The differential diagnosis of acute abdominal pain in pregnancy is broad and can be complicated by atypical manifestations that are due to the anatomic distortions and physiologic changes of pregnancy. Due to the lack of clinical understanding, angular pregnancy does not appear to be recognized as a clinical entity and many cases are likely to go undiagnosed. This is a case report of a 34-year-old woman who was referred to the obstetrics emergency department with sudden abdominal pain and in a state of hypovolemic shock. She had 20 weeks amenorrhea with a positive blood pregnancy test. She underwent laparatomy with internal hemorrhage diagnosis. During the emergency laparotomy, the authors were surprised to encounter the conceptus of 20 weeks angular pregnancy extruded through the left lateral angulation of uterine cavity. The placenta and amnion were removed and the uterine was repaired.