Second-trimester heterotopic pregnancy after in vitro fertilization and embryo transfer--a case report and review of the literature.

Seven cases of heterotopic pregnancies following in vitro fertilization (IVF) and embryo transfer (ET) have been seen. In these cases, concomitant intrauterine and extrauterine pregnancies were described in the first trimester. We present the first case of second-trimester heterotopic pregnancy after IVF with successful surgical treatment of the ectopic pregnancy and subsequent full-term birth of the intrauterine pregnancy. The etiologic factors, possible explanation for the relatively frequent occurrence of heterotopic pregnancies in IVF, and the diagnostic difficulties are presented.