The role of 99mtechnetium dimercapto-succinic acid renal scans in the evaluation of occult ectopic ureters in girls with paradoxical incontinence.

PURPOSE: We describe the use of 99mtechnetium (Tc) dimercapto-succinic acid (DMSA) renal scintigraphy to document poorly functioning and/or ectopic renal units associated with occult ectopic ureters.

MATERIALS AND

METHODS

During the last 8 years 6 toilet-trained girls were referred for lifelong continuous urinary dribbling. Initial radiological evaluation included renal and bladder sonography in 6, excretory urography in 4, a mercaptoacetyltriglycine-3 renal scan in 1 and cystovaginoscopy in 2. Ultimately a 99mTc-DMSA renal scan was performed in all 6 girls before surgical intervention.

RESULTS

Sonography failed to establish the diagnosis of ureteral ectopia in all cases, and revealed a normal solitary kidney in 3, normal kidneys in 1, an apparently uncomplicated unilateral duplication without hydroureteronephrosis in 1 and a contralateral uncomplicated duplication in 1. Excretory urography in 4 cases was inconclusive and showed a solitary kidney in 1, ipsilateral duplication without a normal appearing upper pole collecting system in 1, contralateral uncomplicated duplication in 1 and normal kidneys in 1. A mercaptoacetyltriglycine-3 renal scan in another girl with a solitary kidney on sonography failed to demonstrate a contralateral small ectopic kidney. Cystovaginoscopy performed in 2 patients by other pediatric urologists was nondiagnostic. 99mTc-DMSA renal scintigraphy was diagnostic in all 6 cases, and revealed a small poorly functioning ectopic kidney in 3 and a poorly functioning dysplastic upper pole moiety in 3, which were consistent with a diagnosis of ureteral ectopia. An ectopic ureter was confirmed by cystoscopic and surgical findings in all girls.

CONCLUSIONS

99mTc-DMSA renal scintigraphy reliably detects and localizes hypoplastic ectopic kidneys and poorly functioning upper pole moieties associated with occult ectopic ureters in girls with continuous urinary leakage.