Classically, acute kidney injury (AKI) and anuria have been categorized in relationship to the location of the kidney injury: pre-renal, intrinsic, and post-renal. Anuria is defined as less than 100 mL urine per day . True anuria carries a narrow differential that includes vascular lesions, total obstruction, severe acute tubular necrosis (ATN), and severe glomerulonephritis . While the patient’s history and physical exam remain key to narrowing this differential, point-of-care ultrasound (POCUS) can act as an extension of the clinical examination to focus diagnostic workup (Fig. 39.1). POCUS can rapidly identify obstructive uropathy, and contribute to clinicians’ understanding of underlying hemodynamic status and genitourinary anatomy without the added risk of nephrotoxic contrast that other imaging modalities carry .
KeywordsUltrasound Anuria Oliguria Kidney Bladder Acute kidney injury Hydronephrosis Obstruction IVC
Normal kidney long axis (see Fig. 39.8). A normal kidney in the long axis is shown with the cortex, medullary pyramid, and renal sinus labeled. There is no evidence of hydronephrosis as there are no discrete pockets of anechoic fluid in the kidney (WMV 5890 kb)
Moderate hydronephrosis (see Fig. 39.10). Anechoic fluid collects within the pelvicalyceal system. Progressive distortion of the renal structures characterizes the degree of hydronephrosis. The degree is measured by dilation of the renal sinus (mild), then obscuration of the renal papillae and blunting of the pyramids (moderate), and finally to include cortical thinning (severe). Here, moderate hydronephrosis is seen with a dilated renal pelvis (WMV 3361 kb)