Tubal ectopic pregnancies are commonly diagnosed during the first trimester. Here we present a second-trimester tubal ectopic pregnancy that was previously misdiagnosed as an intrauterine pregnancy on a first-trimester ultrasound. A 39-year-old gravida 1 para 0 woman at 15 weeks gestation presented with 10 days of progressive, severe abdominal pain, along with vaginal bleeding and intermittent vomiting for two months. She was ultimately found to have a ruptured left tubal ectopic pregnancy. Second-trimester ectopic pregnancies carry a significant maternal mortality risk. Even with the use of ultrasound, they are difficult to diagnose and present unique diagnostic challenges.