Ectopic pregnancy

An ectopic pregnancy is a pregnancy where the fertilized egg implants somewhere other than the uterus. Pregnancies of this type are generally not viable and are dangerous to the mother. About 1% of pregnancies are ectopic and in 98% of those cases, the egg implants in the fallopian tube. In rarer cases, the egg may implant in an ovary, the cervix, or elsewhere in the abdomen. Many ectopic pregnancies occur in perfectly healthy women, but some conditions are risk factors, such as pelvic inflammatory disease, infertility, smoking, sterilzation by tubal ligation and the use of an IUD.
In a typical ectopic pregnancy, the egg's attachment to the fallopian tube invades blood vessels and will cause bleeding. However, in about half of cases, the egg will eventually spontaneously abort and the damage will repair itself. In the other cases the bleeding can become life threatening as the egg grows within the tube.
The symptoms of an ectopic pregnancy can be mild or even completely absent. However, in serious cases, the patient can suffer increasing bleeding and pain.
Although ectopic pregnancies were a common cause of maternal death in the past, and still are in developing countries, they rarely lead to death in the United States and other developed countries. A physician will generally suspect an ectopic pregnancy in any pregnant patient with abdominal pain. Ultrasound has made it much easier to diagnose ectopic pregnancy. A laparotomy is often performed to confirm.
For the past twenty years, methotrexate is the treatment of choice as it will usually induce an abortion. However, in serious cases, surgery may be necessary.
Ectopic pregnancy at NIH
Ectopic pregnancy at Wikipedia
Ectopic pregnancy at Mayo Clinic