Molar Pregnancy

What is molar pregnancy?

A molar pregnancy is an uncommon complication of pregnancy in which the tissue that would normally develop into the placenta grows abnormally. The placenta is the organ that connects a developing baby to the wall of the womb (uterus) and supplies it with oxygen and nutrients. In a molar pregnancy, this tissue forms a mass of fluid-filled sacs, sometimes described as looking like a cluster of grapes, instead of a healthy placenta. Doctors also call this condition a hydatidiform mole, and it belongs to a group of conditions known as gestational trophoblastic disease (GTD), which means abnormal growth of the cells that form the placenta.

There are two main types. In a complete molar pregnancy, there is no embryo at all; only abnormal placental tissue develops. In a partial molar pregnancy, some placental tissue is abnormal and there may be an embryo, but it cannot survive because of serious genetic problems. In both cases, the pregnancy cannot continue, and treatment is needed to remove the abnormal tissue and to check that it does not return.

A molar pregnancy can happen to anyone who can become pregnant. It is not caused by anything a person did or did not do. Most molar pregnancies are benign, meaning they are not cancer, but in a minority of cases the abnormal cells can persist and behave more like a cancer, which is why careful follow-up after treatment is so important.

Molar pregnancy symptoms

In the early weeks, a molar pregnancy often feels like a normal pregnancy. A home pregnancy test is usually positive, and there may be typical early signs such as breast tenderness or nausea. Symptoms that raise concern tend to appear during the first trimester or early second trimester. Common molar pregnancy symptoms include:

• Vaginal bleeding, which may be dark brown or bright red, and may come and go
• Severe nausea and vomiting, often worse than expected in pregnancy
• Passing small grape-like cysts from the vagina
• Pelvic pressure or pain
• A uterus that feels larger than expected for the stage of pregnancy
• Signs of high blood pressure appearing unusually early in pregnancy
• Symptoms of an overactive thyroid, such as a fast heartbeat, feeling shaky, or heat intolerance
• Symptoms of anemia (low red blood cells), such as tiredness or breathlessness, if bleeding has been heavy

Symptoms can differ by type. A complete molar pregnancy is more likely to cause heavy bleeding, marked nausea, a rapidly enlarging uterus, and very high levels of the pregnancy hormone human chorionic gonadotropin (hCG). A partial molar pregnancy often produces milder or fewer symptoms and is sometimes only recognized when tissue is examined after what appeared to be a miscarriage.

Because many pregnancies are now checked with an early ultrasound, a molar pregnancy is increasingly found before dramatic symptoms develop. Any bleeding in pregnancy deserves medical assessment, but bleeding alone does not mean a molar pregnancy is present; many other causes are far more common.

Causes and risk factors

Molar pregnancy causes lie in a genetic error at the moment of fertilization, when a sperm joins an egg. In a healthy pregnancy, the embryo receives one set of chromosomes (the structures that carry genetic information) from the egg and one set from the sperm. In a molar pregnancy, this balance is disturbed.

• Complete molar pregnancy: in most cases an egg that carries no usable genetic material is fertilized by one sperm, whose chromosomes then duplicate, or by two sperm. All of the genetic material comes from the father, and no embryo forms.
• Partial molar pregnancy: a normal egg is fertilized by two sperm, or by one sperm that duplicates its chromosomes. The resulting cells carry three sets of chromosomes instead of two. An embryo may start to develop but cannot survive.

These errors happen by chance. They are not linked to lifestyle choices, stress, or anything a person did during early pregnancy, and they cannot be caused by a partner. Nevertheless, doctors recognize several factors that appear to make a molar pregnancy somewhat more likely:

• Age: molar pregnancy is more common in people who become pregnant in their late thirties and beyond, and slightly more common in those in their early teens.
• Previous molar pregnancy: having had one molar pregnancy modestly increases the chance of another, although most later pregnancies are healthy.
• History of miscarriage: some studies suggest a link with repeated pregnancy loss.
• Dietary factors: a diet low in certain nutrients, such as carotene (a form of vitamin A) or animal fat, has been associated with a higher risk in some research, although this link is not fully understood.
• Geographic and ethnic differences: rates vary between regions of the world, for reasons that are not entirely clear.

It is worth stressing that most people with these risk factors never have a molar pregnancy, and many people who do have one had no known risk factors at all.

Diagnosis

Molar pregnancy diagnosis usually begins because of symptoms such as bleeding, or because a routine early ultrasound looks unusual. Doctors confirm the diagnosis using a combination of imaging, blood tests, and laboratory examination of tissue.

