Ultrasound of the kidneys and bladder can yield helpful diagnostic information for patients presenting with symptoms of urinary retention, decreased urinary output, or abdominal/flank pain consistent with renal colic. Obstructive uropathy due to kidney stones is the principal pathology identified with emergency physician–performed renal ultrasound. Bladder volume is easily calculated by viewing and measuring the bladder in two planes. In focused renal ultrasound, the goal is not to identify renal or ureteral calculi; rather, the kidneys are evaluated for hydronephrosis. The presence of hydronephrosis in the patient with renal colic is presumed to be a direct result of ureteral obstruction. There are no accurate means of determining the degree of obstruction by the presence of hydronephrosis.
Decreased urinary output
The recommended sonographic approach to the kidney is similar to that for the RUQ and LUQ windows in the E-FAST examination previously discussed, with the probe angled toward the retroperitoneum for better views of the kidneys. The coronal view allows the sonographer to visualize the right or left kidney from the superior to inferior poles. Transverse or axial views of the entire kidney should be obtained as well. Renal EUS is most easily interpreted when comparative images are obtained between the right and left kidneys. The bladder view is also nearly identical to that of the E-FAST exam described earlier. However, rather than focusing on the potential spaces of the peritoneum, attention is focused on the bladder and its contents.
Views for Emergency Department Renal and Bladder Ultrasound
Coronal or sagittal kidney view
Transverse kidney view
Sagittal bladder view
Transverse bladder view
Equipment: Recommended Transducers for Renal Ultrasound
Kidney: Right and Left Coronal Views
The transducer indicator is oriented toward the patient’s head.
The transducer is directed as a coronal section through the body in the mid to posterior axillary lines (Fig. 24.83). Begin scanning between the 9th and 11th ribs on the right and the 8th and 11th ribs on the left.
Identify the liver, right kidney, renal cortex (with pyramids), and central renal sinus (Fig. 24.84).
Identify the spleen, left kidney, renal cortex (with pyramids), and central renal sinus.
Renal Ultrasound. The transducer is directed as a coronal section through the body in the mid to posterior axillary lines. (Photo contributor: Lawrence B. Stack, MD.)