Miscarriage risk is not increased with subchorionic hematoma

Major finding: Subchorionic hematoma shows no statistically significant association with pregnancy outcomes at the end of the first trimester or final pregnancy outcomes.

Data source: Prospective observational study of 1,115 women, 142 of whom had a subchorionic hematoma.

Disclosures: No relevant financial conflicts of interest were declared.



SYDNEY – The presence of subchorionic bleeding around the gestational sac does not appear to increase the risk of miscarriage, according to data from a prospective observational study.

In a study of 1,115 women in early pregnancy, 142 (13%) had documented subchorionic hematoma. The women were diagnosed either after presenting with bleeding or during a routine dating scan. Researchers looked at the outcomes of pregnancy in both groups at the end of the first trimester and the final pregnancy outcome. They found no statistically significant association between the presence of subchorionic bleeding and miscarriage, according to findings presented at the International Society on Ultrasound in Obstetrics and Gynecology world congress.

Dr. Nicole Stamatopoulos

Lead author Dr. Nicole Stamatopoulos said the study came about because she observed a significant number of women attending the unit with subchorionic hematoma.

Looking at viable pregnancies that later miscarry, "we wondered if the bleeding around the gestational sac was one of the reasons why these women were miscarrying," said Dr. Stamatopoulos, a researcher at Nepean Hospital in Penrith, Sydney.

Dr. Stamatopoulos said that a diagnosis of subchorionic hematoma – which is one of the most common sonographic abnormalities with live embryos – often caused women a lot of concern, particularly when it was accompanied by vaginal bleeding.

She said the findings should offer some reassurance to these women.

"If you’ve got an embryo that’s got a heart rate, and someone’s come in with bleeding, and there is a subchorionic hematoma, I think you can reassure those women," Dr. Stamatopoulos said in an interview.

However, she said that reassurance could not necessarily be extended to women in whom a viable pregnancy was yet to be established.

The causes of subchorionic hematoma are not well understood, but the condition may result from trauma or may be related to the process of the trophoblast embedding into the uterus, Dr. Stamatopoulos said.

The next step in the study is to explore a possible relationship between the size of the hematoma and pregnancy outcomes.

"I’ve got data relating to the actual size of the subchorionic hematoma, to see whether or not, if it’s a really large one, does that increase the risk of miscarriage? Or if it’s just small, is it not a problem?" she said.

There were no relevant financial conflicts of interest declared.

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