Hydronephrosis

This week we had a great image of hydronephrosis from by Drs. Stephanie Kahn and Susan Podolsky. The patient presented with the acute onset flank pain. In the work up, bedside US was used to further evaluate for suspected pathology.

The attached image shows the kidney in long-axis. Note the large anechoic area in the echogenic renal pelvis. This is considered moderate hydronephrosis – which can be seen in obstructive uropathy. Dr. Kahn and Dr. Podolsky went one step further by using Color Flow Doppler to show the anechoic area of the renal pelvis was not vascular in origin (absence of color flow); rather, representative of urinary dilation of the renal pelvis.

Bedside ultrasound does not commonly detect renal stones, rather it has excellent ability to detect hydronephrosis.  It can be challenging to determine the degree of hydronephrosis.  See the schematic below as a guide.

The presence of unilateral hydronephrosis or hydroureter in the setting of hematuria and acute flank pain is very suggestive of the presence of a ureteral stone. Comparison views of the R and L kidneys should always be done.