Vaginal bleeding during early pregnancy can be concerning for expectant parents. It is common, affecting up to 25% of individuals in the first trimester, and understanding its potential causes is important. Bleeding can range from light spotting to a heavier flow, and identifying the reason behind it helps guide appropriate medical evaluation and management. This article explores two distinct causes of early pregnancy bleeding: subchorionic hematoma and miscarriage, outlining their characteristics and how they differ.
What is a Subchorionic Hematoma?
A subchorionic hematoma (SCH), also known as a subchorionic hemorrhage or chorionic hematoma, involves a collection of blood between the chorion and the uterine wall. The chorion is the outer membrane that surrounds the developing embryo and later forms part of the placenta. Blood accumulates when the chorion membrane partially detaches from the uterine wall.
SCHs are common, affecting approximately 3.1% to 25% of pregnancies, and are the most frequent sonographic abnormality and cause of first-trimester bleeding. While some individuals with a small SCH may not experience symptoms, the most common symptom is vaginal bleeding, which can vary from light spotting to heavy bleeding with clots. Pelvic cramping may accompany the bleeding, but it is not always present. Many subchorionic hematomas resolve without serious complications.
What is a Miscarriage?
A miscarriage, medically termed spontaneous abortion, refers to the natural loss of a pregnancy before 20 weeks of gestation. Miscarriage is common, with 10 to 20 out of every 100 known pregnancies ending this way. The majority of miscarriages occur during the first trimester, often due to genetic abnormalities in the embryo that prevent normal development.
Typical signs of miscarriage include vaginal bleeding, which can range from light to heavy and may contain blood clots or tissue. Bleeding is often accompanied by lower abdominal cramping or pain, similar to menstrual cramps or strong labor-like contractions. Other symptoms can include the passage of fluid from the vagina or a sudden loss of pregnancy symptoms like nausea or breast tenderness.
Key Differences in Bleeding and Symptoms
Distinguishing between subchorionic hematoma bleeding and miscarriage can be nuanced, as both present with vaginal bleeding in early pregnancy. Subchorionic hematoma bleeding is often light to moderate, with colors ranging from light pink to dark brown, reflecting older, pooled blood. Bleeding can be intermittent and may not consistently be accompanied by pain, though mild cramping can occur.
In contrast, miscarriage bleeding tends to be heavier and is frequently bright red, indicating more active bleeding. Bleeding often becomes progressively more intense and is typically accompanied by more significant cramping or abdominal pain, which can be persistent. The passage of tissue or clot-like material is a stronger indicator of miscarriage than subchorionic hematoma. While subchorionic hematoma bleeding can occur sporadically throughout the first trimester and often resolves, miscarriage bleeding commonly begins suddenly and increases rapidly in intensity as the body attempts to expel pregnancy tissue.
Seeking Medical Care
Any vaginal bleeding during pregnancy warrants prompt medical evaluation. Contact a healthcare provider immediately if experiencing moderate to heavy vaginal bleeding, passing tissue, or if bleeding is accompanied by abdominal pain, cramping, fever, or chills. Even light spotting lasting longer than a day should be reported to a healthcare professional within 24 hours.
Self-diagnosis is not appropriate, as only a medical professional can accurately determine the cause of bleeding. A healthcare provider typically performs a pelvic examination, blood tests, and an ultrasound to assess the situation. An ultrasound can differentiate between a subchorionic hematoma, appearing as a crescent-shaped area of blood near the gestational sac, and a miscarriage, which may show an absence of a fetal heartbeat or an empty gestational sac.