Acute kidney injury (AKI) is a common diagnosis in the emergency department (ED), and urinary tract obstruction is a contributing cause that requires rapid diagnosis and therapeutic management. This observational study aims at assessing the accuracy of point-of-care ultrasound (POCUS), performed by the emergency physician (EP) for the detection of dilatation or distension of the kidney secondary to urinary tract obstruction, in emergency department patients presenting with acute kidney injury (AKI). Participants will undergo a bedside POCUS of the urinary tract by the EP followed by central imaging evaluation by a radiologist (either ultrasound or renal computed tomography (CT) or both). Researchers will compare both diagnosis. Study hypothesis is that trained emergency physicians can rapidly and reliably diagnose renal tract obstruction at POCUS in the context of AKI.

Acute kidney injury (AKI) is a common diagnosis in the emergency department (ED), and urinary tract obstruction is a contributing cause that requires rapid diagnosis and therapeutic management. Hydronephrosis is a dilatation or distension of the kidney secondary to urinary tract obstruction. It can be diagnosed at ultrasonography or computed tomography. Assessment of the renal tract and detection of hydronephrosis is a core component of the emergency medicine Point-of-Care Ultrasound (Pocus) curriculum. The primary objective of this study is to compare the performance of point-of-care ultrasound performed by the emergency physician to that of central radiology imaging (US or CT) by a radiologist, to diagnose hydronephrosis in patients presenting with AKI in the ED. All imaging exams will be performed as part of routine evaluation, Pocus will be carried out by a trained EP blinded from radiology imaging results.

Inclusion Criteria:

• Patient with acute kidney injury defined by changes in serum creatinine (sCr) level between the index sCr at ED admission and pre and/or post sCr controls (Kidney Disease Improving Global Outcome criteria)
• Patient who does not oppose to the use of their data

Exclusion Criteria:

• Vesical globe
• Polycystic kidney disease
• Known renal tumor
• Horseshoe kidney

Patients admitted to the emergency department of Montpellier university hospital