[Contribution of ultrasound signs for the prenatal diagnosis of posterior urethral valves: Experience of 3years at the maternity of the Bicêtre Hospital].

OBJECTIVES

Posterior urethral valves (PUV) are the most common cause of renal impairment in boys during early childhood. The aim of this study was to evaluate the value of ultrasound (US) criteria currently used to diagnose PUV.

MATERIALS AND METHODS

From 2009 to 2012, 31 patients were referred to the Bicêtre Hospital after detection of fetal bilateral hydronephrosis in male fetus. The ultrasound criteria were bladder dilation, thick-walled bladder, urethral dilation ("keyhole sign"), and amniotic fluid volume. Patients were divided in two groups: suspected or not to have PUV.

RESULTS

US diagnosis of PUV was done in 18 fetuses and confirmed in 14 new borns, one of them without prenatal diagnosis. Sensitivity and specificity of US scan were 92.8 and 66.7%. The likelihood ratio (LHR) was 4.8 for a thick-walled bladder, 4.2 for oligohydramnios, 3.6 for the "keyhole sign", 2.4 for bladder dilation and 1.6 for ureteral dilation. The first four signs were combined in four fetuses, all of them with PUV.

CONCLUSION

US scan is a very sensitive exam for the diagnosis of PUV but with a low specificity. A thick-walled bladder seems to have a better diagnostic performance than the "keyhole sign".