The Pubic Diastasis Measurement, a Key Element for the Diagnosis, Management, and Prognosis of the Bladder Exstrophy.

OBJECTIVE: To demonstrate the feasibility of measuring the fetal pubic diastasis (PD) distance on antenatal ultrasound in normal fetuses and to compare it to fetuses with bladder exstrophy.

METHODS: Firstly, a prospective multicentric study was conducted to determine the feasibility of the PD ultrasound measurement during the second half of pregnancy. Secondly, data from a single center were used to develop a nomogram for PD values in normal fetuses. Thirdly, retrospective PD measurements were collected from fetuses with bladder exstrophy, diagnosed in seven French Multidisciplinary Centers for Prenatal Diagnosis (MCPDs).

RESULTS: Operators from several MCPDs examined 868 fetuses and found that overall PD ultrasound measurement was feasible in 71% of cases and that the ossification of pubic points increased to be always visible from 27 weeks of gestation onward. Performed in a single center by a referring operator on 1,539 fetuses, the feasibility reached 94.74%. Both set of measurements were concordant (mean PD distance value of 5.42 ± 1.8 mm). Interestingly, all 23 fetuses with bladder exstrophy showed a significantly larger PD distance (mean 15.74 ± 3.9 mm).

CONCLUSION: PD measurement in the fetus is feasible and reliable in the second half of gestation and can be used to support the antenatal diagnosis of bladder exstrophy with PD values exceeding 10 mm.