By now, you’re well versed in the reproductive process: The egg is fertilized in a fallopian tube and the resulting embryo attaches to the uterine wall, where it grows into a fetus. But in about 2 to 10 percent of cases, something goes awry and the egg implants outside the uterus. This is called an ectopic pregnancy. The vast majority of the time, it occurs inside one of the fallopian tubes, but the embryo can also take root in an ovary, the cervix, or the abdominal cavity.

Ectopic pregnancies are usually caused by a condition that slows or blocks the embryo’s journey down the fallopian tube, giving it time to implant on the wall. Nearly half of cases are attributed to inflammation of the tubes, called salpingitis, or pelvic inflammatory disease, an inflammation of the uterus, fallopian tubes, or ovaries. Endometriosis (a condition in which uterine tissue grows outside the uterus), the sexually transmitted infections gonorrhea and chlamydia, and supplemental estrogen and progesterone (from fertility treatments, birth control pills, or the morning-after pill) are also potential causes.

For the first few weeks, a woman may believe that she has a normal pregnancy— she’ll develop the same missed periods, nausea, and fatigue. But other symptoms of an ectopic pregnancy include vaginal bleeding, pain in the lower abdomen, and cramping on one side of the pelvis. Since an embryo can’t grow and develop normally in a fallopian tube, about half of these pregnancies end naturally, sometimes with the rupture of the tube, which is a medical emergency. Today, most ectopic pregnancies are diagnosed early by sonograms, well before they rupture. They can be treated with the drug methotrexate or by laparoscopic surgery to destroy or remove the embryo.

ADDITIONAL FACTS

  1. In some cases, a woman can become pregnant after having her tubes tied. If the procedure fails and she becomes pregnant, chances are it will be an ectopic pregnancy.
  2. If a woman has previously had an ectopic pregnancy, the risk that she’ll have another is higher.
  3. Ectopic pregnancies are known as tubal pregnancies, because more than 90 percent occur in the fallopian tubes.
  4. In Greek, the word ectopic means “out of place.”