Just Another "UTI"? A Case of Renal Obstruction Diagnosed by Point-of-Care Ultrasonography

Introduction The role of physician-performed ultrasound in patients with urinary tract infection and fever is currently undefined. We report a case of a clinician’s use of ultrasound as a diagnostic aid in an atypical... [ view full abstract ]

Introduction
The role of physician-performed ultrasound in patients with urinary tract infection and fever is currently undefined. We report a case of a clinician’s use of ultrasound as a diagnostic aid in an atypical presentation of renal obstruction.

Case Presentation
A healthy 45-year-old female presented to an outpatient urgent care facility with a 3-day history of fever without other localizing symptoms. She had a negative influenza test, was diagnosed with an upper respiratory infection and prescribed azithromycin. The next morning, the patient presented to the Emergency Department (ED) with continued fever and new vomiting, with a review of symptoms positive for intermittent flank pain and lower extremity pain that the patient attributed to muscle aches. The physical exam was remarkable for possible reduced breath sounds on the right lung base and no reproducible flank tenderness. She underwent bloodwork, urinalysis, and chest radiography. This testing was normal except for the urinalysis which showed large leukocyte esterase, negative nitrites, 4 RBC and 109 WBC/hpf. She was diagnosed with a urinary tract infection and possible early pyelonephritis, treated with ceftriaxone and sent home with oral sulfamethoxazole and trimethoprim. The patient had worsened vomiting and returned to the ED later that day. The patient received intravenous fluids and antipyretics. She began to improve, so the patient was considered for discharge. Prior to this, an Internist training in the use of portable ultrasounds performed a focused assessment of the kidneys and bladder and discovered right-sided hydronephrosis indicating a renal obstruction. A CT confirmed marked hydronephrosis and showed a 1.7cm obstructing stone at the ureteropelvic junction. She was admitted to the hospital where she underwent cystoscopy and insertion of a right ureteral stent to facilitate stone passage. The patient eventually made a full recovery.

Discussion
This case highlights the utility of point-of-care ultrasound (POCUS) as a tool in the evaluation of patients with suspected pyelonephritis, assisting in the diagnosis of obstructive nephrolithiasis resulting in the appropriate procedure for source control of the infection. Although guidelines exist on when to use imaging in patients with urinary tract infections, these guidelines do not currently account for the increasing availability and integration of POCUS into medical decision making. For several different applications, POCUS has been shown to improve diagnostic accuracy, reduce complications, improve patient satisfaction, and reduce medical costs. Further study on the role of POCUS in patients with undifferentiated fever and urinary tract infections is warranted.