Bladder stones: radiography or ultrasound to count and measure them

Question

Adult female Bichon Frise with haematuria and pollakiuria. Left lateral abdominal radiograph:

Lateral abdominal radiograph of a female dog with a round radiopaque structure in the bladder region — Image: DrewHeath · CC0, Wikimedia Commons

To decide how to remove the urolith, which statement about imaging is correct?

chevron_right Show answer and explanation

A. If the radiograph shows the stone in the bladder, there is no need to include the urethra

The whole urinary tract must be radiographed, including the entire urethra: urethroliths change the plan and are missed if the view leaves them out.

B. Ultrasound is the best test for counting uroliths and measuring their size

Ultrasound is very sensitive for detecting them, but acoustic shadows overlap and it is less accurate for counting and measuring. To plan treatment, radiography is more reliable if they are radiopaque.

C. A large, smooth, radiopaque urolith in a female dog rules out struvite

On the contrary: in female dogs, large, smooth, radiopaque uroliths are usually struvite associated with infection by urease-producing bacteria, which can be dissolved with diet and antibiotics.

D. Plain radiography counts and measures radiopaque uroliths better than ultrasound

Correct. Radiography shows the number, size and location of radiopaque uroliths more accurately than ultrasound, and these data decide between dissolution, voiding urohydropropulsion or removal. After any removal, repeat the radiograph to check that no fragments remain.

lightbulb Key takeaway

Use ultrasound to detect uroliths (including radiolucent ones) and assess the bladder wall, and radiography to count and measure them and to monitor dissolution. Always include the entire urethra. If the urolith is not radiopaque, ultrasound or double-contrast cystography are the alternatives.

To decide how to remove the urolith, which statement about imaging is correct?

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