Subchorionic Hematoma: What It Is, Causes & Pregnancy Risk

A subchorionic hematoma is a condition where there is abnormal blood accumulation between the uterine wall and the chorionic membrane. It is one of the many underlying causes that may lead to vaginal bleeding during pregnancy. Vagina bleeding at any stage in pregnancy needs immediate medical assessment. In this post, we explain the causes, symptoms, diagnosis, side effects, and treatment of subchorionic hematoma.

What Is Subchorionic Hematoma?

Subchorionic hematoma (SCH), also termed as subchorionic hemorrhage, is a condition wherein the blood collects/clots between the uterine wall and the chorionic membrane (1). The chorion is the outer membrane between the uterus and placenta, and surrounds the amniotic sac (2).

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The hematoma leads to placental detachment from the chorion membrane, causing subchorionic bleeding. Around 25% of pregnant women experience subchorionic bleeding during the first trimester (3).

How Common Is Subchorionic Hematoma?

Around 5-25% of pregnant women experience subchorionic hematoma during pregnancy. Vaginal bleeding complicates around 20-25% of all pregnancies, and nearly 20% of pregnant women who visit a hospital with vaginal bleeding are diagnosed with SCH.

Let’s see what leads to SCH and vaginal bleeding.

What Are The Causes Of Subchorionic Hematoma?

The exact cause of SCH is not yet known. It is assumed to be the result of a preexisting autoimmune disease or immunological factors (4).

Another probable reason is poor placentation, which results in weak vessels that could tear under pressure and lead to low pressure bleeding (5). This condition occurs when the placenta detaches from its plantation site, causing the blood to flow into the chorionic membrane. Thus, a blood clot is formed in the space between the uterus and the placenta (6).

The other causes could be:

• Abnormal implantation of the fertilized egg in the uterus
• More in pregnancy conceived via IVF or frozen thawed embryo transfer

• Trauma

• Blood coagulation disorders

• Scars from previous dilatation and curettage

• Mother’s age is more than 35 years

• Uterine malformation

• Infection

The condition could go unnoticed but for vaginal bleeding.

What Are the Symptoms Of Subchorionic Hematoma?

One of the most common symptoms of subchorionic hematoma is vaginal bleeding. It can be either in the form of spotting or heavy bleeding. The bleeding may come along with severe abdominal pain or dizziness and cramping.

However, you may not know the reason behind the vaginal bleeding as hematoma can only be detected in an ultrasound scan.

How Is Subchorionic Hematoma Diagnosed?

The only way to detect subchorionic hematoma is through an ultrasound. Depending on the intensity of vaginal bleeding, the doctor may use abdominal or transvaginal ultrasound to determine the reason for the bleeding (7).

An ultrasound can detect the blood clots between the uterus and placenta. The transvaginal method aids in examining the uterine area through the vagina.

Once the scan confirms SCH, the doctor will determine the size of the hemorrhage as the size reflects the intensity of the problem.

Size Of Subchorionic Hematoma

The size of SCH is evaluated (8) depending on the elevation of the chorionic membrane from the uterus wall.

Typically, if the size of the hematoma is 50-66% of the gestational sac then it is large, and less than 20% of the sac is considered small (1). A large hematoma increases the chance of spontaneous abortion, but a small sized one is common during the first trimester.

Is Subchorionic Hematoma Harmful?

Smaller hematomas do not harm your pregnancy but result in bleeding. However, larger hematomas carry some serious pregnancy risks such as preterm labor and placental abruption (9). The risks of subchorionic hematoma are:

• Subchorionic hematoma increases the risk of miscarriage in the first 20 weeks of pregnancy. However, vaginal bleeding in an ongoing pregnancy will not increase the chance of a miscarriage (10).

• SCH, in combination with any underlying pregnancy complication such as stress or injuries, also increases the chances of miscarriage (11).

• The outcome of the pregnancy with subchorionic hematoma depends on the size of hematoma, gestational age, and the mother’s age. (12).

• The other risks associated with SCH include intrauterine growth restriction, pre-eclampsia, placental abruption or oligohydramnios.

Depending on the size of the hematoma, your doctor would suggest the course of treatment.

How Is Subchorionic Hematoma Treated?

Here is what your doctor might do/advice to treat this condition:

• The doctor may order bed rest or advise you to minimize your activities if the hematoma size is small.

• You may need to avoid sexual intercourse during this period.

• The doctor may use estrogen or progesterone therapy to strengthen your pregnancy. Dydrogesterone is a synthetic progesterone hormone that is administered orally (40mg/day) for treating subchorionic bleeding (13).

• Blood thinners (anticoagulants) (14) may be advised to aid the removal of the blood clot.

• Your doctor would closely monitor your health for fetal and uterine health.

You may support SCH treatment with some personal care.

Managing Subchorionic Hematoma

Here are some ways to deal with this pregnancy condition:

• Keep track of any vaginal bleeding during pregnancy.
• Avoid heavy work and exercise.
• Stay well hydrated to prevent constipation and straining at stool.
• Take regular small meals with fiber.
• Stay calm and stress-free.
• Don’t miss any appointments with your doctor. Follow the doctor’s guidelines about bed rest and activity levels.

Read on as we answer some commonly asked questions on SCH.

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Dr. Monica Agarwal

(MD)

Dr. Monica Agarwal has 15 years of experience as a senior resident doctor at various medical institutions. She currently works as a senior consultant at Paras Bliss Hospital, Panchkula. Previously she taught at Gian Sagar Medical College and was a specialist in charge of the gynecology department at ESI Hospital, Ramdarbar, Chandigarh. Dr. Agarwal is a member of Medical Council... more

shreeja pillai

Shreeja holds a postgraduate degree in Chemistry and diploma in Drug Regulatory Affairs. Before joining MomJunction, she worked as a research analyst with a leading multinational pharmaceutical company. Her interest in the field of medical research has developed her passion for writing research-based articles. As a writer, she aims at providing informative articles on health and pharma, especially related to... more