Hydatidiform mole

Other Names: HYDM; Hydatid mole; Molar pregnancy

Hydatiform mole (also known as molar pregnancy) is a subcategory of diseases under gestational trophoblastic disease (GTD), which originates from the placenta and can metastasize.It is unique because the tumor originates from gestational tissue rather than from maternal tissue. Other forms of gestational trophoblastic disease include gestational choriocarcinoma (which can be extremely malignant and invasive) and placental site trophoblastic tumors.

Transvaginal ultrasonography showing a molar pregnancy.

Molar pregnancy in ultrasound

Epidemiology

There is a very low frequency of hydatiform moles. In North America and Europe, the frequency has been described as 60 to 120/100,000 pregnancies for hydatiform moles. The frequency has been shown to be higher in other countries of the world. Certain risk factors increase the prevalence of molar pregnancies:

Extremes of maternal age:

• Greater than 35 years old carries a five to ten-fold increased risk risk
• Early teenage years, usually less than 20 years old
• Previous molar pregnancy increases the risk 1% to 2% for future pregnancies
• Women with previous spontaneous abortions or infertilities
• Dietary factors including patients that have diets deficient in carotene (vitamin A precursor) and animal fats
• Smoking

Cause

HM, or molar pregnancy, results from abnormal fertilization of the oocyte (egg). It results in an abnormal fetus. The placenta grows normally with little or no growth of the fetal tissue. The placental tissue forms a mass in the uterus. On ultrasound, this mass often has a grape-like appearance, as it contains many small cysts.

Chance of mole formation is higher in older women. A history of mole in earlier years is also a risk factor.

Molar pregnancy can be of two types: Partial molar pregnancy: There is an abnormal placenta and some fetal development. Complete molar pregnancy: There is an abnormal placenta and no fetus. There is no way to prevent formation of these masses.

Signs and symptoms

The symptoms of molar pregnancy, which may include vaginal bleeding, severe morning sickness, stomach cramps, and high blood pressure, typically begin around the 10th week of pregnancy. Because the embryo does not form or is malformed in molar pregnancies, and because there is a small risk of developing a cancer called choriocarcinoma, a D&C is usually performed.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Anemia(Low number of red blood cells or hemoglobin)
• Enlarged uterus
• Menometrorrhagia
• Nausea and vomiting
• Preeclampsia
• Spontaneous abortion

5%-29% of people have these symptoms

• Hyperthyroidism(Overactive thyroid)

Diagnosis

Your health care provider will perform a pelvic exam, which may show signs similar to a normal pregnancy. However, the size of the womb may be abnormal and there may be no heart sounds from the baby. Also, there may be some vaginal bleeding. A pregnancy ultrasound will show a snowstorm appearance with an abnormal placenta, with or without some development of a baby.

Tests done may include:

• hCG (quantitative levels) blood test
• Abdominal or vaginal ultrasound of the pelvis
• Chest x-ray
• CT or MRI of the abdomen (imaging tests)
• Complete blood count (CBC)
• Blood clotting tests
• Kidney and liver function tests

Treatment

If your provider suspects a molar pregnancy, removal of the abnormal tissue with a dilation and curettage (D&C) will most likely be suggested. D&C may also be done using suction. This is called suction aspiration (The method uses a suction cup to remove contents from the uterus).

Sometimes a partial molar pregnancy can continue. A woman may choose to continue her pregnancy in the hope of having a successful birth and delivery. However, these are very high-risk pregnancies. Risks may include bleeding, problems with blood pressure, and premature delivery (having the baby before it is fully developed). In rare cases, the fetus is genetically normal. Women need to completely discuss the risks with their provider before continuing the pregnancy.

A hysterectomy (surgery to remove the uterus) may be an option for older women who DO NOT wish to become pregnant in the future.

After treatment, your hCG level will be followed. It is important to avoid another pregnancy and to use a reliable contraceptive for 6 to 12 months after treatment for a molar pregnancy. This time allows for accurate testing to be sure that the abnormal tissue does not grow back. Women who get pregnant too soon after a molar pregnancy are at high risk of having another molar pregnancy.

Prognosis

Most HMs are noncancerous (benign). Treatment is usually successful. Close follow-up by your provider is important to ensure that signs of the molar pregnancy are gone and pregnancy hormone levels return to normal. About 15% of cases of HM can become invasive. These moles can grow deep into the uterine wall and cause bleeding or other complications. This type of mole most often responds well to medicines. In very few cases of complete HM, moles develop into a choriocarcinoma. This is a fast-growing cancer. It is usually successfully treated with chemotherapy, but can be life threatening.

Possible Complications Complications of molar pregnancy may include:

• Change to invasive molar disease or choriocarcinoma
• Preeclampsia
• Thyroid problems
• Molar pregnancy that continues or comes back

Complications from surgery to remove a molar pregnancy may include:

• Excessive bleeding, possibly requiring a blood transfusion
• Side effects of anesthesia

NIH genetic and rare disease info

• NIH info on Hydatidiform mole

Hydatidiform mole is a rare disease.

Hydatidiform mole Resources
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