Molar pregnancy is part of a spectrum of gestational trophoblastic tumors that include benign hydatidiform moles, locally invasive moles, and choriocarcinoma. The classic clinical presentation is painless first-trimester or early second-trimester vaginal bleeding with a uterine size larger than the estimated gestational age based on the last menstrual period. Signs of preeclampsia (hypertension, headache, proteinuria, and edema) in the 1st trimester or early 2nd trimester are highly suggestive of this diagnosis as well. Hyperthyroidism is found in roughly 5% of cases. Acute respiratory distress may occur due to embolization of trophoblastic tissue into the pulmonary vasculature, thyrotoxicosis, or simple fluid overload.
Molar Pregnancy. “Snowstorm” pattern demonstrating multiple intrauterine echoes with no fetus seen on transvaginal ultrasonography in a patient with a molar pregnancy. Serum β-hCG was greater than 180,000 mIU/mL. (Photo contributor: Robin Marshall, MD.)
Management and Disposition
Obtain gynecologic consultation for dilatation and curettage in all cases. Close monitoring of serum hCG levels is required to rule out the presence of malignant gestational trophoblastic disease.
All patients with pregnancies of less than 20 weeks’ gestation with clinical findings of preeclampsia should be considered to have gestational trophoblastic disease until it is ruled out.
A “snowstorm” pattern on ultrasonography (demonstrating multiple intrauterine echoes with no fetus) coupled with a high hCG level is typical of molar pregnancy. Molar pregnancies may also resemble a “cluster of grapes” on US.
“Moles” commonly produce serum hCG levels greater than 100,000 mIU/mL.
Molar Pregnancy. Transabdominal study showing molar pregnancy. These are exceedingly difficult to identify and diagnose by ultrasound. They can be easily mistaken for nonspecific intrauterine findings (eg, missed abortion, fibroid). (Photo contributor: Lauren Oliveira, DO.)