What Is a Subchorionic Hematoma?

Any type of bleeding during pregnancy can be alarming. However, not all bleeding during pregnancy means there's a problem. About 25% of women experience some bleeding or spotting during their pregnancy. 

Subchorionic hematomas are the cause of about 20% of all bleeding during the first trimester. This is a type of bleeding that occurs between your amniotic membrane, which is the membrane that surrounds your baby, and your uterine wall. It occurs when the placenta partially detaches from where it was implanted in the wall of your uterus.

Subchorionic hematomas can be small or large. Small ones are more common. Larger ones tend to cause more bleeding and problems. 

What Causes a Subchorionic Hematoma?

The specific causes of subchorionic hematoma aren't clear. There are some risk factors associated with them, including: 

  • Malformation of the uterus
  • History of recurrent miscarriages
  • History of pelvic infections
  • Trauma
  • Early-onset preeclampsia, which is a serious pregnancy complication marked by high blood pressure and organ failure
  • Severe high blood pressure
  • In vitro fertilization 

What Are the Symptoms of a Subchorionic Hematoma?

For most women, bleeding or cramping is the only symptom of a subchorionic hematoma. Sometimes there are no symptoms, and it is discovered during an ultrasound. 

How Is a Subchorionic Hematoma Treated?

The treatment for a subchorionic hematoma will depend on several factors. These include how far along you are in your pregnancy and the size of your hematoma. 

Before 20 weeks' gestation. If you have a subchorionic hematoma found before you're 20 weeks along in your pregnancy, your doctor is likely to recommend that you reduce your activity levels. They might also suggest that you limit any travel. Your doctor will likely recommend hospitalization if any bleeding, cramping, or contractions occur. 

After 20 weeks' gestation. If you have a subchorionic hematoma that is found after you're 20 weeks pregnant, your doctor will teach you the signs and symptoms of early labor. Your treatment may include: 

  • A RhoGAM, if you are Rh-negative and your baby is Rh-positive
  • Sonograms about once a month to check your baby's growth, possibly more frequently
  • Preterm labor treatment if you start having contractions
  • Hospitalization, especially if bleeding occurs after 24 weeks 

Continued

Will a Subchorionic Hematoma Harm My Baby?

Many women with subchorionic hematomas have healthy pregnancies and deliveries. Small and moderate hematomas often go away on their own.   Larger hematomas are more likely to cause problems.

There is a higher risk if the subchorionic hematoma is detected in the first 20 weeks of your pregnancy. You should seek treatment as soon as possible for the best possible outcome. 

What Are Other Causes of Bleeding in Pregnancy?

Subchorionic hematomas are only one cause of bleeding during pregnancy. There are other causes of bleeding that range from harmless to dangerous. You should always talk to your healthcare provider if you experience any vaginal bleeding during pregnancy. 

Cervical changes. Pregnancy causes changes to the cervix that can result in bleeding. You may bleed after having sex, for instance. 

Implantation bleeding. Early in your pregnancy, you may experience light spotting. This happens when your baby implants into the wall of your uterus. It usually occurs around the time you would normally have your period. 

Ectopic pregnancy . This occurs when the egg implants outside of your uterus, such as in the fallopian tubes. This is a dangerous condition that requires immediate treatment. Other symptoms of ectopic pregnancy can include: 

  • Stomach pain low on one side
  • Vaginal bleeding
  • Brown, watery discharge
  • Pain in the tip of your shoulder
  • Discomfort with urination or elimination 

Miscarriage . Most miscarriages occur in the first 12 weeks of pregnancy. Some symptoms of miscarriage include: 

  • Pain and cramping in your lower abdomen
  • Vaginal discharge or fluid
  • Discharge of tissue from your vagina
  • No longer experiencing symptoms of early pregnancy, such as nausea or breast tenderness

Vaginal infections. These can be diagnosed and treated by your healthcare provider.

Bloody show. This is when the plug of mucus that has been in your cervix falls out. This usually happens at the beginning of labor. It can happen a few days before contractions start or during labor. 

Placenta previa. This is when you have a low-lying placenta near or over your cervix. You may need to go to the hospital for emergency treatment. 

To discover the cause of your bleeding, your doctor will discuss your symptoms with you and may do a physical exam. You may also need to have an ultrasound or blood work done.  

WebMD Medical Reference Reviewed by Dan Brennan, MD on March 09, 2021

Sources

SOURCES: 

March of Dimes: "BLEEDING AND SPOTTING FROM THE VAGINA DURING PREGNANCY."

NHS: "Vaginal bleeding."

Obstetrics & Gynecology: "Association Between First-Trimester Subchorionic Hematomas and Pregnancy Loss in Singleton Pregnancies."

Journal Of The Turkish-German Gynecological Association: "The effects of subchorionic hematoma on pregnancy outcome in patients with threatened abortion."

Radiology: "Placental abruption and subchorionic hemorrhage in the first half of pregnancy: US appearance and clinical outcome."

San Diego Perinatal Center: "Subchorionic Hematoma."

StatPearls: "Subchorionic Hemorrhage."

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