#3089 Radiological assessment of suspected acute pyelonephritis in the management of urosepsis and prevention of acute kidney injury
Authors: Thornton Johnny , Wall Catherine , Mcevoy Caitriona , Ward Francis , Halpenny Darragh , Lavin Peter , Egan Allyson C 
Published: May 2024

Abstract

Background and Aims
Sepsis, a serious complication of infection, may result in organ dysfunction and is responsible for almost 20% of global deaths. Identification of acute pyelonephritis (pyelo), requires early clinical assessment, diagnostics and antimicrobial therapy to prevent septic shock and potential death. In 2022, the American College of Radiology (ACR) published a revised appropriateness criteria for radiological imaging in suspected acute pyelo (1). Five variant [V] categories were defined according to presence of pregnancy, stone disease, renal transplantation, complicated (i.e. recurrent pyelo, DM, immunosuppression) and uncomplicated (first) presentation. The aim of this project was to establish the proportion of patients with suspected acute pyelonephritis undergoing radiological assessment, the selected modality and radiological findings, which could contribute to the diagnosis and management.

Method
This observational retrospective study of 55 cases with suspected acute pyelo over 6 months. Patients who were decanted to nephrology specialist care from the acute medical take were assessed. Patients were grouped into 5 categories [Variant 1-5] as per appropriateness criteria of the ACR (Table 1a). Patient demographics, renal function and signs of sepsis were recorded. The proportion undergoing radiological assessment, the modality and outcomes are outlined in Table 1.

Results
Demographically, 66% of patients were female, the median age was 49 years [IQR 30] and 93.6% were Caucasian. Pre-admission baseline Creatinine (Cr) was 75 µmol/l [IQR 75]. Admission Cr was 85 µmol/l [IQR 74}, with peak inpatient Cr 94 µmol/l. Sepsis parameters (hypotensive/ tachycardia/ high CRP) on admission were observed in 38% of patients. Modality Choice 92.7% of study participants received imaging over the course of their inpatient stay. The primary modality of choice was CTKUB (36.4%), with 25.5% of patients receiving targeted ultrasound. In the setting of uncomplicated acute pyelo (V1), CTKUB was the most common diagnostic modality. Patients with a history of renal calculi (V3) were imaged equally with CTKUB and targeted ultrasound (42.9% CTKUB vs. 42.9% USS). Patients with a history of renal transplant with a native kidney in-situ were most commonly investigated with targeted ultrasound to assess for acute pyelo 92.3%. Imaging Results 52.7% of imaging had positive findings. Most frequently recorded was pyelo (23.6%), renal/ureteric calculi (16.4%) and hydronephrosis (12.7%). In presumed uncomplicated acute pyelo (Variant 1), 29% of patients had radiological evidence of pyelo. 22.2% had newly diagnosed renal/ ureteric calculus. 11.1% had hydronephrosis. One patient had both stones and hydronephrosis. In known stone disease, two presented with hydronephrosis [V3]. Two transplant cases had hydronephrosis [V5].

Conclusion
Early detection of pyelonephritis and its underlying aetiology is imperative in the management of urosepsis. Results suggest 22.2% had newly diagnosed renal/ ureteric calculus in those not known to have renal disease [V1]. In total 12% had hydronephrosis, and nearly a quarter had pyelo visible on imaging. No abscesses were observed which guided duration of antibiotic therapy. Early intervention including anti-microbial therapy and management of acute kidney injury were guided by imaging outcomes. Access to specialist services and early imaging is crucial in successful outcomes in urosepsis.