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BCM - Baylor College of Medicine

Giving life to possible

Obstetrics and Gynecology

Gestational Trophoblastic Disease - GTD (including Molar Pregnancy)

Gestational trophoblastic disease (GTD) is a rare group of diseases that develop in the uterus during an abnormal pregnancy. It occurs when abnormal cells or tumors grow in the tissues that are formed following conception that would normally surround the embryo and develop into the placenta.

The tumors are referred to as "moles."

Most GTDs are benign, or noncancerous, however some forms may develop into cancer and spread to other parts of the body.

All forms of the disease can be treated and in most cases cured.

What causes gestational trophoblastic disease or a molar pregnancy?

While the exact cause is not known, factors that may increase a woman's risk of having a molar pregnancy include:

  • Becoming pregnant before age 20 or after age 40
  • Race - Asian women are at increased risk
  • Prior history of gestational trophoblastic disease
  • Dietary deficiencies

The main types of gestational trophoblastic disease are:

Hydatidiform mole. The most common form, also called a molar pregnancy, occurs when the sperm and egg cells join but do not develop into a fetus. Instead, tissue forms that resembles small clusters of grapes. These moles are not cancerous, but they may develop into cancerous GTDs.

Invasive mole.  A hydatidiform mole that has grown into the muscle layer of the uterus

Choriocarcinoma. A cancerous tumor that develops from a hydatidiform mole, or from tissue that remains in the uterus following an abortion, miscarriage or delivery. Choriocarcinoma can grow quickly and spread from the uterus to other parts of the body.

Placental-site trophoblastic tumor. A very rare form of GTD that develops where the placenta attaches to the lining of the uterus, usually after a normal pregnancy or an abortion. These tumors may invade the muscle layer of the uterus.

What are the symptoms of gestational trophoblastic disease or a molar pregnancy?

Symptoms vary based on the type of GTD but may include:

  • Unusual abdominal swelling
  • Unusual vaginal bleeding during pregnancy
  • Severe nausea
  • Severe vomiting
  • Anemia
  • Overactive thyroid gland
  • No fetal movement or heartbeat

How is gestational trophoblastic disease diagnosed?

In addition to a thorough medical history and physical exam, diagnosis may include:

  • Pelvic exam - to feel for any lumps or abnormalities
  • Ultrasound - to look for tumors
  • Blood test - to look for high levels of hCG (human chorionic gonadotropin), a hormone present during normal pregnancy

How is gestational trophoblastic disease treated?

Treatment depends on the individual patient, the type of tumor and whether it has spread, but may include:

  • Surgery - to remove the cancer, typically either a dilation and curettage (D&C) procedure, which involves gently scraping or suctioning the walls of the uterus, or a hysterectomy to remove the uterus
  • Chemotherapy - the use of drugs giving intravenously (into the vein) to destroy cancer cells
  • Radiation therapy - the use of high-energy X-rays to kill cancer cells and shrink tumors