Ectopic pregnancies occur when the fertilized ovum implants outside of the uterine fundus. About 1 in 150 pregnancies results in ectopic implantation. Most cannot be sustained at extrauterine sites. However, a tubal ectopic pregnancy, as diagrammed here, may proceed for several weeks, but the enlargement can rupture the tube and lead to acute, life-threatening bleeding, often about 6 weeks after a previous menstrual period.
Hematosalpinx: tubal gestation
Ruptured tubal pregnancy with marked hemorrhage (hematosalpinx). The tiny embryo is identifiable in the center of the clot.This is a ruptured tubal ectopic pregnancy. Note the twin fetuses at the lower right adjacent to the blood clot at the left*.
Here is another ectopic pregnancy in a fallopian tube that was excised. This is a medical emergency because of the sudden rupture with hemoperitoneum.
Hematosalpinx with rupture complicating tubal pregnancy
A positive pregnancy test (presence of human chorionic gonadotropin), ultrasound, and culdocentesis with presence of blood are helpful in making the diagnosis of ectopic pregnancy. Note the presence of chorionic villi & hemorrhage within the tubal lumen
Tubal pregnancy