Real-time renal sonography in spinal cord injury patients: prospective comparison with excretory urography.
A prospective blinded comparison of real-time renal sonography and excretory urography was done in 202 urologically asymptomatic patients with spinal cord injury who underwent periodic evaluation. Sonography identified 31 of 31 renal masses (100 per cent) (30 cysts and 1 xanthogranulomatous pyelonephritis), whereas excretory urography identified 14 of 31 masses (45 per cent). Of the 398 kidneys evaluated hydronephrosis owing to an obstructive etiology was noted in 7, all of which (100 per cent) were identified on excretory urography and 6 (86 per cent) were identified on sonography. Only 12 of the 48 kidneys (25 per cent) with typical changes of chronic pyelonephritis on excretory urography were diagnosed correctly by ultrasound. Sonography identified 18 of 23 kidneys (78 per cent) with calculi compared to 20 of 23 (87 per cent) by excretory urography. Although 127 abnormalities were noted in 202 patients, only 21 dictated a change in management. Thirteen abnormalities were visible on a plain film of the kidneys, ureters and bladder (3 kidneys with stones, 1 ureteral stone and 9 bladders with stones). We conclude that sonography and excretory urography are excellent diagnostic modalities for the evaluation of the kidneys. Sonography, plain radiograph of the abdomen and post-contrast injection x-rays on excretory urography frequently offer complementary diagnostic information. The noninvasive nature of ultrasound examination and lack of x-ray exposure combined with no need for special patient preparation make ultrasound examination extremely attractive in this patient population. It is recommended that real-time renal ultrasound and a plain radiograph of the abdomen be used on an alternate basis with excretory urography for the routine followup of spinal cord injury patients.