Hydatidiform mole

Hydatidiform mole (H. mole) is one of a spectrum of diseases classified as a Gestational Trophoblastic Disease. Gestational trophoblastic disease encompasses several disease processes that originate in the placenta. These include complete and partial moles, invasive moles, placental site trophoblastic tumors, and choriocarcinomas.

Hydatidiform mole is a relatively complication of pregnancy. Incidence is about 1 in 1000 pregnancies in the United States and other western countries, but in the Philippines as well as other Asian countries, the incidence is much higher, closer to about 1 in 100 pregnancies.

Types:

Hydatidiform moles are usually classified as complete or partial moles. These are usually benign uterine masses, but they do have a slight chance of converting to malignancy.

In a complete mole, there is no identifiable fetal tissue, unlike in a partial mole, wherein there may be an abnomal fetus or other elements like placental tissue.

Other gestational trophoblastic diseases which must be differentiated are invasive moles and choriocarcinoma.

Etiology and Risk factors:

The etiology of this condition is not completely understood.

Potential risk factors may include the following:

- defects in the egg

- abnormalities within the uterus

- nutritional deficiencies: diets low in protein, folic acid and carotene

- age: Women under 20 or over 40 years of age have a higher risk.

Signs and Symptoms:

The most common complaint of patients with H. mole is painless vaginal bleeding. The patient may also experience nausea and vomiting, as well as other signs of pregnancy. The uterus may also be noted to enlarge, mimicking a normal pregnancy. There may also be symptoms of hyperthyroidism, since large amounts of Beta HCG in the blood may mimic thyroid stimulating hormones (TSH).

Diagnosis:

A urine pregnancy test may turn out to be positive because of the high levels of circulating human chorionic gonadotrophin (HCG) hormone, although there may also be cases wherein a false negative pregnancy test may also appear. A more accurate baseline would be a serum (blood) determination of the beta component of HCG (Beta HCG). Levels of Beta HCG are higher than what would be expected for a normal pregnancy of equal duration. This test, although highly suggestive of a gestational trophoblastic disease (GTD), is not definitive for any of GTDs.

A transvaginal ultrasound is usually ordered by the obstetrician gynecologist to check for the presence and characteristic of the uterine mass. The definitive diagnosis, however is via a biopsy.

Chest x-rays and abdominal ultrasounds are usually done to check for any metastasis of villous tissue, as this would affect both the diagnosis (H mole vs. invasive mole vs. choriocarcinoma) and the treatment. Blood exams are usually done prior to treatment to check for liver and kidney functions in preparation for possible chemotherapy treatment. A complete blood count, blood typing, and platelet count is usually done in preparation for blood transfusion.

Treatment:

Suction curettage is the treatment of choice to remove a hydatidiform mole. Since blood loss is expected during the surgery, compatible blood is usually prepared beforehand, typed and crossmatched, so that a transfusion may be done before, during or after surgery, as dictated by the findings.

Specimens obtained during the procedure are sent to the histopathology lab for a the definitive histopathologic diagnosis (Biopsy).

Depending on the associated finding, the gynecologist may also decide to give a course of chemotherapy with low dose Methotrexate (or other chemotherpeutic agents) as prophylaxis against malignant conversion or invasion.

It is important for the attending gynecologist to have a high index of suspicion regarding the mass. The levels of the serum beta HCG and the ultrasound findings would give a strong suggestion of the type of GTD, whether it is an H. mole, an invasive mole or a choriocarcinoma. This is because the treatment protocols of each disease in the spectrum is different.

Follow up:

Serum Beta HCG levels are monitored biweekly after suction curettage until the level reaches undetectable levels. If the beta HCG levels remain high or spikes after it has already decreased, additional therapy may be required.

Patient is advised not to get pregnant within 1 year because of the following reasons:

- Pregnancy increases HCG levels, which would make monitoring of any recurrence difficult.

- A new pregnancy episode may trigger a recurrence of H. mole.

Prognosis:

Prognosis for H mole is usually very good. 80% do not result in malignant conversion. Of the 20% who do develop malignancy, chemotherapy usually works in most cases.

Chance of recurrence is about 1%.

A previous H mole does not affect the chances for a future normal pregnancy. The normal risk factors still apply, though.

Disclaimer: Contents of this blog is only intended as a simplified guide. It is still best to consult an obstetrician-gynecologist if you suspect or are diagnosed with this problem.