What is Threatened Miscarriage?
A miscarriage is often described as the failure of a pregnancy before reaching 20 weeks. A “threatened miscarriage” involves experiencing symptoms like vaginal bleeding and uterus cramping during what would otherwise be a healthy pregnancy before hitting the 20-week mark. Most often, this happens during the first three months of pregnancy. In other words, a healthy, or “viable,” pregnancy is one that’s likely to result in a baby being born. First trimester vaginal bleeding and cramps are common clues of early miscarriage and incomplete miscarriage, but the specific signs of a threatened miscarriage include a closed cervix, no passing of pregnancy tissue, and no visible signs of a fetus or embryo failing on a pelvic ultrasound scan.
Around 25% of pregnancies involve some degree of vaginal bleeding in the first trimester, and about half of these could result in an early pregnancy loss. The bleeding experienced during a threatened miscarriage is usually light to moderate; heavy bleeding exceeding the typical menstrual flow could signal a higher risk of losing the pregnancy. Other common symptoms include occasional cramping, upper pubic area pain, pressure in the pelvic area, or lower back pain.
Medical professionals assess a threatened miscarriage based on the point of pregnancy or gestational age. Initially, the focus is on confirming the pregnancy’s location to rule out an ectopic pregnancy, which can also cause vaginal bleeding and lower abdominal pain. After confirming a pregnancy within the uterus, doctors will then look to determine the viability or health of the pregnancy through a pelvic exam and an ultrasound. If the ultrasound doesn’t detect a heartbeat, the doctor may schedule a series of follow-up ultrasounds to distinguish between early viable pregnancy and pregnancy loss.
The term “abortion”, in the past, has applied to any pregnancy loss before 20 weeks. However, many top professional bodies now suggest using different forms of the terms “miscarriage” or “pregnancy loss”, like “threatened miscarriage” or “threatened pregnancy loss,” as these terms are more preferred by patients.
What Causes Threatened Miscarriage?
The exact cause of a threatened miscarriage (a situation where there are signs that a miscarriage might happen) is sometimes hard to pinpoint. However, possible causes could include subchorionic hemorrhage or hematoma, upcoming spontaneous miscarriage, or bleeding unrelated to pregnancy.
To clarify, a subchorionic hemorrhage or hematoma is bleeding that occurs between the baby’s protective membranes and the mother’s womb lining. This bleeding happens in about 18% to 22% of pregnancies. If the bleeding is small, it’s not typically associated with a higher risk of miscarriage. However, if the bleeding area is larger than two-thirds of the baby’s sac, the risk of losing the pregnancy increases.
In cases where the bleeding signals an upcoming early miscarriage, chromosomal abnormalities in the fetus are usually the root cause. These abnormalities are found in at least half of the pregnancies affected.
Bleeding during a seemingly healthy pregnancy could also be unrelated to pregnancy. It could be due to vaginitis (an inflammation of the vagina), cervicitis (an inflammation of the cervix), or cervical polyps (small, benign growths on the cervix).
Risk Factors and Frequency for Threatened Miscarriage
Threatened miscarriage can happen in any pregnancy, no matter the mother’s age, race, other health conditions, lifestyle, or income level. Around 25% of pregnant individuals might experience some degree of bleeding or spotting during the first three months of pregnancy. However, if a fetal heartbeat can be detected, there is an 11% chance of miscarriage.
Signs and Symptoms of Threatened Miscarriage
Threatened miscarriage is a condition where women may experience bleeding and abdominal cramps in the first three months of pregnancy. Sometimes, women may not know they are pregnant and may think they are just having irregular periods. It’s important to carry out a detailed evaluation, because these symptoms can also happen in other types of pregnancy complications.
The likely due date can be calculated using the first day of the woman’s last menstrual cycle. However, the most accurate method is a first-trimester ultrasound if available. This scan can also confirm that the pregnancy is located inside the uterus. The amount of bleeding can vary from light spotting to heavy bleeding. When the bleeding is heavier, there is a higher risk of miscarriage.
In threatened miscarriages, the patient is typically still in good general condition. Even when the pregnancy leads to a miscarriage, only 1% of women need a blood transfusion. To understand the level of bleeding, the doctor will usually ask about how often menstrual products need to be changed, whether any clots or tissue have been passed, and if there are any related symptoms like feeling dizzy or faint.
Bleeding after activities like having sex or having a pelvic exam may suggest a condition affecting the cervix or the vagina, rather than the uterus. Doctors will also ask about any cramping or pain. These symptoms can range from zero pain to severe discomfort similar to menstrual cramps. If the pain is severe, it may indicate a higher risk of miscarriage.
A detailed physical examination is also necessary, checking vital signs, and focusing on the abdomen and pelvis. Patients only experiencing a threatened miscarriage will be stable and have normal cardiovascular and respiratory findings. For example, the belly will typically not be tense, full, or painful to the touch, although there might be some discomfort over the uterus area. Highly significant pain in the belly or rigidness of the belly may require an urgent consultation with a specialist.
