[Massive perivillous fibrin deposition in twin placentas: a clinicopathological analysis of eleven cases].

Objective: To investigate the clinical and pathological characteristics of massive perivillous fibrin deposition (MPFD) in twin placentas. Methods: A retrospective analysis was performed on 11 cases of MPFD in twin pregnancies diagnosed at the Obstetrics and Gynecology Hospital Affiliated to Fudan University between January 2018 and December 2024. Maternal and fetal clinical features, as well as placental pathological findings, were summarized. Results: MPFD cases accounted for 2.8% (11/390) of all twin placentas submitted for pathological examination during the study period. Clinical analysis revealed that 6/11 cases were conceived via in vitro fertilization-embryo transfer; 10/11 women had a history of spontaneous abortion, with 3/11 meeting the criteria for adverse obstetric history (≥3 spontaneous abortions or perinatal deaths). Prenatal abnormalities in fetuses primarily included intrauterine growth restriction, intrauterine distress, and intrauterine death. Placental pathological examination showed generally low placental weight, advanced maturation in most cases, and more than 25% of villi surrounded by abundant amorphous eosinophilic fibrinoid material, leading to complete obstruction of the intervillous spaces. In one case of recurrent MPFD, only one placenta in a dichorionic diamniotic twin pregnancy was affected, with the corresponding fetus exhibiting intrauterine growth restriction. The rate of adverse obstetric outcomes was 10/11, including miscarriage (3/11), single or twin intrauterine death (3/11), and preterm birth (5/11). Follow-up for over 4-72 months indicated that one case was lost to follow-up, while the remaining mothers recovered well and live-born infants demonstrated normal development. Conclusions: MPFD can occur in twin pregnancies and may manifest as discordant involvement between co-twins, primarily presenting as adverse pregnancy outcomes such as fetal growth restriction. MPFD has a tendency for recurrence, and clinicians should remain vigilant for its consequence in high-risk twin pregnancies. Placental pathological examination plays a critical role in confirming diagnosis and guiding subsequent pregnancy management.