Experiencing vaginal bleeding and passing a blood clot during pregnancy is frightening, immediately raising concerns about the health and viability of the pregnancy. This distressing symptom is common in early gestation, affecting up to one in four pregnancies. A clot, which is coagulated blood or tissue, does not automatically mean the loss of the pregnancy. Since bleeding and clotting can signal issues ranging from minor irritations to serious complications, immediate consultation with a medical professional is necessary to determine the underlying cause and assess the status of the fetus.
Understanding Bleeding That Does Not Affect Viability
In many cases, the passage of blood or small clots occurs while the pregnancy remains viable. This bleeding often stems from changes in the uterus and cervix as the pregnancy develops. One common source is cervical irritation, which occurs because the cervix develops an increased supply of blood vessels during pregnancy. This heightened vascularity makes the area sensitive and prone to bleeding, often triggered by sexual intercourse, a physical examination, or a Pap smear.
Another frequent cause of bleeding, which can include the passage of clots, is a subchorionic hematoma (SCH), sometimes called a subchorionic hemorrhage. A SCH represents a collection of blood that accumulates between the outer membrane of the gestational sac, known as the chorion, and the wall of the uterus. When this trapped blood is released, it can exit vaginally as light spotting or heavier bleeding with clots.
The presence of a subchorionic hematoma does not threaten the pregnancy, and most resolve naturally over time. While larger hematomas may be associated with a higher risk of complications, many people with this finding have full-term, healthy deliveries. In the first weeks of pregnancy, some people also experience implantation bleeding. This is typically light spotting, but it may be accompanied by very small clots as the fertilized egg embeds into the uterine lining.
Recognizing Clots and Bleeding Associated With Pregnancy Loss
When bleeding is heavier and accompanied by significant cramping, it is more likely associated with a potential or confirmed pregnancy loss. Medical professionals differentiate between types of miscarriage based on the status of the cervix. A threatened miscarriage is diagnosed when bleeding and cramping are present, but a pelvic examination confirms that the cervical os is still closed.
In this threatened scenario, the fetus may remain viable, and the pregnancy can continue. However, if the bleeding becomes heavier and the pain increases, the situation may progress to an inevitable miscarriage, which is diagnosed when the cervical os is found to be open. An open cervix in the presence of bleeding means the process of pregnancy loss is already underway and cannot be stopped.
The blood passed during a miscarriage is often accompanied by tissue, medically referred to as products of conception (POC). This passed tissue may appear different from a typical blood clot, often looking gray, pink, white, or sometimes resembling a small, fluid-filled sac. Heavy, persistent bleeding paired with severe, often one-sided, abdominal or pelvic pain may signal an ectopic pregnancy. This condition occurs when the fertilized egg implants outside the uterus, usually in a fallopian tube, and requires immediate medical intervention to prevent rupture.
Necessary Actions and Medical Confirmation of Viability
Anyone who experiences bleeding or passes a clot during pregnancy should contact their healthcare provider immediately for guidance. While awaiting medical instruction, it is recommended to rest, avoid using tampons, and refrain from sexual activity. If any tissue or material is passed, it should be collected for examination, as analyzing the contents can help a doctor determine the source of the bleeding.
Confirmation of the pregnancy’s viability requires diagnostic procedures. A pelvic examination allows the provider to inspect the cervix to see if the os is open or closed, determining the type of bleeding event. An ultrasound examination is then performed to visualize the uterus, confirm the location of the pregnancy, and check for a fetal heartbeat.
If the pregnancy is very early and a heartbeat cannot be confirmed, serial blood tests measuring human chorionic gonadotropin (hCG) are necessary. In a viable intrauterine pregnancy, hCG levels are expected to rise by a minimum of 35% to 53% over a 48-hour period, though this rate slows later in gestation. A slower rise, a plateau, or a decrease in hCG levels indicates a nonviable pregnancy or an ectopic pregnancy.