Is renal scintigraphy really a necessity in the routine diagnosis of congenital solitary kidney?

Background: For a definitive diagnosis of congenital solitary kidney, renal scintigraphy is suggested as being the gold standard of ruling out ectopic functioning renal tissue, possibly missed by ultrasound. The aim of our study was to test ultrasonography precision in comparison with renal scintigraphy on a larger cohort of congenital solitary kidneys.

Methods: We performed a retrospective unicenter study of children with congenital solitary kidney with no contralateral tissue, who were treated in the period from 1980 to 2017. The findings in children who underwent both abdominopelvic ultrasound and nuclear renal scintigraphy were compared and the accuracy of ultrasound was assessed.

Results: 99 children met the inclusion criteria of congenital solitary kidney confirmed with abdominopelvic ultrasound and nuclear renal scintigraphy. The children were predominantly male (61.6%), and the congenital solitary kidney was largely right-sided (55.5%). In 97 cases (98%), ultrasound correctly predicted the absence of functional renal tissue on one side in the renal fossa or in an ectopic location (pelvis or ipsilateral side). The calculated accuracy of abdominopelvic ultrasound in diagnosing congenital solitary kidney was therefore 98%.

Conclusions: Our findings confirm that abdominopelvic ultrasound alone is accurate enough to diagnose congenital solitary kidney. It gives enough information for consideration if further radiological evaluation is still needed.