Introduction: Heterotopic pregnancy occurs when intrauterine and ectopic implantation happens simultaneously. This type of pregnancy is extremely rare and the incidence is about 1 in 100 to 1 in 30000 of pregnancy. However, a heterotopic pregnancy usually occurs after using assisted reproductive technology, their occurrence in natural cycles is extremely rare.

Case report: A 28- year- old woman with prior term pregnancy was referred to the hospital  with complain of acute abdominal pain .She had no history of infertility and was a known case of polycystic  ovarian syndrome. Every day she used  a tablet  of metformin  from 1 month  ago.

Heterotopic pregnancy were diagnosed in 8 week plus 4 days of gestation by using the titrate

Of BHCG and serial sonography and the fetus in the uterine cavity was missed. Laparotomy were Performed and a ruptured ampullary ectopic gestation was present in left tube. Therefore, left tube Salpingectomy and dilation plus curettage were performed.  Heterotopic pregnancy was confirmed by histopathologic evaluation.

Discussion & Conclusions: Heterotopic pregnancy could occur in natural cycle. In regard to metformin as a risk factor of occurrence of heterotopic pregnancy, more studies are needed.