Subamniotic hematoma mimickıng the tumor of fetal membranes in a midtrimester twin pregnancy: A case report

Subamniotic hematoma formation is a pathophysiologic end point of placental abruption. Placental abruption itself usually happens in the third trimester, but it can take place any time after 20 weeks of gestation. We present a second trimester twin pregnancy admitted to our clinic with mild vaginal bleeding. Ultrasound examination revealed that two fetuses were alive and aged 23 and 24 weeks of gestation. A mass located on the fetal membranes separating the fetuses was observed to be freely floating by fetal movements. There was neither abdominal pain nor contractions on cardiotocography. Ultrasound examination and clinical evaluation made the hematoma diagnosis more unlikely since the hematomas are usually located by or under the placenta and adherent to decidual and myometrial structures and, clinical picture did not fulfil the placental abruption diagnostic criteria. The case was misdiagnosed as twin pregnancy complicated by a tumor of fetal membranes, another rare entity. But during clinical observation, uterine contractions and abdominal cramp like pain are developed, and pregnancy is terminated spontaneously by preterm labor. After the delivery of fetuses, placentas and fetal membranes expulsed spontaneously. Gross and microscopic examination revealed that previously defined mass lesion was a subamniotic hematoma. We would like to stress that when a mass lesion located on or between the membranes is detected subamniotic hematoma should be kept in mind in differential diagnosis.