Threatened miscarriage

Pregnancy with bleeding from the uterine cavity through the vagina where the cervix is still closed within the first 20 weeks of pregnancy is a common pregnancy complication, occurring in about 25% of pregnancies. The causes of threatened miscarriage can arise from various factors such as congenital anomalies, chromosomal abnormalities of the fetus, blighted ovum, uterine abnormalities, or hormonal disorders affecting implantation, or some cases with unknown exact causes.

Symptoms of Threatened Miscarriage

Dr. Niwat Aranyakasemsuk, an obstetrician and gynecologist specializing in maternal-fetal medicine at Phyathai 2 Hospital provides information about the dangers related to threatened miscarriage. Symptoms include vaginal bleeding, which can vary in amount, and may or may not be accompanied by lower abdominal pain. In early pregnancy, it may be a normal condition with bleeding from the implantation site of the embryo in the uterine lining, called implantation bleeding or Placental sign or Hartman’s sign, which usually occurs about 17 days after fertilization or 4 and a half weeks from the first day of the last menstrual period. This may be mistaken for symptoms of miscarriage.

Other Conditions with Symptoms Similar to Threatened Miscarriage

Such as molar pregnancy, which may have spotting or heavy bleeding similar to menstruation, sometimes leading to hemorrhage. Ectopic pregnancy often presents with lower abdominal pain and vaginal bleeding if the gestational sac ruptures, causing internal bleeding in the abdomen. Patients may experience pallor, low blood pressure, and shock, which can be life-threatening if not promptly diagnosed and treated. Therefore, pregnant women with vaginal bleeding or lower abdominal pain should see a doctor immediately.

Diagnosis of Threatened Miscarriage

High-frequency ultrasound or sonography is a highly accurate diagnostic tool that can differentiate ectopic pregnancy and molar pregnancy from normal pregnancy. It can check whether the embryo is still alive by observing the heartbeat, fetal movements, and the condition of the gestational sac in the uterus, including the yolk sac and the number of embryos.

In cases where a small gestational sac is detected but the yolk sac or embryo is not yet visible, follow-up examinations may be necessary because the pregnancy is very early and the embryo is not yet visible. Transvaginal ultrasound can detect the embryo about 1-2 weeks earlier than abdominal ultrasound.

Additionally, blood hormone level tests such as hCG can indicate whether the embryo is alive and growing. If the embryo has died, hormone levels will decrease. These tests can also help differentiate ectopic pregnancy from normal pregnancy by monitoring hCG level changes.

Diagnostic Results

• Normal viable pregnancy: 39.7%
• Abnormal pregnancy: 60.3%
• Embryo or fetus that has died: 13.8%
• Missed abortion: 23.2%
• Complete miscarriage: 12.5%
• Incomplete miscarriage: 5.8%
• Molar pregnancy: 1.8%
• Ectopic pregnancy: 3.1% 

About 50% will end in miscarriage regardless of treatment method. Among these patients, about 50% are cases of missed abortion or where the embryo has already died. The remaining 50%, if the embryo is still alive and well cared for, vaginal bleeding will decrease and there is a chance to continue the pregnancy.

Statistics show that if the pregnancy is over 8 weeks and fetal heartbeat is detected by ultrasound, there is a 95% chance of continuing the pregnancy.

Treatment of Threatened Miscarriage

In cases of viable pregnancy, ultrasound will show a gestational sac containing the yolk sac, embryo, and fetal vital signs such as heartbeat (Doppler Ultrasound) or blood flow in the fetus (Color Doppler Ultrasound). If the embryo is alive, the doctor will closely monitor the pregnancy and advise the pregnant woman as follows:

• Rest as much as possible and avoid excessive walking
• Avoid risk factors affecting fetal implantation such as abstaining from sexual intercourse, heavy lifting, or any activities that strain the abdomen or increase intra-abdominal pressure
• Follow up closely with treatment, maintain a relaxed mind, eat nutritious food, and take folic acid

Treatment with oral or injectable hormones, commonly called miscarriage prevention drugs, involves progesterone hormones that help the embryo implant in the uterine wall. This is beneficial in cases where bleeding is due to hormone deficiency. However, hormone level testing by blood sampling may take time, so treatment is usually given to suspected hormone-deficient cases but only when normal pregnancy signs are confirmed in the uterine cavity and fetal heartbeat is detected. Otherwise, it may support an abnormal pregnancy, leading to prolonged miscarriage, prolonged bleeding, and possible infection complications.

In cases of non-viable pregnancy, the pregnancy usually ends naturally with uterine contractions expelling the gestational sac and placenta. If completely expelled (complete abortion), abdominal pain gradually subsides, and bleeding decreases until it stops. If incomplete abortion occurs, abdominal pain worsens, bleeding increases, and some cases may experience hemorrhage. In such cases, prompt medical attention for uterine curettage is necessary.

In cases where diagnosis is inconclusive, supportive treatment may be considered initially with follow-up ultrasound in 4-7 days, especially in very early pregnancies where the yolk sac or embryo is not yet visible. This helps differentiate from molar pregnancy and prevents mistakenly performing uterine curettage on a very early normal pregnancy.