Pregnancy begins with a fertilized egg. Normally, the fertilized egg attaches to the lining of the uterus. An ectopic pregnancy occurs when a fertilized egg implants and grows outside the main cavity of the uterus.
An ectopic pregnancy most often occurs in a fallopian tube, which carries eggs from the ovaries to the uterus. This type of ectopic pregnancy is called a tubal pregnancy. Sometimes, an ectopic pregnancy occurs in other areas of the body, such as the ovary, abdominal cavity or the lower part of the uterus (cervix), which connects to the vagina.
An ectopic pregnancy can't proceed normally. The fertilized egg can't survive, and the growing tissue may cause life-threatening bleeding, if left untreated.

In a healthy pregnancy, the fertilized egg attaches itself to the lining of the uterus. In an ectopic pregnancy, the egg attaches itself somewhere outside the uterus usually to the inside of a fallopian tube.
You may not notice any symptoms at first. However, some women who have an ectopic pregnancy have the usual early signs or symptoms of pregnancy — a missed period, breast tenderness and nausea.
If you take a pregnancy test, the result will be positive. Still, an ectopic pregnancy can't continue as normal.
As the fertilized egg grows in the improper place, signs and symptoms become more noticeable.
Often, the first warning signs of an ectopic pregnancy are light vaginal bleeding and pelvic pain.
If blood leaks from the fallopian tube, you may feel shoulder pain or an urge to have a bowel movement. Your specific symptoms depend on where the blood collects and which nerves are irritated.
If the fertilized egg continues to grow in the fallopian tube, it can cause the tube to rupture. Heavy bleeding inside the abdomen is likely. Symptoms of this life-threatening event include extreme lightheadedness, fainting and shock.
Seek emergency medical help if you have any signs or symptoms of an ectopic pregnancy, including:
A tubal pregnancy — the most common type of ectopic pregnancy — happens when a fertilized egg gets stuck on its way to the uterus, often because the fallopian tube is damaged by inflammation or is misshapen. Hormonal imbalances or abnormal development of the fertilized egg also might play a role.
Some things that make you more likely to have an ectopic pregnancy are:
An ectopic pregnancy can cause your fallopian tube to burst open. Without treatment, the ruptured tube can lead to life-threatening bleeding.
There's no way to prevent an ectopic pregnancy, but here are some ways to decrease your risk: