In an ectopic pregnancy, the fertilized egg implants in a location outside the uterus and tries to develop there. The word "ectopic" means "in an abnormal place or position." The most common site is the fallopian tube, the tube that normally carries eggs from the ovary to the uterus. However, ectopic pregnancy can also occur in the ovary, the abdomen, and the cervical canal (the opening from the uterus to the vaginal canal). The phrases "tubal pregnancy," "ovarian pregnancy," "cervical pregnancy," and "abdominal pregnancy" refer to the specific area of an ectopic pregnancy. More than 95% percent of all ectopic pregnancies occur in the fallopian tube. Only 1.5% develop in the abdomen; less than 1% develop in the ovary or the cervix.

Ectopic pregnancy was first described in the eleventh century and was often a fatal condition until the advent of surgery and blood transfusions in the early twentieth...