Chorionic hematoma is the pooling of blood (

hematoma A hematoma, also spelled haematoma, or blood suffusion is a localized bleeding outside of blood vessels, due to either disease or trauma including injury or surgery and may involve blood continuing to seep from broken capillaries. A hematoma is ...

) between the

chorion The chorion is the outermost fetal membrane around the embryo in mammals, birds and reptiles ( amniotes). It develops from an outer fold on the surface of the yolk sac, which lies outside the zona pellucida (in mammals), known as the vitellin ...

, a membrane surrounding the

embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...

, and the uterine wall.Nagy, Sándor MD; Bush, Melissa MD; Stone, Joanne MD; Lapinski, Robert H. PhD; Gardó, Sándor MD, DSci. ''Clinical Significance of Subchorionic and Retroplacental Hematomas Detected in the First Trimester of Pregnancy'

Obstetrics & Gynecology: July 2003 - Volume 102 - Issue 1 - p 94-100 It occurs in about 3.1% of all pregnancy, pregnancies, it is the most common sonographic abnormality and the most common cause of first trimester bleeding.Avneesh Chhabra, MD et al. "Subchorionic Hemorrhage

Medscape.

Cause and diagnosis

Chorionic hematomas can be caused by the separation of the chorion from the

endometrium The endometrium is the inner epithelial layer, along with its mucous membrane, of the mammalian uterus. It has a basal layer and a functional layer: the basal layer contains stem cells which regenerate the functional layer. The functional lay ...

(inner membrane of the uterus). Hematomas are classified by their location between tissue layers: * Subchorionic hematomas, the most common type, are between the chorion and endometrium. * Retroplacental hematomas are entirely behind the placenta and not touching the gestational sac. * Subamniotic or preplacental hematomas are contained within amnion and chorion. Rare. Most patients with a small subchorionic hematoma are asymptomatic. Symptoms include

vaginal bleeding Vaginal bleeding is any expulsion of blood from the vagina. This bleeding may originate from the uterus, vaginal wall, or cervix. Generally, it is either part of a normal menstrual cycle or is caused by hormonal or other problems of the reproducti ...

abdominal pain Abdominal pain, also known as a stomach ache, is a symptom associated with both non-serious and serious medical issues. Common causes of pain in the abdomen include gastroenteritis and irritable bowel syndrome. About 15% of people have a m ...

premature labor Preterm birth, also known as premature birth, is the birth of a baby at fewer than 37 weeks gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 weeks, very early preterm birth is between ...

and threatened miscarriage.

Ultrasonography Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies f ...

is the preferred method of diagnosis. A chorionic hematoma appears on ultrasound as a hypoechoic crescent adjacent to the

gestational sac The gestational sac is the large cavity of fluid surrounding the embryo. During early embryogenesis it consists of the extraembryonic coelom, also called the chorionic cavity. The gestational sac is normally contained within the uterus. It is the o ...

. The hematoma is considered small if it is under 20% of the size of the sac and large if it is over 50%.

Prognosis and treatment

The presence of subchorionic bleeding around the gestational sac does not have a significant association with miscarriage overall. However, the case of intrauterine hematoma observed before 9 weeks of

gestational age In obstetrics, gestational age is a measure of the age of a pregnancy which is taken from the beginning of the woman's last menstrual period (LMP), or the corresponding age of the gestation as estimated by a more accurate method if available. Su ...

has been associated with an increased risk of miscarriage. In one study women who complied with instructions for bed rest for the duration of bleeding had a lower rate of miscarriage and a higher rate of term pregnancy than non-compliant women. The study had several limitations; results were severely confounded by inherent differences between compliant and non-compliant women.Ben-Haroush A, Yogev Y, Mashiach R, Meizner I. ''Pregnancy outcome of threatened abortion with subchorionic hematoma: possible benefit of bed-rest?'' Journal Isr Med Assoc J. 2003 Jun;5(6):422-4

References

{{Pathology of pregnancy, childbirth and the puerperium Health issues in pregnancy