Occasionally, the developing zygote will implant somewhere other than the uterus; this is called ectopic pregnancy. The most common location for ectopic pregnancies is in a fallopian tube, but they can arise in any tissue that the fertilized zygote can reach (essentially anywhere within the abdomen). Since only the uterus is suited to the development of the embryo, ectopic pregnancy usually results in complications when the developing embryo grows too big for the blood supply of the ectopic location to sustain it any more. When this happens, the ectopic pregnancy is at risk of rupture, potentially resulting in serious blood loss. An ectopic pregnancy can thus be a life-threatening condition.

What Causes Ectopic Pregnancy?

High Estrogen and Progesterone Levels
High levels of estrogen and progesterone increase the risk of ectopic pregnancy because these hormones slow the movement of the fertilized egg through the Fallopian tube. The use of progesterone-secreting intrauterine devices (IUDs), the morning-after pill, and other hormonal methods of contraception often result in high estrogen and progesterone concentration and a subsequent increase in the risk of ectopic pregnancy.

Pelvic Inflammatory Disease
Women with Pelvic Inflammatory Disease (PID) have a high occurrence of ectopic pregnancy. This results from the build-up of scar tissue in the Fallopian tubes, causing damage to cilia and possible tube occlusion.

Tubal Surgery
Tubal ligation is also likely to cause cilia damage. Because ectopic pregnancy is treated with tubal surgery, a history of ectopic pregnancy increases the risk of future occurrences.

Treatment

Early treatment of an ectopic pregnancy with the drug Methotrexate has proven to be a viable alternative to surgical treatment. If administered early in the pregnancy, Methotrexate can disrupt the growth of the developing embryo causing the cessation of pregnancy.

If hemorrhaging has already occurred, surgical laparotomy is necessary to halt blood loss and reduce the risk of shock. Laparotomy often includes repair of the affected Fallopian tube and removal of the developing embryo.