History and exam

Key diagnostic factors

common

first trimester of pregnancy

Women typically present in the first trimester of pregnancy with a history of a missed menstrual period.

Most molar pregnancies are diagnosed incidentally at pathologic evaluation of an evacuated dilation and evacuation (D&E) specimen for missed abortion, or from early maternal ultrasound screening in the first trimester of pregnancy.​[30][31]​​

vaginal bleeding

Vaginal bleeding is the most common presenting symptom of molar pregnancies (58% to 84%).[30][34]​​ This may vary in its degree from light spotting to heavy bleeding, and may include passage of hydropic villi. Heavy or persistent bleeding can lead to anemia.

unusual uterine size for gestational age

The uterine size is greater than expected for gestational age in approximately 25% of complete molar pregnancies.[36]​​[37]

However, the uterine size may be smaller than anticipated in partial molar pregnancies because of fewer hydropic villi and abnormal fetal development (e.g., slow growth of a fetus with triploidy).

Other diagnostic factors

uncommon

early-onset preeclampsia

Exacerbated signs and symptoms of preeclampsia such as hypertension, headache, and photophobia may be present before 20 weeks’ gestation (as a result of abnormally high serum human chorionic gonadotropin [hCG] levels).

Ophthalmopathy is absent.

shortness of breath and respiratory distress

High-output cardiac failure from hyperthyroidism, severe preeclampsia and, less commonly, anemia may lead to dyspnea and respiratory distress.

severe nausea and emesis

Women with complete hydatidiform moles report exacerbated symptoms of pregnancy (as a result of abnormally high serum hCG levels) that include severe nausea and emesis (hyperemesis gravidarum).[44]

tachycardia, tremor, insomnia, and diarrhea

There is molecular homology between subunits of thyroid-stimulating hormone and hCG. As a result, serum hCG may stimulate the production of thyroid hormone with the clinical symptoms and signs of thyrotoxicosis.[26][38]​​[39]

Ophthalmopathy is absent.

pallor

Anemia may result from heavy or persistent vaginal bleeding and the dilational effects of increased blood volume.

pelvic pain

Women with molar pregnancies may experience pelvic pain secondary to ovarian theca lutein cysts.

uterine bleeding

There may be active bleeding from the cervical os, and there may be spontaneous evacuation of hydropic vesicles from the cervix.​[4]

Risk factors

strong

extremes of maternal age

There is a significantly higher chance of MP among women over 35 years of age, which increases progressively as maternal age advances.[10][11][12][13]​ There is a modestly increased risk of MP among women with a maternal age of less than 20 years.[14][15]

prior molar pregnancy

Women with a previous diagnosis of hydatidiform mole have a 1% to 2% (or about 10 times the baseline) risk of a molar gestation in a subsequent pregnancy.[8][9]

weak

diminished dietary fat and carotene

It has been suggested that reduced dietary animal fat and carotene intake in certain geographic areas (e.g., Latin America and Southeast Asia) might account for the higher rate of MP in these populations.[27][28][29]​​

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