Managing molar pregnancy

Key Points

Case 1. Complete hydatidiform mole

A 37-year-old Asian woman (gravida 2, para 1) presented at 16.5 weeks' gestation with a "prune juice" discharge, severe nausea, and a 22-week-sized uterus. Initial blood work revealed a beta-human chorionic gonadotropin (hCG) level of 1.5 million IU/L, hematocrit of 29%, and T4 level of 15 mcg/dL. Her blood type was O Rh negative. The patient was mildly hypertensive, with 1+ pitting edema bilaterally and 1+ proteinuria. Ultrasound revealed the characteristic vesicular pattern consistent with the diagnosis of complete hydatidiform mole. Both ovaries were enlarged and cystic. A preoperative chest x-ray was negative. An uncomplicated suction evacuation was carried out under general anesthesia after administration of a beta-blocking agent. Rh immune globulin was administered in the recovery room. While en route to the recovery room, the patient developed dyspnea. Auscultation of the lungs revealed diffuse rales. Nasal oxygen was required to maintain a satisfactory pO2. Portable chest x-ray showed diffuse infiltrates bilaterally. The patient's dyspnea and chest findings cleared in 48 hours.

The final pathologic diagnosis confirmed a complete hydatidiform mole. Transient enlargement of the ovaries during the first few weeks after evacuation caused abdominal distension and mild shortness of breath. The beta-hCG level was followed weekly and became undetectable after 10 weeks. The patient expressed a desire to become pregnant as soon as possible.

The clinical presentation of complete mole has changed significantly over the past 2 decades.

Before the widespread use of ultrasound in early pregnancy, most patients with a classic complete mole presented with vaginal bleeding in the second trimester at a mean gestational age of 16.5 weeks.¹

In addition to uterine bleeding, the classic presenting signs and symptoms included anemia, excessively enlarged uteri, prominent theca lutein cysts, preeclampsia, hyperemesis, hyperthyroidism, and respiratory failure. Serum beta-hCG levels in most patients were greater than 100,000 IU/L because of the presence of hyperplastic trophoblasts.

The diagnosis of complete mole is now typically made in the first trimester, usually before classic signs and symptoms develop.^1,2 Vaginal bleeding is still the most common presenting symptom, seen in 84% of cases. The mean gestational age at diagnosis is now 11.8 weeks. The classic signs and symptoms are infrequently encountered.

Complete moles usually have a 46XX karyotype, and the molar chromosomes are derived completely from the father. Most complete moles are homozygous and arise from an anuclear empty ovum that has been fertilized by a haploid (23X) sperm, which then replicates its own chromosomes. The mitochondrial DNA, however, has a maternal origin.⁴

In contrast, the pathologic features of early complete moles are less readily identifiable, making the pathologic diagnosis more challenging. Early complete moles have subtle morphologic features including smaller villi and less trophoblastic hyperplasia that may lead to their misclassification as partial moles or nonmolar abortions.