Am Fam Physician. 1999;59(3):649-651
A 14-year-old (gravida 1, para 0) Asian female at approximately 16 weeks' gestation presented to the office with a fever and a small amount of painless vaginal bleeding of one day's duration. She had received no prenatal care. Her uterus was mildly tender on palpation and was determined to be approximately 18 weeks in size. Sterile speculum examination revealed approximately 10 mL of non-clotted blood in the vaginal vault and a closed internal os. A transabdominal ultrasound examination was performed, and the result is shown in Figure 1.
Question
Which one of the following is the correct diagnosis, based on the patient's history, physical examination and ultrasound examination?
Discussion
The answer is D: hydatidiform mole. The ultrasound image on the previous page shows the characteristic vesicular pattern of the molar pregnancy, which is sometimes referred to as a “snowstorm” pattern. The patient had a human chorionic gonadotropin (HCG) level greater than 160,000, further supporting the clinical diagnosis. The fever was presumed to be due to intrauterine infection of the mole. The patient was given intravenous antibiotics and a dilation and evacuation was performed. Figure 2 shows the gross specimen from the procedure. Note the hydropic swelling and typical grape-like appearance of the chorionic villi.
Molar pregnancies are reported to occur in approximately one in 1,000 pregnancies.1 The risk is higher in teenagers and women older than 35 years.2,3 In addition, certain populations seem to be at higher risk. Results from an Indonesian study2 determined that the incidence in that population is one in 100 pregnancies. Previous miscarriage also increases the risk. In one study,4 the risk of molar pregnancy increased by a factor of 32 after two consecutive miscarriages.
Vaginal bleeding is the most common presenting symptom. Hyperemesis and preeclampsia are less frequent presentations. Mean gestational age at diagnosis varies from 12 to 17 weeks, depending on the availability and use of ultrasonography or quantitative HCG levels, or both.3 Uterine enlargement is typically more rapid than expected, and quantitative HCG levels are usually much higher than the levels found in a normal pregnancy of similar gestational age. Complete, or classic, moles have no identifiable fetal tissue, while partial moles usually contain some recognizable fetal or embryonic tissue.
It is important to recognize molar pregnancies because they are potential precursors to gestational trophoplastic disease or choriocarcinoma, which can metastasize to the lungs, vagina, brain, liver or kidney.2 Hyperthyroidism, respiratory distress and anemia are potential medical complications. Treatment includes evacuation and curettage, or hysterectomy, depending on the age of the patient and her desire to preserve fertility. βHCG should be tested weekly until the titer is within normal limits for three weeks and then should be drawn monthly for six to 12 months.5 The patient who is Rh-negative should receive Rh-immunoglobulin. Effective contraception must be used during the entire follow-up period of at least one year.1 The patient who has had a hydatidiform mole should be reassured that only 1 percent of subsequent conceptions result in another molar pregancy.6
Of the remaining possible diagnostic choices, placenta previa is important to consider when a pregnant woman presents with painless vaginal bleeding. A patient with a missed abortion could certainly present with fever and vaginal bleeding. However, the absence of any identifiable fetal parts on ultrasound examination essentially rules out these diagnostic choices.