What is this Condition?

Hydatidiform mole is an uncommon chorionic tumor of the placenta. Its early signs - absence of menstrual periods and an enlarged uterus - mimic those of normal pregnancy; however, it eventually causes vaginal bleeding. Hydatidiform mole occurs in 1 in 1,500 to 2,000 pregnancies, most commonly in women over age 45. Incidence is highest in Asian women.

With prompt diagnosis and appropriate treatment, the prognosis is excellent. However, approximately 10% of women with this disorder develop chorionic cancer. Recurrence is possible in about 2% of cases.

What Causes it?

The cause of hydatidiform mole is unknown, but death of the embryo and loss of fetal circulation seem to precede it. Despite the embryo’s death, maternal circulation continues to nourish the trophoblast (tissue surrounding the embryo), but loss of fetal circulation causes abnormal fluid buildup within the villi. This converts some or all of the chorionic villi into a mass of clear vesicles, resembling a bunch of grapes.

What are its Symptoms?

The early stages of this type of pregnancy typically seem normal, except that the uterus grows more rapidly than usual. The first obvious signs of trouble - absence of fetal heart tones, vaginal bleeding (ranging from spotting to hemorrhage), and lower abdominal cramps - mimic those of a miscarriage. The blood may contain hydatid vesicles; excessive vomiting is likely, and signs and symptoms of preeclampsia are possible. Other possible complications of hydatidiform mole include anemia, infection, miscarriage, uterine rupture, and choriocarcinoma.

How is it Diagnosed?

Persistent bleeding and an abnormally enlarged uterus suggest hydatidiform mole. Diagnosis is based on the passage of hydatid vesicles, which allows microscopic confirmation. Without identification of hydatid vesicles, it’s difficult to differentiate hydatidiform mole from other complications of pregnancy, particularly an impending miscarriage. Confirmation of hydatidiform mole requires a dilatation and curettage (called a D & C).

The diagnosis may also be supported by ultrasound studies, a pregnancy test, arteriography, chest X-ray (to rule out types of cancer), and other lab tests.

How is it Treated?

Hydatidiform mole requires uterine evacuation by D & C, abdominal hysterectomy, or instrument or suction curettage, depending on the size of the uterus. Intravenous Pitocin may be used to promote uterine contractions. Because this drug may act as an antidiuretic, the woman must be observed for respiratory complications.

Postoperative treatment varies, depending on the amount of blood lost and complications. If no complications develop, hospitalization is usually brief and normal activities can be resumed quickly.

Because of the possibility of choriocarcinoma developing after hydatidiform mole, scrupulous follow-up care is essential. Such care includes monitoring human chorionic gonadotropin levels until they return to normal and taking chest X-rays to check for cancer spread to the lungs. Another pregnancy should be postponed until at least 1 year after hormone levels return to normal.

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