adult patients in a large urban community teaching hospital in 2017 who underwent renal sonography after admission with the indication of elevated BUN/Creatinine documented in the electronic health record. We excluded patients who were diagnosed with AKI at admission and any patient with relevant missing information. We collected the baseline characteristics for our patients, including comorbidities, labs at admission, and peak creatinine. We then analyzed the renal ultrasound report and any intervention performed based on that report.
Results: There were 625 patients in the study, with a mean age of 75.2 +/- 15.0, of which 255 (41%) were female. 312 (50%) of the patients had baseline CKD (Stage I to V). Renal ultrasound reports showed only 45 (7.2%) had hydronephrosis, whereas most of them had increased echogenicity (87.8%). Other important findings included cortical thickening (21.4%) and atrophy (5%). Only 4 (0.16%) subsequently underwent any urologic or interventional radiology procedure to address the hydronephrosis.
Conclusions: In this study, only 4 out of 625 patients who underwent renal sonography for hospital acquired AKI had a positive result requiring an intervention. The utility of renal imaging in patients with hospital acquired AKI admitted to a medicine service appears to be limited, and should be investigated more thoroughly by a prospective randomized trial. Meanwhile, hospitals should study ordering patterns of renal sonography and consider implementing high value measures for appropriate ordering of this test.