Heterotopic pregnancies are a rare phenomenon defined by the simultaneous occurrence of intrauterine and extrauterine pregnancy. The incidence of heterotopic pregnancy occurring through natural fertilization is low but is increased by risk factors such as assisted reproductive techniques or pelvic inflammatory disease increase. We report the case of a 36-year-old female patient in the 6th week of pregnancy who presented to the emergency unit with severe acute lower abdominal pain. Laboratory chemistry and sonography revealed a suspected heterotopic pregnancy. The patient was admitted for observation. The sonographic reevaluation on the next day confirmed the suspicion of extrauterine gravidity with intact intrauterine gravidity with additional decreasing hemoglobin and hematoperitoneum, so that laparoscopy was indicated. Intraoperatively, the mass on the left ovary was removed without complications. The patient could be discharged quickly postoperatively after a complication-free course and gave birth to a healthy child by spontaneous partus in the 38th week of gestation. Due to their rarity, there is limited research related to heterotopic pregnancies, and most scientific articles are case studies. Diagnostically, the most important thing in clinical practice is to think about the possibility of EUG even if there is evidence of an intact IUG. Transvaginal sonography is of particular importance in diagnostics. The performance of prospective cohort studies is desirable for the evidence-based diagnosis and therapy of affected patients in the future.