Massive multicystic dilatation of the uterine wall with myometrial venous thrombosis during pregnancy.

We present a pregnancy complicated by multicystic dilatation of the uterine wall during the second trimester, leading to massive uterine distension, anemia and preterm Cesarean section. The cystic changes detected by ultrasound and magnetic resonance imaging involved the whole uterine wall surrounding the entire amniotic cavity. Histopathological examination revealed the benign nature of the cystic changes, which represented dilated and thrombosed venous lacunae. Disturbed venous drainage, combined with local thrombosis, was likely to have led to the collection of a large volume of blood in the uterine wall and the subsequent multicystic change of the myometrium.