Heterotopic Pregnancy: A Difficult and Rarely Considered Diagnosis.

A 34-year-old pregnant female presented to the emergency department (ED) with complaints of abdominal pain and vaginal bleeding for two days. The day prior, she was evaluated by her obstetrician and gynecologist with a transvaginal ultrasound demonstrating an intrauterine pregnancy at approximately six weeks gestation. After treatment of symptoms and reassuring laboratory testing, she went home. However, she returned two days later with worsening complaints. It was discovered that the patient had a heterotopic pregnancy, or a concomitant intrauterine and extrauterine pregnancy, resulting from natural conception in the absence of identifiable risk factors. While exceedingly rare, this diagnosis is frequently missed and associated with significant maternal morbidity and mortality if unrecognized.