Updated December 10, 2014.

When your doctor first says the words "subchorionic hematoma," your first response might be to panic -- perhaps even more so if you hear the scarier sounding version "subchorionic hemorrhage." (The two are synonyms.) But although finding out you have a subchorionic hematoma is not great news, it doesn't always mean you're destined for an unhappy outcome -- and many pregnancies affected by subchorionic hematoma turn out fine.

Here's what you need to know.

What a Subchorionic Hematoma Is:

A subchorionic hematoma is a type of blood clot found between the pregnancy membranes and the wall of the uterus. This occurs in just over 1% of pregnancies, and it appears that the bleeding occurs when small parts of the pregnancy membranes separate from the uterus. There is no evidence that this happens because of anything the mother did; doctors don't really know why it occurs.

Signs of Subchorionic Hematoma:

A woman with a subchorionic hematoma can have bleeding of varying quantities, ranging from light spotting to a heavy flow with clots, or she may have no outward symptoms at all. The bleeding can be painless, or there may be mild abdominal cramping.

Diagnosis:

Doctors use ultrasound to diagnose subchorionic hematoma. If the woman is having vaginal bleeding leading up to the diagnosis, she may also receive a diagnosis of threatened miscarriage. Again, threatened miscarriage sounds scary, but usually the majority of women diagnosed with threatened miscarriage will go on to have viable pregnancies.

Risk of Complications:

A subchorionic hematoma increases the risk of miscarriage in some cases. Studies have found that the risk of miscarriage may be higher if the hematoma is diagnosed early in the first trimester or if it has a larger size. Smaller-sized hematomas usually do not affect the pregnancy. Larger-sized hematomas can also increase the risk of other pregnancy complications, such as growth restriction or preterm labor.

Dealing with the Diagnosis:

There is probably nothing worse than knowing something might be threatening your baby and that you don't have the power to fix it. It's natural that you might feel anxious and unable to focus on anything else. But remember that there is a good chance that everything will turn out okay, especially if the hematoma is small. In fact, the odds of a positive outcome are usually much higher than the odds of losing the baby -- so there is every reason to think positively.

Of course, that may not ease your worries. So in this stressful time, the best you can do is follow your doctor's recommendations and try to find ways to keep your mind occupied. If your doctor has recommended bed rest, rent some really great movies or have your partner pick up a stack of new novels for you to read. Keep in touch with your doctor on when you need to come in for a followup, at which point you should hopefully get more information on how things are progressing.

<sub>Sources:

Bennett, G.Ll, B. Bromley, E. Lieberman, and B.R. Benacerraf, "Subchorionic hemorrhage in first-trimester pregnancies: Prediction of pregnancy outcome with sonography." Radiology 1996. Accessed 17 Nov 2008.

Cagsar, Esen, Hakan Kanit, Dilek Aslan, and Julide Duran, "Significance of Subchorionic Hematomas in Patients with Threatened Abortion: A Sonographic Study." Perinatoloji Dergisi 2001. Accessed 17 Nov 2008.

Chhabra, Avneesh, "Subchorionic Hemorrhage." eMedicine. Jul 2008. Accessed 17 Nov 2008.

Maso, Gianpaolo, Giuseppina D'Ottavio, Francesco De Seta, Andrea Sartore, Monica Piccoli, and Giampaolo Mandruzzato, "First-Trimester Intrauterine Hematoma and Outcome of Pregnancy." Obstetrics & Gynecology 2005. Accessed 17 Nov 2008.</sub>