First-trimester molecular diagnosis of complete hydatidiform mole associated with dizygotic twin pregnancy conceived by intrauterine insemination.

OBJECTIVE

To present first-trimester molecular diagnosis of complete hydatidiform mole (CHM) associated with dizygotic twin pregnancy conceived by intrauterine insemination.

MATERIALS AND METHODS

A 32-year-old woman presented to the hospital with a huge complex cystic mass measuring about 8.5 cm × 4.1 cm in the uterine cavity and a living co-existing fetus with fetal biometry equivalent to 9 weeks. She underwent chorionic villus sampling at 13 weeks of gestation, and microsatellite genotyping for molar pregnancy test was applied. A molar pregnancy test was performed by a short tandem repeat (STR) identifier polymerase chain reaction (PCR) polymorphic marker analysis. The pregnancy was terminated at 14 weeks of gestation. Postnatal polymorphic DNA marker analysis of the placenta by quantitative fluorescent PCR (QF-PCR) was performed. Analysis of maternal blood total β-human chorionic gonadotropin revealed a high level of 551,600 mIU/mL at 10 weeks of gestation and a level of 1.0 mIU/mL at 15 weeks postpartum. The woman was doing well at 4 months after delivery.

RESULTS

The results of STR identifier PCR polymorphic marker analysis showed androgenic conception in the complex cystic mass and biparental conception in the living fetus. Pathological analysis of the cystic mass confirmed the diagnosis of CHM. The results of QF-PCR showed biparental inheritance in the normal fetus and complete paternal homozygosity in the CHM of the abnormal fetus in all STRs, indicating dizygotic twinning and CHM of monospermy.

CONCLUSION

Prenatal sonographic diagnosis of placentomegaly with many grape-like vesicles should include a differential diagnosis of CHM, partial hydatidiform mole (PHM), placental mesenchymal dysplasia (PMD), and recurrent hydatidiform mole. Microsatellite genotyping for molar pregnancy testing and zygosity testing is useful in cases of prenatal diagnosis of placentomegaly associated with many grape-like vesicles and a twin pregnancy with a living fetus in the first trimester.