A vaginal examination helps to assess the amount and source of bleeding, and to see whether there are any nonpregnancy causes for the bleeding, or whether tissue from the foetus can be seen in the cervix or vagina. During the exam, any blood in the vagina or cervix may need to be removed to allow for better visualization. It’s usually conducted using suction, cotton swabs, or small forceps.
The findings during vaginal examination in cases of threatened miscarriage often include a closed cervical opening (no fetal or embryonic tissue in the vagina), though blood may be present. There is usually no excessive pain when the cervix is moved, but depending on how severe the cramps are, women may feel some discomfort in the uterus or in the adnexal (related to the fallopian tubes and ovaries) regions. Substantial pain of the pelvic organs, especially when a bad-smelling vaginal discharge is present, could suggest an infection.
The vaginal examination also helps rule out other possible causes of vaginal bleeding in pregnancy. These can include injuries to the vulva, vagina, and cervix, conditions which can lead to abnormal cell boost or new cell growth, polyps, fibroids, or a cervical condition that makes it bleed easily due to infection (like vaginal candidiasis, chlamydia, genital warts). Furthermore, a lump or swelling in the adnexal region could indicate an ectopic pregnancy or other problems related to female reproductive system, such as a cyst or twisted ovary.
Testing for Threatened Miscarriage
If you’re experiencing symptoms of a threatened miscarriage, your healthcare provider will conduct several tests. Let’s break down what that entails.
A pelvic ultrasound, which uses sound waves to create an image of your internal organs, will allow doctors to look inside your uterus. This will help them determine the location and viability of your pregnancy, as well as identify any potential complications.
To let doctors understand the status of your pregnancy by the amount of pregnancy hormone (β-hCG) in your blood, a serum quantitative beta-human chorionic gonadotropin test will be performed. A blood test will also be done to determine your blood type and Rh status, which can be important in case a blood transfusion is needed. Notably, the Rh factor could have implications if the mother is Rh-negative and the baby is Rh-positive.
Your doctor might also want to look at your hemoglobin and hematocrit levels. These tests measure the amount of red blood cells in your blood and can help assess your overall health and level of blood loss. Additional tests may be performed if there are concerns about infection. These may include cultures of your cervical secretions, blood, or urine, a complete blood count, and a comprehensive metabolic panel.
When analyzing the ultrasound, doctors look for evidence of pregnancy inside the uterus, ruling out an ectopic pregnancy (a pregnancy outside of the uterus). They’re also checking to ensure the baby’s heart is beating. If signs of potential miscarriage are detected, such as no fetal cardiac activity when the baby’s size suggests there should be, further steps will be taken.
In some cases, β-hCG levels are watched over time to verify a pregnancy’s progression. This helps in determining if a pregnancy is failing or potentially located outside the uterus, which can be harmful. An ultrasound should primarily be used for diagnosis once a heartbeat is detected.
Finally, to prevent a condition known as Rh alloimmunization, where an Rh-negative mother develops antibodies against Rh-positive baby blood, Rh-negative mothers experiencing vaginal bleeding may be given Rh(D)-immune globulin. This prevents the development of these antibodies that could lead to hemolytic disease of the newborn in future pregnancies.
In many cases, additional tests like urine analysis might be done, especially if similar symptoms could potentially indicate a urinary tract infection. If a pelvic infection is suspected, further testing is conducted.
In summary, these procedures aim to locate and assess the pregnancy’s viability, consider any potential complications, and address any concerns that the doctor may have.
Treatment Options for Threatened Miscarriage
If a patient has a viable pregnancy but is diagnosed with a condition called “threatened miscarriage,” the general approach is to wait and see what happens – this is known as “expectant management.” This would follow after ruling out any other possible causes of the symptoms. If the patient experiences further bleeding, it is recommended to repeat the test called a pelvic ultrasound. If there’s uncertainty about the location or viability of the pregnancy, more ultrasounds and hormone level checks, specifically β-hCG levels, will be performed.
Progesterone supplementation is one treatment that has been evaluated for reducing the risk of pregnancy loss in certain high-risk situations, like a threatened miscarriage or a shortened cervix. However, this treatment doesn’t seem to help much for people without a history of miscarriage—it’s usually only advised if specific measurements of the cervix are below certain levels. That said, this hormone therapy seems to be beneficial for people with a history of early pregnancy loss. In these cases, symptoms of vaginal bleeding might prompt the recommendation to start progesterone, which would be taken until around the 4th month of pregnancy.
One concern during threatened miscarriage is something called alloimmunization, which occurs when the immune system creates antibodies against foreign proteins, such as the Rh(D) antigen found on fetal blood cells. Though the exact risk factors are not completely clear, doctors do know that heavier bleeding, later stage of pregnancy, and certain surgical procedures can increase the risk. Medical organizations have different recommendations on if and when to use a treatment called Rh(D)-immune globulin to prevent alloimmunization. Therefore, your doctor will assess which course of action to take, depending on your specific situation.
