An interstitial pregnancy is a rare type of ectopic pregnancy located within the proximal portion of the fallopian tube in the muscular wall of the uterus. They are more likely to result in significant or fatal hemorrhage because of the increased vascularity. Diagnosis of interstitial pregnancy is challenging but critical to facilitate prompt and appropriate intervention. Ultrasound performed by an emergency physician is commonly used to assess early pregnancy, but little has been published in the emergency medicine literature regarding its use in assessing for presence of interstitial pregnancy. We describe a case of a ruptured interstitial pregnancy diagnosed by emergency ultrasonography in the emergency department and review the literature regarding the sonographic findings of interstitial pregnancies.