Causes of Vaginal Bleeding During an Ectopic Pregnancy

One of 60 pregnancies is ectopic, or growing outside of the uterus. Vaginal bleeding is common in early pregnancy, occurring in 20 percent to 30 percent of all pregnancies, the American Pregnancy Association says. Vaginal bleeding in ectopic pregnancy can be heavier than bleeding seen in intrauterine pregnancies. Bleeding in ectopic pregnancy occurs from two sites: the uterine lining and the site of rupture.

Implantation Spotting

Most ectopic pregnancies implant in the Fallopian tube, the tube the embryo travels through to reach the uterus. Bleeding may occur when the embryo first implants in the tube, just as it often does when an embryo first implants in the uterus. This type of bleeding may appear as if it's coming from embryo implantation in the uterus because there's no way to distinguish it from uterine bleeding without an ultrasound, which shows no embryo in the uterus. If an ultrasound shows the pregnancy is ectopic before rupture occurs, methotrexate, a chemotherapy drug, can be taken orally to stop the growth of the embryo.

Low Progesterone Levels

Ectopic pregnancies generally produce less progesterone (a pregnancy hormone) than uterine pregnancies, because the embryo isn't able to implant as well outside the uterus. Because progesterone keeps the growing uterine lining intact and falling levels are responsible for initiating menstrual bleeding, lower than normal levels of progesterone lead to the breakdown of the built-up uterine lining. The bleeding is similar to what would occur in a very early miscarriage and comes from the uterus. A woman may think she's having a late heavy period or an early miscarriage.

Rupture

When the Fallopian tube distends as far as it can, it begins to rupture, which can cause severe bleeding. Blood may accumulate in the abdominal cavity; shock from severe blood loss may occur. Symptoms of shock include falling blood pressure, lightheadness and a feeling of impending doom. Shock is a medical emergency and needs immediate attention. Surgical removal of the tube is usually necessary to save the life of the mother. About 2 percent implant in another site outside the uterus, with the ovary and cervix the two most common. Neither the cervix nor the ovary is large enough for a pregnancy to grow more than a few weeks before rupture and bleeding from the ovary or cervix occurs. Symptoms of rupture are the same as those in Fallopian tube rupture.