Notes

The incidence of molar pregnancy is approximately 1 per 1,500-2,000 pregnancies among Caucasians in the United States. There is a much higher incidence among Asian women in the United States (1/800.) The risk of having a molar pregnancy is increased in women with two or more miscarriages.
The recurrent risk for molar pregnancies ranges from 1 to 2%, which is a 20-fold increase from background risk. The risk of recurrence after two molar pregnancies is 10%.
A complete mole has a characteristic “snowstorm” appearance on ultrasound. This is due to the presence of multiple hydropic villi. This patient has a classic presentation for a molar pregnancy. Vaginal bleeding is universal in molar pregnancies. Uterine size greater than dates (weeks from LMP) can be seen in 25-50% of moles, although size less than dates can be seen in 14-33% of moles. There is no fetus seen in cases of a complete mole. There can be a fetus, which is usually grossly abnormal, in cases of a partial mole. There is detectable Beta-hCG in molar pregnancies. The Beta-hCG values are generally higher than the values observed in normal pregnancy. Tachycardia from hyperthyroidism (10% serum diagnosis; 1% clinical diagnosis) and hypertension from preeclampsia (12-25%) can occur in molar pregnancy.
With a Beta-hCG above the discriminatory zone (>1500 mIU), an IUP should be easily identified on transvaginal ultrasound. If an IUP is not seen, the ultrasound findings (in conjunction with the Beta-hCG level) should identify a mole (multiple internal echoes) or an ectopic (absence of intra-uterine gestation).
Suction curettage is the standard management for molar pregnancies.
*****Molar pregnancies are classified as either complete or partial, depending on several histologic, pathologic and genetic characteristics. Partial moles may contain fetus/fetal parts, placenta/cord; complete moles do not. Partial moles are triploid karyotype (usually 69XXY, 69XXX, or 69XYY) resulting from fertilization of egg by dispermy; complete moles are diploid resulting from fertilization of “empty egg” by single sperm (46XX, 90%) or by two sperm (X & Y = 46XY 6-10%). Partial moles show marked villi swelling; complete moles show trophoblastic proliferation with hydropic degeneration "snowstorm". Clinically, partial moles present with lower Beta-hCG levels, affect older patients, have longer gestations, and are often diagnosed as missed or incomplete abortions. Complete moles usually present with larger uteri, preeclampsia and higher likelihood of developing into post-molar GTD (gestational trophoblastic disease).******
This patient most likely has metastatic GTD given the constellation of findings, and elevated Beta-hCG with no evidence of an intrauterine pregnancy. Although evacuation is likely necessary, the finding of a vaginal nodule raises the suspicion of metastasis and further warrants a full staging evaluation with a CT scan of the chest, abdomen and pelvis. A brain MRI is also likely. A simple CXR would not be sufficient since she already has evidence of metastasis to the vagina. Since metastatic GTD is known to be quite vascular, suspicious lesions should not be biopsied.
The constellation of findings described in this patient (large uterus, theca lutein cysts, high Beta-hCG) increases the risk that this molar pregnancy will persist despite complete evacuation, hence the need for close follow-up with serial Beta-hCG levels for at least 6 weeks before another pregnancy attempt. Persistent disease can easily be cured with chemotherapy, if it develops, and is therefore not routinely given prophylactically, except in high-risk situations (e.g. non-compliant patient who will be lost to follow-up).
***A diagnosis of GTD (choriocarcinoma) is made once the presence of Beta-hCG is confirmed following a pregnancy with mets to other parts of body. Because metastatic choriocarcinoma is quite vascular, suspicious lesions should never be biopsied. Tissue diagnosis is the standard in establishing a diagnosis of almost all malignancies, with the exception of choriocarcinoma. Only a positive Beta-hCG in a reproductive-aged woman who has a history of a recent pregnancy (term, miscarriage, termination, mole) is necessary to establish the diagnosis.***