Ectopic pregnancy

To understand an ectopic pregnancy, then it is important to understand how a normal pregnancy progresses. In a normal pregnancy the egg leaves the ovary and travels down the fallopian tube, where it is met by the male sperm. One of these sperm breaks through the membrane of the egg, and they fuse together, known as fertilisation. The fertilised egg then begins to divide into 2 cells, then 4, 8, 16 etc and continues down the fallopian tube until it reaches the uterus. It then embeds into the uterus wall. The cluster of cells forms a placenta, and a sac which forms around the embryo which also begins to grow from the fertilised egg.

In an ectopic pregnancy the egg is fertilised in the same way, however it does not continue to travel down the fallopian tube. The fertilised egg embeds into the fallopian wall and continues to grow there. In some cases the fertilised egg embeds into another cavity, ovary, cervix or other organ that is outside the uterus but this is rare. The uterus is designed to grow and stretch as the embryo grows, however, the fallopian tube is not designed in this way, and therefore an ectopic pregnancy does not usually survive, and often an embryo does not start to grow. In many cases the body will naturally abort the pregnancy and cause a miscarriage.

There are some groups of women that are at higher risk of an ectopic pregnancy these are women that have suffered: