Partial molar pregnancy with a viable co-twin complicated by placenta accreta spectrum: case report.

Introduction and importance: Twin pregnancies complicated by hydatidiform mole with a coexisting fetus (HMCF) and placenta accreta spectrum (PAS) are exceptionally rare and clinically challenging. Partial HMCF is particularly uncommon, with both conditions posing risks of hemorrhage, preeclampsia, and progression to gestational trophoblastic neoplasia. Case presentation: A 32-year-old gravida 4, para 3 woman with a history of three prior cesarean sections presented at 24 + 3 weeks with vaginal bleeding, headache, and blurred vision. Ultrasound revealed a dichorionic twin pregnancy: one partial molar placenta and another with placenta previa suspicious for PAS. The course was complicated by preeclampsia features and suspected thyroid storm. Spontaneous preterm delivery was followed by massive postpartum hemorrhage requiring emergency hysterectomy. Histopathology confirmed partial mole and PAS (Grade III). Recovery was uneventful, with complete beta-human chorionic gonadotropin remission. Clinical discussion: This case highlights the compounded risks of overlapping placental pathology in multiple gestations, emphasizing diagnostic challenges and the need for vigilant surveillance. Conclusion: Coexistence of partial mole and PAS in twin pregnancy is rare and high-risk. Prior cesarean history may contribute to PAS development, underscoring the importance of multidisciplinary management and individualized delivery planning.