Point-of-care ultrasound for the early diagnosis of emphysematous pyelonephritis: A case report and literature review

BACKGROUND Emphysematous pyelonephritis(EPN) is a rare but fatal necrotic infection of the kidney, which usually leads to septic shock. Therefore, early diagnosis and optimized therapy are of paramount importance. In the past two decades, pointof-care ultrasound(POCUS) has been widely used in clinical practice, especially in emergency and critical care settings, and helps to rapidly identify the source of infection in sepsis. We report a rare case in which a "falls" sign on POCUS played a pivotal role in the early diagnosis of EPN.CASE SUMMARY A 57-year-old man presented with fever and lumbago for 3d prior to admission. He went to the emergency room, and the initial POCUS detected gas bubbles in the hepatorenal space showing a hyperechoic focus with dirty shadowing and comet-tail artifacts. This imaging feature was like a mini waterfall. His blood and urine culture demonstrated Escherichia coli bacteremia, and EPN associated with septic shock was diagnosed. The patient did not respond to broad-spectrum antibiotic treatment and a perirenal abscess developed. He subsequently underwent computed tomography-guided percutaneous catheter drainage, and fully recovered. We also review the literature on the sonographic features of POCUS in EPN.CONCLUSION This case indicates that a "falls" sign on POCUS facilitates the rapid diagnosis of severe EPN at the bedside.