A pregnancy that develops outside the uterus, usually in a fallopian tube
- Age, genetics, and lifestyle are not significant factors
About 1 in 100 pregnancies is ectopic. In an ectopic pregnancy, a fertilized egg becomes implanted in tissues outside the uterus instead of in the uterine lining. The egg then begins to develop into an embryo. In most ectopic pregnancies, the fertilized egg lodges inside one of the two fallopian tubes. Rarely, the egg implants in the cervix, in one of the ovaries, or in the abdominal cavity. The embryo is not able to grow normally in an ectopic pregnancy and only rarely survives.
If the placenta develops inside a fallopian tube and the embryo grows, the fallopian tube will eventually rupture, causing life-threatening bleeding into the mother’s abdominal cavity. Ectopic pregnancies need to be removed surgically as soon as possible after detection because of the risk to the mother.
What are the causes?
Ectopic pregnancy may occur as a result of previous damage to one of the fallopian tubes, which may obstruct the passage of a fertilized egg along the tube to the uterus. The egg then implants in the wall of the tube instead of in the uterus. This prior damage may have been caused by an unsuccessful or a reversed sterilization procedure (see Female sterilization) or a fallopian tube infection (see Pelvic inflammatory disease).
What are the symptoms?
An ectopic pregnancy usually produces symptoms in the first 6–7 weeks, sometimes even before the woman realizes she is pregnant. However, most women who have an ectopic pregnancy will have missed a menstrual period by the time symptoms appear. The symptoms may include:
Pain that is low down on one side of the abdomen.
Irregular vaginal bleeding that may be confused with menstruation.
If the ectopic pregnancy is not detected and a fallopian tube ruptures, further symptoms may develop that include:
Sudden, severe pain that gradually spreads throughout the abdomen.
Shoulder pain (referred pain due to irritation of the diaphragm).
Sudden internal bleeding follows the rupture of the fallopian tube and may cause shock. If you are in shock, you may sweat profusely and feel faint. It is important to see your doctor at once if you have abdominal pain or vaginal bleeding and might be pregnant. If you experience severe pain or shock, call an ambulance immediately.
What might be done?
If you are not sure whether or not you are pregnant, a pregnancy test will be performed. If the test is positive, your doctor may arrange for you to have an ultrasound scan to find out the position of the embryo. You may also have a blood test to measure blood levels of human chorionic gonadotropin (HCG), a hormone that is produced in lower amounts than normal in ectopic pregnancies. To confirm the diagnosis, an examination of the inside of the abdominal cavity may be performed under general anaesthesia (see Laparoscopy).
If an ectopic pregnancy is confirmed, the embryo and surrounding tissue are usually removed. This may be done by laparoscopy or by conventional surgery. A damaged fallopian tube will be repaired if possible, but, if it is badly damaged, the tube may be removed to prevent another ectopic pregnancy from occurring at the same site. If an ectopic pregnancy is diagnosed early, it may be treated with the drug metho-trexate rather than by surgery.
What is the prognosis?
Although approximately 1 in 10 women will have a further ectopic pregnancy, most affected women can have normal pregnancies even if one fallopian tube has been removed. If both tubes have been damaged, in-vitro fertilization (see Assisted conception) may help a woman to become pregnant.
In subsequent pregnancies, an ultrasound scan (see Ultrasound scanning in pregnancy) may be carried out at an early stage to check that the fetus is developing in the uterus.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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