RESUMEN
BACKGROUND: Diagnosis of ectopic pregnancy can be complicated by nonspecific laboratory and radiographic findings. The multiple alternative diagnoses must be weighed against each other based on the entire clinical presentation. CASE REPORT: We present a case of a 20-year-old woman who arrived to the Emergency Department (ED) with abdominal pain and ended up being transferred for an Obstetrics evaluation of a possible heterotopic pregnancy. Her radiology-performed ultrasound had revealed an "intrauterine gestational sac" along with an adnexal mass near the right ovary. The patient was not undergoing assisted-reproductive fertilization, nor did she have meaningful risk factors for heterotopic pregnancy. The patient was managed expectantly over the ensuing week to see whether the intrauterine fluid was a true gestational sac. After multiple repeat ED visits, the diagnosis of ectopic pregnancy was made. Ultimately, the patient elected for surgical management of her ectopic pregnancy. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case offers a reminder of the subtleties of radiographic identification of intrauterine pregnancies and the ever-present need to "clinically correlate."