Twin molar pregnancy: a diagnostic framework for early recognition and appropriate management

Twin molar pregnancy (TMP) represents one of the most complex and high-risk entities within the spectrum of gestational trophoblastic disease. Characterized by the coexistence of a potentially viable fetus and molar trophoblastic tissue, TMP poses significant diagnostic, obstetric, and oncologic challenges.

To provide a structured diagnostic and management framework for TMP, integrating clinical, biochemical, imaging, genetic, and pathological findings to support early recognition and informed clinical decision-making.

This narrative review synthesizes contemporary evidence from cohort studies and diagnostic guidelines, focusing on the clinical presentation, imaging characteristics, genetic evaluation, and outcomes associated with TMP.

Early diagnosis is frequently hindered by overlapping features with partial hydatidiform mole and placental mesenchymal dysplasia, particularly as placental components merge with advancing gestation. Common clinical manifestations include vaginal bleeding, uterine enlargement disproportionate to gestational age, and systemic complications related to markedly elevated human chorionic gonadotropin levels, such as early-onset preeclampsia, hyperthyroidism, and theca lutein cysts. Ultrasonography remains the primary diagnostic modality, while magnetic resonance imaging provides additional value in complex cases. Genetic testing, including invasive fetal karyotyping and post-pregnancy molecular analysis, is essential for accurate classification and counseling. Management should be individualized, prioritizing maternal safety while recognizing the potential for favorable perinatal outcomes in selected cases. Current evidence suggests that continuation of pregnancy does not independently increase the risk of postmolar gestational trophoblastic neoplasia, which appears to be primarily driven by intrinsic trophoblastic biology.

TMP remains a rare but clinically challenging condition requiring a high index of suspicion and a multidisciplinary approach. Early diagnosis, individualized management, and rigorous postmolar surveillance are essential to optimize maternal and perinatal outcomes.