Molar pregnancy & its possible medical complications

A molar pregnancy which is also known as hydatidiform mole is a rare complication of pregnancy characterised by the abnormal growth of trophoblasts, the cells that normally develop into the placenta.

There are two types of molar pregnancy, complete molar pregnancy and partial molar pregnancy. In a complete molar pregnancy, the placental tissue is abnormal and swollen and appears to form fluid-filled cysts. There’s also no formation of fetal tissue. In a partial molar pregnancy, there may be normal placental tissue along with abnormally forming placental tissue. 

There may also be formation of a fetus, but the fetus is not able to survive, and is usually miscarried early in the pregnancy.

Symptoms

A molar pregnancy may seem like a normal pregnancy at first, but most molar pregnancies cause specific symptoms, including:

• Dark brown to bright red vaginal bleeding during the first trimester of pregnancy
• Severe nausea and vomiting
• Sometimes vaginal passage of grape like cysts
• Pelvic pressure or pain

Risk factors

Approximately 1 in every 1,000 pregnancies is diagnosed as a molar pregnancy. Various factors are associated with molar pregnancy, including:

• Maternal age. A molar pregnancy is more likely in women older than age 35 or younger than age 20.
• Previous molar pregnancy. If you’ve had one molar pregnancy, you’re more likely to have another. 

Complications

A molar pregnancy can have serious complications including a rare form of cancer and requires early treatment. 

After a molar pregnancy has been removed, molar tissue may remain and continue to grow. This is called persistent gestational trophoblastic neoplasia (GTN). This occurs in about 15% to 20% of complete molar pregnancies, and up to 5% of partial molar pregnancies.

Rarely, a cancerous form of GTN known as choriocarcinoma develops and spreads to other organs. Choriocarcinoma is usually successfully treated with multiple cancer drugs. A complete molar pregnancy is more likely to have this complication than a partial molar pregnancy.

Prevention

During any subsequent pregnancies, your care provider may do early ultrasounds to monitor your condition and offer reassurance of normal development. Your provider may also discuss prenatal genetic testing, which can be used to diagnose a molar pregnancy.