• Pelvic ultrasound: this is the main imaging test. Sound waves create a picture of the uterus. In a complete molar pregnancy, the ultrasound may show a mass of tissue with many small cysts and no embryo, sometimes described as a snowstorm or honeycomb appearance. In a partial molar pregnancy, the picture is less typical: there may be an abnormally thick placenta and an embryo or fetus that is not developing normally. A transvaginal ultrasound, in which a slim probe is placed in the vagina, gives a clearer view early in pregnancy.
• Blood hCG test: hCG is the hormone that pregnancy tests detect. In a molar pregnancy, particularly a complete mole, hCG levels are often much higher than expected for the stage of pregnancy. A very high or unusually rising level supports the diagnosis and provides a baseline for later monitoring.
• Other blood tests: your doctor may check blood count, thyroid function, kidney and liver function, and blood type, because a molar pregnancy can affect the thyroid and cause anemia, and because treatment may require preparation for possible bleeding.
• Tissue examination (histopathology): the definitive diagnosis is made when tissue removed from the uterus is examined under a microscope by a pathologist, a doctor who specializes in diagnosing disease from tissue samples. This confirms whether the pregnancy was a complete or partial mole. Special genetic tests on the tissue are sometimes used when the picture is unclear.
• Chest X-ray or further imaging: if there is concern that abnormal cells have spread beyond the uterus, imaging of the chest, and occasionally other areas, may be arranged.

Sometimes a molar pregnancy is only diagnosed after a miscarriage or pregnancy termination, when tissue is routinely sent for examination. This is one reason why doctors often recommend laboratory examination of tissue after any early pregnancy loss.

Molar pregnancy treatment options

A molar pregnancy cannot develop into a healthy baby, so molar pregnancy treatment focuses on removing the abnormal tissue safely, protecting the person’s health, and monitoring closely to make sure no abnormal cells remain. Care is typically led by a gynecologist, a doctor who specializes in the female reproductive system, working with other specialists as needed. Within Acibadem, this care is managed through the Gynecology & Obstetrics department.

Suction evacuation (dilation and curettage). The standard treatment is a minor operation in which the cervix, the opening of the uterus, is gently widened and the abnormal tissue is removed with gentle suction. Doctors often call this a D&C or suction curettage. It is usually done under general anesthesia or sedation and often takes less than an hour. Ultrasound may be used during the procedure to help ensure the uterus is emptied. Because the tissue is rich in blood vessels, there is a risk of heavier-than-usual bleeding, so the procedure is done in a hospital where this can be managed. Removed tissue is sent for microscopic examination.

Medication during the procedure. Drugs that make the uterus contract may be given to reduce bleeding once the tissue has been removed. Medication-only treatment to expel the tissue is generally not preferred for molar pregnancy because it may be less complete and may carry a higher chance of needing further treatment, although your doctor will explain what is suitable in your situation.

Hysterectomy. In some cases, particularly for people who do not wish to have more children, or when bleeding is severe, removal of the uterus (hysterectomy) may be offered. This removes the tissue completely but does not entirely remove the need for follow-up hCG testing, because abnormal cells can occasionally persist elsewhere.

Follow-up hCG monitoring. After the tissue is removed, blood hCG levels are measured at regular intervals until they return to normal and stay there. This is a central part of treatment, not an optional extra. Falling hCG levels show that the abnormal cells are gone; levels that plateau or rise suggest that some abnormal tissue remains. The length of follow-up varies with the type of mole and how quickly hCG falls; it may last several weeks to many months. Some health systems run dedicated registration and follow-up programs for this purpose.

Contraception during follow-up. Doctors usually advise avoiding a new pregnancy until follow-up is complete, because a new pregnancy also raises hCG and would make it impossible to tell whether abnormal cells had returned. Reliable contraception is recommended during this period; your doctor may discuss which methods are appropriate.

Treatment of persistent disease. In a minority of cases, abnormal trophoblastic cells continue to grow after evacuation. This is called persistent gestational trophoblastic disease or gestational trophoblastic neoplasia. It is usually detected through hCG monitoring before it causes symptoms. Treatment is typically chemotherapy, medication that destroys rapidly dividing cells. Many people need only a single drug, such as methotrexate, while more advanced disease may need a combination of drugs. This form of disease is considered highly responsive to chemotherapy, and fertility is often preserved after treatment. Care at this stage generally involves a specialist team with experience in gestational trophoblastic disease.

Rh immunoglobulin. If your blood type is Rh negative, you may be offered an injection to prevent your body from forming antibodies that could affect a future pregnancy, as after any pregnancy loss.

