Evaluation of the risk of persistent trophoblastic disease after twin pregnancy with diploid hydatidiform mole and coexisting normal fetus

Objective: This study was undertaken to evaluate the risk of persistent trophoblastic disease and obstetric complications related to a multiple pregnancy comprising a diploid hydatidiform mole and normal cofetus(es). Study Design: From a database of 270 consecutively collected hydatidiform moles, 8 multiple and 154 singleton molar pregnancies were identified. Molar and fetal ploidy was determined, and data on clinical features and chemotherapy were collected. Differences between groups were assessed with Fisher's exact or Mann-Whitney test. Results: The molar component in all 8 multiple pregnancies was diploid. Five patients with diploid mole and coexisting fetus pregnancy chose to terminate their pregnancy, 2 aborted spontaneously, and 1 patient delivered a healthy child. Two diploid mole and coexisting fetus pregnancies (25%) and 17% of the singleton molar pregnancies were followed by persistent trophoblastic disease (P = .63). Conclusion: The risk of persistent trophoblastic disease after a diploid mole with coexisting fetus pregnancy is similar to that after a singleton molar pregnancy, and expectant management instead of therapeutic abortion can be pursued.