Molar Pregnancy

A molar pregnancy occurs when a fertilized egg develops into a tumor that grows within the uterus. In a molar pregnancy, the egg is abnormally fertilized and contains an extra set of paternal chromosomes, but no chromosomes from the mother. As a result, instead of a healthy fetus developing, a tumor forms. Also referred to as a hydatidiform mole, this abnormal growth of tissue may result in a partial or complete molar pregnancy. With a partial molar pregnancy, there is abnormal fetal and placenta development, however the embryo is malformed and unable to survive. In a complete molar pregnancy, there is no fetal development, only abnormal placental tissue.

Symptoms of a Molar Pregnancy

The initial symptoms of a molar pregnancy are the same as those of a normal pregnancy: a missed period, sore breasts, mild cramping. However additional symptoms soon develop which may include:

  • Severe nausea and vomiting
  • Vaginal bleeding during the first trimester
  • Vaginal passage of cysts
  • Abnormal uterine growth
  • High blood pressure

If a molar pregnancy is present, women may also experience symptoms of hyperthyroidism.

Diagnosis of a Molar Pregnancy

If a molar pregnancy is suspected, the physician performs a pelvic examination and a pelvic ultrasound. The ultrasound can help to confirm the absence of an embryo or fetus as well as any abnormalities within the uterus. A blood test will also be administered to measure the level of the pregnancy hormone, human chorionic gonadotropin (HCG) in the blood. Kidney and liver function tests may also be administered.

Treatment of a Molar Pregnancy

If a molar pregnancy is confirmed, the pregnancy is not viable, so the tissue must be removed from the uterus. A procedure called a dilation and curettage (D&C) is performed. During this procedure the patient is sedated under anesthesia and the physician dilates the cervix and uses a vacuum device to remove the molar tissue from the uterus. In severe cases when the there is excessive molar tissue, a hysterectomy may be necessary. In addition, the HCG levels within the blood are monitored to make sure that there is no remaining molar tissue and that the tissue does not grow back. Women are advised to wait at least one year after a molar pregnancy before trying to conceive again.

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