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February 2008
By Phillips Perera, MD, RMDS, and Diku Mandavia, MD, FACEP, FRCPC
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Presentation:
A 28-year-old man has come to your emergency department for evaluation of sudden, severe pain in his right flank that began four hours ago. He reports that the pain is intense, constant, radiating to his groin, and associated with nausea and vomiting and that he has never had an episode like this before.
The patient seems very uncomfortable and is constantly moving around on the bed. His vital signs are: heart rate, 100; blood pressure, 130/80; temperature, 99?F; respirations, 12. He has right flank tenderness and a urine dipstick test reveals 2+ blood. You order morphine and ketorolac to be given intravenously and wheel the ultrasound machine to the bedside. A scan of both kidneys and the bladder confirms your diagnosis. The image above shows the affected right kidney.
Click for diagnosis and discussion |
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Diagnosis and discussion:
The ultrasound image shown on the first page demonstrates renal hydronephrosis. The dilatation of the renal calyces is consistent with obstruction of the outflow system by a calculus. Note the dark or anechoic areas of fluid within the calyceal collecting system that have coalesced to form a dilated ureter. Compare that image with the very different appearance of the patient’s normal kidney on this page. The clinical picture and findings of unilateral hydronephrosis and hematuria are indicative of renal colic.
Some stones may be visualized in the renal parenchyma or at the ureteropelvic junction in the proximal ureter. The bladder should always be included in the ultrasound since it will occasionally reveal stones at the ureterovesicular junction. The degree of hydronephrosis can be estimated by the amount of dilation of the collecting system on ultrasound. Low-grade hydronephrosis will appear as multiple small, central, fluid-filled areas that coalesce on close examination and connect to the ureter. High-grade hydronephrosis will completely shell out the renal pelvis into a large, dark, fluid-filled area with a thinned outer cortex.
Renal cysts can occasionally be confused with low-grade hydronephrosis, but unlike the fluid-filled areas seen in hydronephrosis, most cysts are peripheral in location and do not connect to the central calyceal collecting system. It should be noted that the degree of hydronephrosis does not necessarily correspond to the size of the stone, but is related to the patient’s hydration status and the duration of renal obstruction.
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Dr. Perera is an assistant clinical professor of emergency medicine at Columbia University College of Physicians and Surgeons and Weill Cornell Medical College and director of emergency ultrasound at New York Presbyterian Hospital in New York City. Dr. Mandavia is a clinical associate professor of emergency medicine and director of emergency ultrasound at Los Angeles County-USC Medical Center and an attending staff physician at Cedars-Sinai Medical Center in Los Angeles.
Emerg Med 40(2):19-20, 2008
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