Can fetal ultrasound result in prenatal diagnosis of Prader-Willi syndrome?

OBJECTIVE

To define fetal ultrasound characteristics triggering an antenatal diagnosis of Prader Willi syndrome (PWS).

METHODS

Retrospective analysis of sonographic characteristics retrieved from obstetric ultrasound records. All children (n=11) had a postnatal genetically confirmed diagnosis of PWS.

RESULTS

All patients (n=11) showed at least one aspecific abnormality on prenatal ultrasound. Ten out of eleven (90.9 %) had decreased fetal movements, 7 (63.6%) presented in breech position, 7 (63.6%) had severe intra-uterine growth restriction (<5th centile) and 4 (36.4%) showed a polyhydramnios. Immobile flexed limbs and clenched hands were seen in one patient (9.1%). Severe growth restriction combined with polyhydramnios favors the diagnosis in 3/11 cases.

CONCLUSION

Prenatal sonographic phenotype of PWS includes decreased fetal movements, fetal malpresentation, severe intra-uterine growth restriction and polyhydramnios. These findings are not specific to PWS, but the combination of some of them (especially severe intra-uterine growth restriction and polyhydramnios) can prompt clinicians to perform invasive testing leading to a molecular cytogenomic diagnosis prenatally.