24-19: Renal and Bladder Ultrasound

Clinical Summary

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.

Indications

• Flank/abdominal pain

• Renal colic

• Hematuria

• Urinary retention

• 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

1. Coronal or sagittal kidney view

2. Transverse kidney view

3. Sagittal bladder view

4. Transverse bladder view

Equipment: Recommended Transducers for Renal Ultrasound

• Convex array

• Phased array

Patient Position

• The patient is supine.

• Alternatively, the patient may be placed in a prone position with the probe placed in the midscapular line and the transducer directed toward the abdomen.

Technique

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.