[Subamniotic hematoma: 3D and color Doppler imaging in the differential diagnosis of placental masses and fetal outcome]

The aim of this study was to evaluate the role of 3D and color Doppler (CD) imaging in prenatal diagnosis and management of placental subamniotic hematoma and to speculate about the prenatal diagnosis of the solid and cystic placental masses protruding from the fetal surface of the placenta. Five pregnancies in which a large mass was seen protruding from the fetal surface of the placenta were studied in the period between January 2006 and January 2008. 3D and color flow imaging were settled in order to monitor the sonographic features of the mass during pregnancy, to evaluate the continuity of the solid portion of the mass with the fetal placental surface and to detect the blood flow signals within the mass. This study reports the clinical outcome and the histologic findings of five cases of subamniotic hematomas detected in the course of prenatal ultrasound examinations between January 2006 and January 2008. Sonographic features of the mass protruding from the chorionic plate show a consistence typical of a solid mass, in the recent subamniotic hematoma, or a predominantly cystic mass in the chronic subamniotic hematoma. Neither adverse clinical correlations nor structural nor chromosomal fetal abnormalities were found after delivery. The joint and the continuity of the solid portion of the mass with the fetal placental surface were correctly identified by prenatal ultrasound 3D examination. The CD imaging was conclusive in order to detect the absence of blood flow within the solid part of these masses. In conclusion prenatal sonographic features in recent subamniotic hematomas include the detection of a complex structure overlying the fetal plate of the placenta next to the cord insertion, covered by a thin membrane (the amnion), containing a predominantly solid mass arising from the chorionic plate. Differential diagnosis has to be done between recent subamniotic hematoma and placental chorioangioma by the use of color flow imaging: it displays blood flow within the mass in the case of chorioangioma, and conversely demonstrates the lack of color flow signals in the hematoma. The 3D imaging is conclusive in order to identify the continuity of the solid mass with the fetal placental surface. The chronic subamniotic hematomas are predominantly cystic structures in which there is a solid component attached to the fetal surface of placenta, representing a retracted clot and/or a fibrin deposit, underlying the hematoma. The main differential diagnosis in the case of a cystic mass overlying the fetal plate of the placenta, covered by a thin membrane, during the ultrasound examination, is between a placental cyst and a large pseudocysts of the umbilical cord at the placental insertion. In the case of a pseudocyst, the transonic formation is clear and lacks of a solid mass within. The correct differential diagnosis between subamniotic hematoma and the pseudocysts of the umbilical cord is required because of the association between chromosomal anomalies and pseudocysts.