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
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.
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
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.