Living with molar pregnancy and outlook

For most people, the outlook after a molar pregnancy is good. Once the tissue is removed and hCG levels return to normal, the condition is considered resolved, and the large majority of people go on to have healthy pregnancies in the future if they wish. Even when persistent disease develops and chemotherapy is needed, the condition is generally very treatable, although no outcome can be guaranteed and each situation differs.

Physically, recovery from suction evacuation is usually fairly quick. Light bleeding or spotting for a week or two is common. Your doctor may advise avoiding tampons, sexual intercourse, and swimming for a short time to reduce the risk of infection. Periods typically return within a few weeks, although timing varies.

Emotionally, a molar pregnancy can be difficult. It involves the loss of a pregnancy, often a wanted one, combined with worry about health and a lengthy period of blood tests. Feelings of grief, anxiety, guilt, or anger are common and understandable. It may help to know that nothing you did caused the molar pregnancy. Support from a partner, family, friends, counselors, or support groups for pregnancy loss can be valuable, and your care team can point you toward appropriate resources.

When planning a future pregnancy, doctors generally suggest waiting until follow-up is complete. Because the chance of another molar pregnancy is slightly higher than average, an early ultrasound is often recommended in the next pregnancy, and some doctors also check hCG levels a few weeks after any future birth or pregnancy loss.

Frequently asked questions

What are the first molar pregnancy symptoms?

Early on, a molar pregnancy often feels like any other pregnancy. The first noticeable sign is commonly vaginal bleeding, which may be brown or red, sometimes with unusually severe nausea and vomiting. Some people notice pelvic pressure or that their abdomen seems to be growing faster than expected. Because these signs overlap with other pregnancy problems, only an ultrasound and blood tests can tell the difference.

What causes a molar pregnancy?

Molar pregnancy causes come down to a random error in the genetic material at fertilization, usually involving an egg with no usable chromosomes or an egg fertilized by two sperm. The result is tissue that grows abnormally instead of forming a healthy placenta and embryo. It is not caused by anything a person or partner did, and it is not an infection or an inherited condition in the usual sense.

How is molar pregnancy diagnosis confirmed?

Doctors usually suspect a molar pregnancy from a pelvic ultrasound that shows characteristic cystic tissue, together with a blood hCG level that is higher than expected. The diagnosis is confirmed when tissue removed from the uterus is examined under a microscope by a pathologist. Additional blood tests and sometimes imaging are used to check overall health and to rule out spread.

What is the standard molar pregnancy treatment?

The usual molar pregnancy treatment is suction evacuation of the uterus, a short procedure performed under anesthesia in a hospital. This is followed by regular blood tests to track hCG until it returns to normal. Hysterectomy is an option for some people who do not want future pregnancies. If abnormal cells persist, chemotherapy is typically very effective.

Can a molar pregnancy turn into cancer?

Most molar pregnancies are benign and resolve completely after treatment. In a minority of cases, the abnormal cells keep growing, a condition called gestational trophoblastic neoplasia, which can behave like a cancer and occasionally spread. This is why hCG follow-up is essential: it detects persistent disease early, when it is generally highly curable with chemotherapy.

How long do I have to wait before trying to get pregnant again?

Doctors generally advise waiting until hCG monitoring is complete and your care team confirms it is safe. The length of this period depends on the type of mole and how quickly hCG normalizes; it may range from a few months to around a year, and longer if chemotherapy was needed. Reliable contraception is recommended in the meantime.

Will I be able to have a healthy pregnancy after a molar pregnancy?

In many cases, yes. Most people who have had a molar pregnancy and completed follow-up go on to conceive and carry healthy pregnancies. The chance of another molar pregnancy is slightly higher than average, so an early ultrasound is usually offered in the next pregnancy, but a repeat is still uncommon.

When to see a doctor

Any bleeding or unusual symptoms during pregnancy should be assessed by a doctor or midwife, even though most causes are not serious. If you have been treated for a molar pregnancy, keep all scheduled hCG blood tests and follow-up appointments, and let your care team know if you think you may be pregnant during the monitoring period.

Seek urgent medical care if you experience any of the following:

• Heavy vaginal bleeding, such as soaking through a pad every hour or passing large clots
• Severe or worsening abdominal or pelvic pain
• Fainting, dizziness, or a racing heartbeat
• Fever or foul-smelling vaginal discharge after treatment
• Vomiting so severe that you cannot keep fluids down
• Sudden severe headache, vision changes, or swelling with high blood pressure
• Shortness of breath, chest pain, or coughing up blood, which can rarely signal spread of abnormal cells to the lungs
• Persistent or returning bleeding after your hCG level had returned to normal

These warning signs do not necessarily mean something serious is happening, but they need prompt evaluation so that bleeding, infection, or persistent disease can be treated early.