[Massive subchorial thrombosis].

Massive subchorial thrombosis (MSCT) is a placental abnormality, the etiology and pathogenesis of which remain inadequately studied. MSCT is characterized by a clinical symptom complex comprising marked intrauterine growth retardation, oligohydramnios, and fetal distress due to placental circulatory problems. Perinatal outcomes are appreciably determined by the term of pregnancy, the degree of placental insufficiency, and neonatal status. Prolonged MSCT makes it possible to diagnose this pathology by echographic and magnetic resonance imaging studies and to attempt to treat placental dysfunction through tocolytic therapy and correction of oligohydramnios, to prolong pregnancy, and to have a viable newborn infant. The clinical and morphological diagnosis of MSCT calls for its differential diagnosis with other focal placental lesions, such as subamniotic, intraplacental, and retroplacental hematomas, cytotrophoblastic cyst, umbilical cord cysts, and chorangioma.