Patients should be reminded how vital it is to attend all follow-up appointments. They should also know to seek medical attention sooner if they experience any concerning symptoms, like very heavy bleeding, severe abdominal pain, or fever. And patients should be reassured that they are not responsible for causing these symptoms.
Contrary to some beliefs, bed rest, or decreased activity, is not proven to prevent early pregnancy loss. Whilst some doctors might advise patients to avoid strenuous activities and vaginal intercourse until the bleeding stops, this advice is not backed by scientific evidence. Patients are generally encouraged to take prenatal vitamins with folic acid supplements as a part of their routine care.
What else can Threatened Miscarriage be?
If a pregnant person arrives at a hospital with vaginal bleeding and pelvic pain, it can mean a variety of things. It might not always be the threat of a miscarriage. There are other conditions that doctors have to rule out before they can determine the cause. Some of these include:
- Pregnancy-related issues like ectopic pregnancy, early pregnancy loss such as inevitable, incomplete, complete, or septic miscarriage, gestational trophoblastic disease or cervical incompetence (common in the second trimester)
- Conditions relating to the vulva, vagina, and cervix like trauma, yeast infections, bacterial infection, chlamydia infection, genital warts, cervical polyps, or cervical cancer
- Issues with the adnexa (structures near the uterus) like a ruptured corpus luteum cyst, or adnexal torsion (twisting of the ovaries or fallopian tubes)
- Other conditions like appendicitis, urinary tract infection, or inflammatory bowel disease
Ultrasound and β-hCG assessments can help doctors exclude ectopic pregnancy and early pregnancy loss. A crucial part of distinguishing a threatened miscarriage from other types of early pregnancy loss is using pelvic ultrasound and examining the patient physically.
In the case of a threatened miscarriage, the cervical opening (os) is closed, and the ultrasound shows signs of a potentially successful pregnancy. This helps doctors tell a threatened miscarriage apart from other types of miscarriage. In a miscarriage that cannot be prevented (inevitable), the cervical os is open, and no pregnancy tissue (POC) is visible in the vaginal vault. In the case of an incomplete miscarriage, the cervix is open with partial passage of POC. A nonviable pregnancy, where the baby can’t survive, immediately rules out the possibility of a threatened miscarriage.
By using ultrasounds and understanding the patient’s medical history, doctors can also discount other causes related to the adnexa and causes unrelated to pregnancy like appendicitis. Physical exams and other appropriate tests can typically help exclude causes related to the vulva, vagina, and cervix.
What to expect with Threatened Miscarriage
Bleeding and stomach cramps in the early stages of pregnancy are very common. Research shows that about one in four pregnant people experience vaginal bleeding before they reach 20 weeks of pregnancy, and between 12% to 57% of these will sadly experience a miscarriage in the early stages of pregnancy. The chance of a miscarriage is higher if the bleeding is heavy and is accompanied by pain or cramps as opposed to light bleeding or spotting.
Pregnancies where there is a risk of miscarriage also have a higher chance of complications occurring later in the pregnancy. These complications can include the pregnancy ending prematurely, the water breaking early before the birth (preterm premature rupture of membranes), slow growth of the baby whilst inside the womb (intrauterine fetal growth restriction), and detachment of the placenta from the womb (placental abruption).
In addition to the physical complications, people who experience a miscarriage in the early stages of pregnancy also face a higher risk of emotional struggles including depression, trouble sleeping, anger, and relationship difficulties.
Possible Complications When Diagnosed with Threatened Miscarriage
Complications that can occur due to a threatened miscarriage include:
- Early pregnancy loss
- Anemia, which is a condition where you lack enough healthy red blood cells to carry adequate oxygen to your body’s tissues
- Mental health issues such as depression and anxiety
- Negative effects on pregnancy later on, like early labor or placental abruption, which is when the placenta separates from the inner wall of the uterus before birth
Preventing Threatened Miscarriage
Patients should be given information both in conversation and in writing. It’s important for the patient to know if her pregnancy can continue, and that many pregnancies do continue, particularly if the bleeding is light and there’s no accompanying discomfort. She should also be made aware of the possibility of a miscarriage and understand that in many cases, there’s unfortunately no guaranteed way to prevent this from happening. A threatened miscarriage can cause the patient to feel a lot of guilt or anxiety. It’s essential to assure the patient that a miscarriage, if it occurs, is not her fault.
Doctors should clearly explain what to expect if the patient’s medical care involves waiting and monitoring her condition, which can include normal symptoms such as mild to moderate bleeding and cramping. If the patient experiences uncontrolled pain, fever, or heavy bleeding that soaks 1 to 2 pads every hour for two or more hours, she should seek help quickly from her pregnancy care provider or go to an emergency department.
If the patient needs pain relief, she can take acetaminophen or paracetamol but should generally avoid drugs known as NSAIDs while her pregnancy is still possible. Unlike the old days, bed rest and limiting activities are no longer recommended. Also, even though many doctors suggest resting the pelvic area until the symptoms go away, there isn’t solid evidence that supports this advice.
