A 41-year-old woman comes to the emergency department for heavy vaginal bleeding. Her last normal menstrual period was 4 months ago, but she has had irregular spotting since. Earlier today, the patient began to have increasingly heavy vaginal bleeding with passage of small clots. She also has had increasing hot flashes, night sweats, and palpitations over the past 3 weeks but no chest pain, shortness of breath, or orthopnea. The patient had a Roux-en-Y gastric bypass 7 years ago and has lost 45 kg (99 lbs) since. Temperature is 37.7 C (99.9 F), blood pressure is 150/90 mm Hg, and pulse is 118/min. BMI is 35 kg/m². Physical examination shows her to be anxious. The skin is warm and smooth. Cardiac examination reveals tachycardia but a regular rhythm; there are no rubs or murmurs. The lungs are clear to auscultation bilaterally. Pelvic examination shows a moderate amount of blood in the vaginal vault and a closed cervix. Bimanual examination is limited by the patient's obesity but reveals an enlarged uterus. Bedside pelvic ultrasound reveals an enlarged uterus filled with a heterogeneous mass composed of small, cystic structures. TSH is 0.1 µU/mL. Serum β-hCG level is elevated. Which of the following is the most likely diagnosis in this patient?

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11ec25c8_da35_ab40_bc81_a99b6d3536a5_MD0003_00 This patient's presentation of heavy vaginal bleeding (due to passage of hydropic villi), overt hyperthyroidism, elevated β-hCG, and an enlarged uterus with a heterogeneous cystic mass is concerning for a hydatidiform mole (HM). Risk factors for HM include vitamin A deficiency (eg, Roux-en-Y surgery) and extremes of maternal age. Patients age >40 with HM are also at risk for more severe complications. An HM is a nonviable, abnormal gestation composed of hypertrophic and hydropic placental trophoblastic villi. The trophoblastic hypertrophy leads to markedly elevated hCG levels. On ultrasound, the hydropic trophoblasts appear as a heterogeneous mass of cystic spaces, described as having a "snowstorm" appearance. "snowstorm" appearance As hCG (both α and β subunits) and TSH have a similar structure, elevations in hCG can mimic TSH and cause an increase in triiodothyronine (T3) and thyroxine (T4) concentrations. The markedly elevated hCG levels associated with HM can therefore cause overt hyperthyroidism (eg, hot flashes, tachycardia, smooth warm skin, low TSH) as seen in this patient. These complications resolve after treatment as the hCG level decreases and the T3 and T4 levels normalize. (Choice A) An ectopic pregnancy typically presents with unilateral pelvic pain and vaginal bleeding. Ultrasonography reveals an empty uterus and an adnexal mass. (Choice B) Embryonal carcinoma, an ovarian cancer that is typically diagnosed in adolescents, secretes hCG. Embryonal carcinoma typically presents with abdominal pain and an adnexal mass on ultrasound but not with vaginal bleeding. (Choice C) Endometrial cancer can present with abnormal vaginal bleeding, but ultrasound reveals a thickened endometrial lining rather than a heterogenous cystic intrauterine mass. There is no association between endometrial cancer and an elevated hCG level or hyperthyroid state. (Choice E) An inevitable abortion presents with vaginal bleeding, a dilated cervix, and an ultrasound revealing an intrauterine gestation in the lower uterine segment. (Choice F) Polycystic ovarian syndrome presents with anovulatory oligomenorrhea, elevated serum testosterone levels, an undetectable hCG level, and an ultrasound that reveals multiple, small ovarian cysts. (Choice G) Sarcoma botryoides (eg, embryonal rhabdomyosarcoma) typically presents in infancy and early childhood as nonfriable nodules protruding from the vagina that look like a cluster of grapes. hCG is negative in these patients. Educational objective: A hydatidiform mole, a type of gestational trophoblastic disease, can present with vaginal bleeding, overt hyperthyroidism, and a markedly elevated hCG level. Ultrasound findings include an enlarged uterus filled with a heterogeneous, multicystic mass. References: Gestational trophoblastic disorders: an update in 2015. (http://www.ncbi.nlm.nih.gov/pubmed/26556906)

A 41-Year-Old Woman Comes to the Emergency Department for Heavy