Prenatal diagnosis of fetal genital prolapse

Abstract

Neonatal genital prolapse, an uncommon condition,usually presents as a tumor-like mass protruding from theventralpartofthevulva.Allcasesthathadbeenpreviouslyreported were diagnosed after birth. We present thefirst case report of fetal genital prolapse that presentedprenatally by ultrasonography as a solid protruding lesionon the ventral part of the vulva. Postnatal magneticresonance imaging (MRI) confirmed the diagnosis ofan isolated neonatal vaginal prolapse. At follow-upexamination at 6 months of age, the infant’s externalgenitalia appeared normal, with no evidence of genitalprolapse.A 33-year-old woman, gravida 2 para 1, attended ourprenatal care clinic at 12 weeks’ gestation to request first-trimester ultrasound screening to evaluate the risk offetal Down syndrome. Ultrasound examination revealedan increased nuchal translucency thickness of 3 mm.After genetic counseling, chorionic villus sampling wasperformed uneventfully; testing revealed a normal femalekaryotype (46,XX). The patient presented at 20 weeks’gestation to complain that an error had been made inthe ultrasonographic fetal gender deduced at a localobstetric clinic. Consequently, we performed a detailedfetal sonographic examination, which found a phallus-like structure protruding over the ventral part of thefetal vulva (Figure 1). The covering of the protrudingmass was continuous with the lining of the vaginal wall(Figure 2). Fetal growth was appropriate for gestationalage, but the amniotic fluid index was 29.2 cm, indicatingpolyhydramnios. Fetal ambiguous genitalia or genitalprolapse were suspected.Sex-determining region Y gene analysis was negativeafter a follow-up amniocentesis was done to providerapid fetal sex determination (ruling out an XX maleor maternal cell contamination) and ensure that noerror had occurred in the original fetal karyotyping.Androgen levels were measured in maternal blood andfound to be normal. Both parents were negative forthe carrier test for the CYP21 gene. A diagnosis offetal genital prolapse was finally made. The parentswere made aware of the implications of the diagnosisand made a fully informed choice to continue thepregnancy.At 33 weeks of gestation, the patient was admitted withpreterm rupture of membranes and emergency Cesareansection ensued owing to breech presentation. At birth,the baby weighed 2080 g and had a mass protrudingbetweentheinfantlabiaminora.Closeinspectionrevealedrugae consistent with vaginal epithelium (Figure 3). Anormal urethral orifice was confirmed and spontaneousvoiding was observed along with a normal outer analappearance with passage of meconium. The prolapsedlesion was reducible with a Q-tip. Two weeks later,transabdominalultrasonographydepictedanormalinfantuterus measuring 2