What Is Ectopic Pregnancy? Symptoms, Causes, Diagnosis, Treatment, and Prevention

An ectopic pregnancy occurs when a fertilized egg implants somewhere other than a woman's uterus. In a normal pregnancy, when sperm fertilizes an egg, the resulting zygote moves through the fallopian tube and eventually implants in the lining of the uterus. With an ectopic pregnancy, a fertilized egg grows outside the uterus. The vast majority of ectopic pregnancies — more than 90 percent — occur in a fallopian tube.

When this happens, as the pregnancy progresses, it can cause the fallopian tube to rupture, which can cause life-threatening internal bleeding in the woman. (1) In other, rare instances, an ectopic pregnancy can be found in the ovary, cervix, or somewhere else in the abdomen. (2)

Regardless of where outside the uterus the zygote implants, an ectopic pregnancy is not a viable pregnancy: It cannot result in a healthy baby, and it needs to be ended to protect the health of the pregnant woman. That’s why they require prompt diagnosis and treatment. (3)

Anything that blocks or impedes the safe passage of a fertilized egg through the fallopian tube (such as scarring) increases the risk that the egg will implant in the fallopian tube. So a person may be more likely to have an ectopic pregnancy in the case of:

• A previous ectopic pregnancy
• Prior surgery in the pelvis or abdomen
• A sexually transmitted infection or STD (sexually transmitted disease)
• Pelvic inflammatory disease (PID)
• Endometriosis, a condition where tissue that’s similar to the lining of the uterus grows outside the uterus in the pelvic cavity
• The pregnancy occurred with an IUD (intrauterine device) in place
• A history of cigarette smoking
• Older age (older than 35)
• Past use of assisted reproductive technology, such as in vitro fertilization (1,2)

But the reality is: About 50 percent of women who have an ectopic pregnancy don’t have known risk factors. (1)

If your doctor suspects you have an ectopic pregnancy, he or she will use a combination of blood tests and ultrasound scans to make a diagnosis. You’ll likely have a pregnancy test that measures how much human chorionic gonadotropin (hCG) is in your blood; in an ectopic pregnancy, the blood level of hCG is usually lower than in a normally developing pregnancy, and it rises at a slower-than-normal rate after implantation. That’s why hCG is usually measured more than once. (2) Meanwhile, an ultrasound scan of the lower abdomen can locate the implanted embryo and determine whether it is inside or outside the uterus. (2)

Prognosis for Ectopic Pregnancy

Because an ectopic pregnancy cannot move naturally or be moved to the uterus, it always requires treatment to end the pregnancy. (1) Otherwise, it could be life-threatening to the pregnant woman.

In any case, ectopic pregnancies are not viable pregnancies: They cannot result in a healthy baby, and they need to be ended early to protect the health of the pregnant woman. That’s why they require prompt diagnosis and treatment. (3)

The good news: Many women who have had an ectopic pregnancy are able to have normal, healthy pregnancies later on. That said, women who have had an ectopic pregnancy should seek early evaluation of a later pregnancy by a healthcare provider. (2) If a woman does have trouble getting pregnant after an ectopic pregnancy, it may be due to problems in the fallopian tubes or scarring in the pelvis; in these instances, fertility testing and treatment can improve the chances of success. (2)

There is no way to prevent an ectopic pregnancy, but you can lower your risk by using condoms when you have sex (before you try to conceive) to help prevent sexually transmitted infections and reduce the risk of pelvic inflammatory disease. You can also stop smoking, if you smoke. (5) Smoking cigarettes is a known risk factor for ectopic pregnancy.

Approximately 1 in 50 — or 2 percent of — pregnancies in the United States is ectopic. (6) If you’ve had one ectopic pregnancy, you have a 15 percent chance of having another. (6)

As described in the section on causes and risk factors, anything that could block or impede passage of an egg through the fallopian tube (such as scarring) increases the risk that an egg will implant in the tube. Women who have a history of the following conditions may be more likely to have ectopic pregnancy:

• Previous ectopic pregnancy
• Surgery in her pelvis or abdomen
• Sexually transmitted infection, pelvic inflammatory disease (PID), endometriosis
• Became pregnant with an IUD in place
• Used assisted reproductive technology, such as in vitro fertilization, in the past (1,2)

Women who have had one ectopic pregnancy face a 15 percent chance of having another ectopic pregnancy. (6) Many women who have had an ectopic pregnancy are able to have healthy pregnancies later on. (2)

To learn more about ectopic pregnancy, check out the following websites.

American College of Obstetricians and Gynecologists (ACOG)

ACOG is a go-to source for research-supported information about women’s reproductive health issues, including fertility, conception, pregnancy, and best practices for each of these issues.

American Society for Reproductive Medicine

A first-rate resource on women’s reproductive health issues, the organization provides patient education materials on myriad issues, such as pregnancy challenges, fertility treatments, and more.

Planned Parenthood

A reliable source of information about reproductive and sexual health and healthcare, Planned Parenthood provides vital facts about women’s health and wellness, sexually transmitted infections, birth control, pregnancy, and more.