Posterior urethral valve: transperineal US for imaging and diagnosis in male infants.

PURPOSE: To compare routine pelvic and transperineal scanning in the ultrasonographic (US) diagnosis of posterior urethral valve (PUV). MATERIALS AND METHODS: Longitudinal and transverse transperineal views were obtained in addition to routine renal and transvesicle views in the prospective US evaluation of 10 male infants (aged 2 days to 6 weeks) clinically suspected of having PUV. High-frequency (5.0- and 7.5-MHz) transducers were used. RESULTS: Five of the boys proved to have PUV. Each had urethral dilation clearly imaged at transperineal US. Only two of these boys had urethral dilatation imaged with the transvesicle approach. In three of the boys, a linear area of echogenicity, consistent with a valve, was imaged, but only with the transperineal approach. The other five boys had no urethral dilatation noted at transperineal or transvesicle US and proved to not have PUV. CONCLUSION: Transperineal imaging can aid in the diagnosis of PUV at US. Transperineal US may enable imaging of the valve itself.