Prenatal diagnosis and outcome of subamniotic hematomas

Abstract

Subamniotic hematomas are classical placental pathological lesions resulting from the rupture of chorionic vessels near the cord insertion. Most subamniotic hematomas are found after birth and result from excessive traction on the umbilical cord at delivery. The development of these lesions has been rarely reported in utero. We report here five cases of subamniotic hematomas diagnosed by ultrasound between 18 and 30 weeks of gestation. The sonographic features were those of a poorly reflective oval-shaped cystic mass overlying the fetal plate of the placenta and covered in a thin membrane. In all the cases, a cystic structure containing a thrombotic mass arising from the amniotic membrane, which was attached to the fetal placental surface, was found after delivery. A high maternal serum alpha-fetoprotein level was found retrospectively in the four cases for which this information was available. Two pregnancies were complicated by slow fetal growth, one by vaginal bleeding and one by polyhydramnios. These findings demonstrated that subamniotic hematoma can be accurately diagnosed in utero by ultrasound and differentiated from other lesions of the placental chorionic plate. The findings also show that, although the lesion is located between the chorion and the amnion, it can be associated with fetomaternal hemorrhage and with fetal growth restriction.

Prenatal Diagnosis of a Subamniotic Hematoma

“…Deans and Jauniaux [2] report high MSAFP at 15-18 weeks (ranging from 4.9 to 10.2 MoM), whereas our case had a normal MSAFP of 1.4 MoM at 16 weeks of gestation. This could be explained by the time of occurrence of the hemorrhage: the present case was diagnosed at 33 weeks of gestation, and most probably occurred after 30 weeks, whereas the average gestational age at diagnosis in the series of Deans and Jauniaux [2] was 22.5 (range 18-30) weeks.…”

“…This could be explained by the time of occurrence of the hemorrhage: the present case was diagnosed at 33 weeks of gestation, and most probably occurred after 30 weeks, whereas the average gestational age at diagnosis in the series of Deans and Jauniaux [2] was 22.5 (range 18-30) weeks. The rise in MSAFP may be caused by extravasation of fetal blood into the maternal circulation.…”

“…Color Doppler examination showed the absence of flow within the mass, as well as in the surrounding membrane. The size of maximal diameter of the reported cases ranged from 5 to 9 cm [2].…”

“…The differential diagnosis has to be considered with placental anomalies [1,2] (avillous spaces or 'placental lakes' [3,4], true placental cyst or cytotrophoblast cyst [5], circumvallate placenta, subchorionic hematomas or thrombi [6][7][8], chorangioma [6], Breus' mole [7], and infarction [9,10]), a cord cyst, and fetal anomalies ('vanishing twin', meningocele). Exact sonographic localization, shape and echogenicity of the lesion over time [1] and Doppler flow examination enable differentiation between a subamniotic hematoma and other lesions.…”

Subamniotic Haematoma Associated with an Uneventful Labour

“…2 As such, the placenta in the present case was sent for histopathological examination to assess the solid mass of the placenta and to exclude rare placental neoplasms, such as a chorioangioma. 4 Placental infarctions may also be related to gestational diabetes.…”