Case
A 26-year-old gravida 3, para 2-0-0-2, aborta 0 whose last menstrual period was 15 weeks 5 days, presented to the ED with complaints of mild vaginal spotting, which she first noted postcoitally the previous day. The patient denied fatigue, lightheadedness, dyspnea, abdominal pain, nausea, or vomiting.
Physical examination revealed a well-appearing patient with normal vital signs. The abdomen was soft and nontender, and the fundus was palpable at the level of the umbilicus. A speculum examination was unremarkable, with normal external genitalia, a closed cervical os, no adnexal masses or tenderness, and no blood in the vaginal vault. Laboratory studies were significant for a serum beta human chorionic gonadotropin (beta-hCG) of 7,442 mIU/mL (reference range for 15 weeks: 12,039-70,971 mIU/mL). The patient was Rh positive with a stable hematocrit.
A bedside ultrasound, performed by an ultrasound-]trained emergency physician (EP), was noted to demonstrate a complex intrauterine mass comprised of several small, rounded anechoic clusters (Figure).
An obstetric consultation was made and the patient was taken to the operating room the following day for a dilation and curettage (D&C) procedure. She was discharged home the next day without complications. The products of conception were sent to pathology, and confirmed a triploid karyotype and p57 trophoblastic immunopositivity, diagnostic of a partial hydatidiform mole.
Discussion
Hydatidiform moles are a subset of abnormal pregnancies termed gestational trophoblastic disease (GTD). The two greatest risk factors for GTD are previous GTD and extremis of maternal age.1 Patients often present to the ED because of painless heavy vaginal bleeding, hyperemesis gravidarum, symptoms of hyperthyroidism, or preeclampsia before 20 weeks.2 Clinically, these patients present with an enlarged uterus for gestational age and very high beta-hCG levels, often greater than 100,000 mIU/mL.3 The high beta-hCG levels can lead the patient to present with symptoms of hyperthyroidism, such as severe hypertension, given the similar chemical structures of beta-hCG and thyroid-stimulating hormone.4
After a D&C, interval beta-hCG levels need to be obtained to ensure resolution. A patient with beta-hCG levels that do not fall by 10% after 3 weeks, or are still present after 6 months, should be referred to a gynecologic oncologist.5,6 Furthermore, a chest X-ray is strongly suggested, as the lungs are often the first place of metastasis.7
Partial hydatidiform moles are formed by a dispermic fertilization of a normal ovum leading to a triploid pattern, and are clinically distinguished from complete molar pregnancies because affected patients have a uterus that is often small for gestational age.8 Also, while the beta-hCG is also abnormally elevated, the median value is more modest at approximately 50,000 mIU/mL.3
According to the American College of Radiology’s Appropriateness Criteria, ultrasound is the gold standard for evaluating gestational trophoblastic disease. While the classic sonographic appearance of a molar pregnancy is described as a “snowstorm” appearance, advancement in technology more clearly demonstrates a “cluster of grapes” or “honeycomb” appearance.9 On Doppler mode, increased vascularity peripherally can also be detected due to engorgement of the spiral arteries. While partial moles tend to have more focal lesions, the greatest distinguishing factor is the presence of embryonic or fetal tissue, which is not seen in complete moles. However, due to the heterogeneous appearance of the uterus in all GTD, molar pregnancies can sometimes be misinterpreted as missed abortions or clotted blood, so that pathological confirmation is mandatory for all products of conception in the United States and Canada.2,10
Summary
This case is of particular interest because it demonstrates an atypical presentation of a partial hydatidiform mole. While most classic presentations include older patients with heavy vaginal bleeding, a smaller uterus than expected, significantly elevated beta-hCGs, and hyperemesis gravidarum, our patient was relatively young with no history of molar pregnancies in the past, a larger-than-expected uterus, and no vaginal bleeding noted. Laboratory values also indicated a significantly lower-than-expected beta-hCG level. As such, bedside ultrasound findings were unexpected but resulted in the prompt diagnosis, an emergent obstetric consultation, and confirmatory radiology imaging. The ED bedside ultrasound findings did demonstrate the characteristic “cluster of grapes” appearance surrounded by the hyperechoic appearance of the spiral arteries (Figure). An intrauterine yolk sac was also identified by ultrasound, which strongly suggested a partial rather than a complete hydatidiform molar pregnancy.