Use of sonography and radioisotope renography to diagnose hydronephrosis in patients with spinal cord injury

Objective: To study the accuracy of sonography and radioisotope renography in detecting hydronephrosis in patients with spinal cord injury (SCI). Design: Prospective, blinded comparison study. Setting: Rehabilitation hospital affiliated with a medical college. Participants: One hundred and nine patients with SCI (21 women, 88 men) par ticipated. Interventions: Comprehensive urologic examinations including clinical evalu ation, laboratory tests, intravenous urography (IVU), sonography, radioisot ope renography (renal scan), voiding cystourethrography, and cystometry. Th e findings at sonography and renal scan were separately compared with the f inal diagnosis interpreted by IVU and clinical findings. Main Outcome Measures: Effective renal plasma flow, pyelocaliectasis, and p ositive and negative predictive value. Results: A total of 235 kidneys were analyzed. Sonography correctly exclude d the presence of hydronephrosis in 173 of 192 nonobstructed kidneys. Sonog rams were interpreted as positive in 41 of 43 kidneys with documented hydro nephrosis. Renal scan correctly excluded 161 nonobstructed kidneys. The ren al scan detected 39 of 43 kidneys with hydronephrosis. The sensitivity of s onography was .96 with a specificity of .90. Renal scan reached a sensitivi ty of .91 with a specificity of .84. Conclusion: Sonography and renal scan are safe, sensitive, and specific for detecting hydronephrosis. Combined use of both methods appears to be a rel iable alternative to IVU in the long-term follow-up for patients with SCI w ith neurogenic bladder dysfunction.