Subchorionic Hematoma

Overview

A subchorionic hematoma is a buildup of blood between the chorion (the outer membrane that surrounds the embryo) and the wall of the uterus. It happens when this membrane partly separates from the uterine lining and a small amount of blood pools in the space created. It is one of the most common findings linked to bleeding in early pregnancy.

Many subchorionic hematomas cause no symptoms and are noticed only when an ultrasound is done for another reason. Others lead to light spotting or bleeding. While any bleeding in pregnancy can be frightening, most small subchorionic hematomas reabsorb on their own and the pregnancy continues normally.

Symptoms

Symptoms depend on the size and location of the blood collection. Common experiences include:

• Light vaginal bleeding or brown spotting, sometimes on and off
• Mild cramping or a feeling of pelvic heaviness
• No symptoms at all, with the hematoma found on ultrasound

Bright red, heavy bleeding, the passage of clots or tissue, severe cramping, or feeling faint are not typical of a small hematoma and should be evaluated promptly, as they can signal a larger bleed or another problem.

Causes

A subchorionic hematoma forms when the membranes surrounding the pregnancy partially detach from the uterine wall, allowing blood to collect in the gap. In most cases the exact reason this happens is not known, and it is not caused by anything the pregnant person did.

It is not the same as a placental abruption, which involves separation of an established placenta later in pregnancy, although the two can be confused on imaging. The bleeding usually comes from small vessels at the edge of the developing placenta or membranes.

Risk Factors

Subchorionic hematomas can occur in any pregnancy, but some factors are seen more often:

• Pregnancy conceived through assisted reproductive technology such as IVF
• History of recurrent pregnancy loss
• Uterine abnormalities or fibroids
• Use of certain blood-thinning medications
• Older maternal age

In many people, none of these factors are present.

Diagnosis

The diagnosis is made by ultrasound, which can show the crescent-shaped pocket of blood next to the gestational sac and estimate its size relative to the sac. A pelvic exam may be done to check the source of any bleeding and confirm the cervix is closed.

• Transvaginal or abdominal ultrasound: Confirms the hematoma, measures it, and checks the embryo's heartbeat.
• Repeat scans: Used to follow whether the collection is shrinking, stable, or growing.
• Blood tests: Pregnancy hormone (hCG) levels and blood count may be checked if bleeding is significant.

Treatment

There is no specific medication that dissolves a subchorionic hematoma, and most resolve without treatment as the body gradually reabsorbs the blood. Management focuses on monitoring and supportive measures:

• Watchful waiting with follow-up ultrasounds to confirm the hematoma is improving and the pregnancy is progressing.
• Activity adjustment: Some clinicians advise reducing strenuous activity or avoiding intercourse while bleeding is present, though evidence that rest changes outcomes is limited.
• Treating heavy bleeding: Rarely, a large bleed needs closer hospital monitoring.

Always follow the specific advice of your own pregnancy care provider, who can tailor recommendations to your situation.

Prevention

Because the cause is usually unknown, there is no proven way to prevent a subchorionic hematoma. General steps that support a healthy early pregnancy include attending prenatal appointments, taking recommended prenatal vitamins, and reporting any bleeding to your provider so it can be evaluated. If you take blood thinners, do not stop or change them without medical advice.

When to See a Doctor

Report any vaginal bleeding during pregnancy to your provider so it can be checked. Seek urgent or emergency care if you have:

• Heavy bleeding that soaks through a pad in an hour, or passing large clots or tissue
• Severe or worsening abdominal or pelvic pain
• Dizziness, fainting, or a racing heartbeat
• Fever or chills along with bleeding

These can indicate a larger bleed, miscarriage, or another condition that needs prompt attention.

Related Topics

Frequently Asked Questions

References

1. MedlinePlus, U.S. National Library of Medicine. Bleeding during pregnancy.
2. American College of Obstetricians and Gynecologists (ACOG). Early Pregnancy Loss.
3. StatPearls, National Library of Medicine. Subchorionic Hemorrhage.
4. Mayo Clinic. Bleeding during pregnancy.