Application of renal Doppler sonography in the diagnosis of obstructive uropathy in patients with spinal cord injury.

OBJECTIVES

To assess renal resistive index (RI) changes in patients with spinal cord injury (SCI) who have obstructive uropathy and to determine if an RI of 0.7 or more is useful in identifying such patients.

DESIGN

Prospective cross-sectional study.

SETTING

Rehabilitation hospital affiliated with a medical university.

PARTICIPANTS

A convenience sample of 99 kidneys of 51 SCI patients (38 men, 13 women; mean age, 38.8+/-14.0 y) with neuropathic bladder dysfunction.

INTERVENTIONS

Ultrasonic examination to assess the degree of hydronephrosis, Doppler sonography to calculate renal vascular RIs, and radioisotopic renography to assess renal function and to determine excretory curves. Kidneys were assigned to control or obstructive uropathy groups, and RIs were compared for statistical significance (Student t test) and to assess whether an RI of 0.7 is a distinguishing criterion.

MAIN OUTCOME MEASURES

RI and sensitivity.

RESULTS

Average RIs were .58+/-.07 in the control group (71 kidneys) and .65+/-.08 in the uropathy group (28 kidneys) (P<.001). The sensitivity of using an RI of 0.7 or more to identify patients with obstructive uropathy was 39%. The c statistic of the receiver operating characteristic curve was .72.

CONCLUSIONS

RIs increased in SCI patients with obstructive uropathy. In patients with SCI, urinary findings fit the chronic partial obstruction pattern. A renal RI of 0.7 or more was a poor indicator of obstructive uropathy in such patients.