A threatened miscarriage is a medical diagnosis given when vaginal bleeding occurs during the first 20 weeks of pregnancy, but the pregnancy is still considered viable. This means the cervix remains closed, and the fetus still shows signs of life, typically confirmed by a detectable heartbeat on an ultrasound. This experience is relatively common, occurring in about 15% to 20% of pregnancies before the 20-week mark, with many continuing successfully to term. The diagnosis indicates a potential risk, prompting close medical monitoring.
Physical Manifestations of a Threatened Miscarriage
The most noticeable indicator of a threatened miscarriage is the presence of vaginal bleeding, which can vary significantly in appearance and volume. This bleeding may present as light spotting, a slight pink or brownish discharge, or it can be a heavier, bright red flow similar to a light menstrual period. The color of the blood is not a definitive predictor, ranging from bright red to darker brown. Darker brown blood often indicates older, less active bleeding.
The volume of blood loss is generally mild, though it can include the passing of small clots or tissue. Bleeding can last for several days or weeks, fluctuating in intensity. Patients must monitor the flow, noting if it is heavy enough to soak through a sanitary pad in an hour for two or more consecutive hours.
Accompanying the bleeding, a person may experience abdominal cramps or pain, typically described as a dull, period-like ache. This discomfort is usually mild, located in the lower abdomen, and may sometimes be felt in the lower back. A key feature of a threatened miscarriage is that the cramping remains manageable and is not intensely sharp.
Distinguishing Threatened Miscarriage from Other Bleeding
Not all bleeding experienced in early pregnancy indicates a threatened miscarriage; other common causes exist. One cause is implantation bleeding, which happens very early, around the time a period would be expected, and is characterized by light pink or brown spotting. It typically lasts only a day or two and is not usually accompanied by significant cramping or heavy flow.
Another source of light bleeding is cervical irritation, common because the cervix becomes highly vascularized during pregnancy. This type of bleeding is often seen following sexual intercourse or a pelvic examination and is usually brief and light. Unlike a threatened miscarriage, this bleeding is not usually associated with persistent abdominal pain or cramping.
A threatened miscarriage differs from other forms of miscarriage in the physical presentation of the cervix. In cases like inevitable miscarriage, the cervix has begun to open or dilate, and the bleeding is often heavier with significant pain. The definitive feature of a threatened miscarriage is the closed cervical opening, which a healthcare provider confirms during a physical examination.
Medical Confirmation and Evaluation
When a person presents with vaginal bleeding, a healthcare provider initiates an evaluation to confirm a diagnosis of threatened miscarriage and assess viability. A pelvic examination checks the state of the cervix, as a closed cervical opening is a prerequisite for this diagnosis. This exam also helps rule out other non-pregnancy related causes of bleeding, such as infection or cervical polyps.
A transvaginal or abdominal ultrasound establishes the location of the pregnancy and determines its viability. The presence of a fetal heartbeat is the most critical indicator of viability, suggesting a better prognosis. The ultrasound also assesses for potential causes of bleeding, such as a subchorionic hematoma (a collection of blood between the uterine wall and the gestational sac).
Blood tests monitor the levels of human chorionic gonadotropin (hCG) and progesterone. Serial hCG measurements, taken 48 hours apart, ensure the hormone is increasing at an appropriate rate, indicating a developing pregnancy. Low or declining hCG levels, or low progesterone levels, can suggest a higher risk of progression to a completed miscarriage.
Immediate Next Steps and Prognosis
Management for a threatened miscarriage is typically supportive, focusing on close monitoring and expectant management. Current medical consensus suggests rest and avoidance of strenuous activity, moving away from strict bed rest. Progesterone supplementation may be offered when low levels of the hormone are detected, though studies show mixed results regarding its effectiveness.
The most reassuring factor for the prognosis is the confirmation of a fetal heartbeat on ultrasound. Once a heartbeat is detected, the likelihood of the pregnancy continuing successfully is high, with the rate of subsequent miscarriage dropping significantly. Factors that may worsen the prognosis include heavy, persistent bleeding, a large subchorionic hematoma, or an abnormal fetal heart rate, such as bradycardia.
Patients are advised to monitor symptoms closely and seek immediate medical attention if the condition worsens. Urgent care is necessary if the bleeding becomes heavy, defined as soaking more than one sanitary pad per hour for two or more hours. Severe, constant abdominal pain, fever, or passing large amounts of tissue should prompt an immediate trip to the emergency department, as these may indicate an inevitable or incomplete miscarriage.