Urinary tract ultrasonography in normal rams and in rams with obstructive urolithiasis.

We determined the position, dimensions, and structure of the kidneys, ureters, bladder, and urethra in 20 healthy, adult rams by use of ultrasonography. The findings were compared with those of seven rams with obstructive urolithiasis, thus establishing criteria for the diagnosis of urolithiasis via ultrasonography. A 5.0 MHz convex transducer was placed over the right paralumbar fossa to examine the kidneys, and a 5.0 MHz linear rectal transducer was used to examine the bladder and urethra transrectally. All examinations were performed on standing rams. The left kidney had a length of 8.4 +/- 0.3 cm (mean +/- SD), a width of 4.7 +/- 0.3 cm, and a depth of 4.4 +/- 0.3 cm. The diameter of the renal sinus of the left kidney was 1.5 +/- 0.2 cm. The circumference of the medullary pyramids measured 2.8 +/- 0.3 cm. Similar ultrasonographic measurements were obtained for the right kidney. The mean diameter of the bladder of 12 rams was 7.5 +/- 2.8 cm. The diameter of the bladder could not be determined in the remaining eight rams because it was greater than 10 cm and therefore beyond the penetration depth of the scanner. The only part of the urethra which could be visualized ultrasonographically was the internal urethral orifice. It had a diameter of 0.2 +/- 0.1 cm.Ultrasonographic examination of seven rams with obstructive urolithiasis revealed a markedly dilated urethra and urinary bladder. Due to severe cystitis, the contents of the urinary bladder appeared as multiple, tiny, uniformly distributed echoes. The renal pelvis and medullary pyramids of both kidneys were dilated in four rams. In two rams, uroperitoneum and accumulation of urine in the abdomen were diagnosed via ultrasonography. In one ram this was due to a ruptured ureter and in one to a ruptured bladder. The results of this study indicate that ultrasonography is a useful aid in the diagnosis of obstructive urolithiasis.