In a normal pregnancy the egg (ovum) is fertilised by the sperm in the fallopian tube and travels down to the uterus (womb) for implantation. An ectopic pregnancy, also called a tubal pregnancy, occurs when the fertilised egg is implanted outside the uterus. The most common site for implantation outside the uterus is the fallopian tube but, in rare cases, implantation can also occur in the ovary and cervix. As the fallopian tube cannot accommodate the growing foetus, the tube may expand and eventually rupture.
A pregnancy that occurs outside the uterus cannot continue.
Why do ectopic pregnancies occur?
Sometimes no obvious reason is found for an ectopic pregnancy. However, some of the most common factors associated with ectopic pregnancy are:
- Pelvic inflammatory disease (PID). This is caused by infection with a sexually transmitted disease such as chlamydia or gonorrhoea. These infections can lead to scarring and blockage in the fallopian tubes, making it difficult for the fertilised egg to travel down the damaged tube for implantation in the uterus.
- Previous ectopic pregnancy. There is a 10% chance of having another ectopic pregnancy.
- Previous surgery to a fallopian tube, which may lead to adhesions and scarring.
- Endometriosis. This is where normal uterine tissue is found outside the uterus. It can lead to blockage or obstruction of the fallopian tubes.
- Intrauterine devices. These are contraceptive devices designed to prevent implantation. Because they can increase the risk of PID, some theories conclude that they also increase the risk of ectopic pregnancy.
What are the symptoms of an ectopic pregnancy?
Symptoms associated with an ectopic pregnancy include:
- Lower abdominal pain. This may be sudden and severe in onset or mild and intermittent. Pain may also be felt in the shoulder tip, especially if there is internal bleeding irritating the diaphragm.
- Vaginal bleeding. This may be slight, brownish in colour and continuous. In women who do not yet know they are pregnant, it may be taken as a missed period.
- Fainting/collapse/feeling of weakness/dizziness.
These symptoms can occur very early in pregnancy, even before the woman suspects that she is pregnant. Some women experience sudden and severe symptoms; others experience a more gradual onset. If you are concerned at all, you should consult your GP or obstetrician.
What kind of tests will I need to have? If your doctor suspects an ectopic pregnancy, he will take a full medical history and examine you for typical signs.
A blood test will be taken to test for the pregnancy hormone Human Chorionic Gonadotroph (HCG). The levels of HCG detected for a normal pregnancy will differ from the levels detected for an ectopic pregnancy. In a normal pregnancy HCG doubles in the first 10 days, this does not happen in an ectopic pregnancy.
A pelvic examination may be performed in hospital.
You will be monitored for pallor; a weak, fast pulse and falling blood pressure as these symptoms may indicate internal bleeding.
A non-invasive test called a pelvic ultrasound will show an empty uterus and a foetus in the fallopian tube. In a normal pregnancy the uterus would show the foetus in the uterus.
Sometimes there may be doubt about the diagnosis of ectopic pregnancy as although a pregnancy test will return a positive result, it may be too early for the ultrasound to show exactly where the foetus is. In these cases a laparoscopy may be performed to confirm the diagnosis. This involves inserting a camera into the abdomen through a small incision.
Will I need surgery?
An ectopic pregnancy is a medical emergency. A woman with an ectopic pregnancy who presents with low blood pressure and shock will need intravenous fluids and perhaps a blood transfusion. Pain relief will also be given.
A laparoscopy or laparotomy will be performed to look at the fallopian tubes.
Both procedures are done under general anaesthetic. The damaged fallopian tube is opened and the pregnancy removed (salpingotomy) or the damaged tube is taken out altogether (salpingectomy).
Sometimes the fallopian tube doesn't rupture and the pregnancy is slowly absorbed over time. In these small number of cases no surgery is needed.