Family doctor

Ectopic Pregnancy

What is an ectopic pregnancy?

An ectopic pregnancy is one that occurs in an abnormal place(outside the uterus). Ectopic pregnancies can occur in many parts of the reproductive system, but more than 95% of all ectopic pregnancies occur in the fallopian tubes. Other sites include the ovaries, the abdominal cavity, the junction of the fallopian tube and uterus, and the cervix.

How and why does it happen?

Normally, once fertilised, the ovum (egg) moves down the fallopian tube towards the uterus (womb), growing in size and complexity to form the blastocyst (from which the embryo and placenta will develop). Within days of conception, the blastocyst attaches itself to the lining of the upper part of the uterus(womb). However, if the passage of the fertilised ovum along the fallopian tube is delayed, then the blastocyst is 'ready' for attachment before it has reached the uterine cavity; this will lead to a tubal pregnancy. Anything that affects the passage of the blastocyst along the fallopian tube may thus increase the likelihood of an ectopic pregnancy.

There are a number of risk factors for ectopic pregnancy, most of which relate to damaged or altered fallopian tubes. Table I categorises these factors according to magnitude of risk, and for each category lists them in decreasing order of risk. Note that for women who have had a tubal ligation or those who are using an intrauterine contraceptive device (IUD), the chance of any pregnancy is very slight; however, if they do become pregnant, then there is a considerable likelihood that that pregnancy will be ectopic.

Note also that the use of fertility treatments such as IVF (in vitro fertilisation) is associated with an increased risk of ectopic pregnancy; furthermore, if it does occur, it is more likely to involve sites apart from the fallopian tubes than an ectopic pregnancy that occurs after natural conception.

Table I: Factors associated with ectopic pregnancy

How do I know if I have an ectopic pregnancy?

An ectopic pregnancy usually causes symptoms early in the pregnancy, either because it begins to fail, or distends the site of implantation. (Rarely, an ectopic pregnancy may continue to develop like a normal one, e.g. within the abdominal cavity, where the growing foetus can be accommodated.) The symptoms are therefore identical to those of a miscarriage occurring in the first trimester (first 13 weeks of pregnancy), i.e. vaginal bleeding and abdominal pain. The most common symptoms are the combination of a missed period and abdominal pain. The pain may vary from mild to severe, and the bleeding may range from scanty to heavy, with clots and/or 'tissue'.It is important to note that sometimes pain or bleeding may not be present with ectopic pregnancy,thus the absence of these symptoms does not altogether exclude it.

Other symptoms reported by women with ectopic pregnancy include those related to pregnancy in general (e.g. breast tenderness, nausea), dizziness or faintness, and shoulder tip pain. The last two symptoms (dizziness/faintness and shoulder tip pain) are particularly important as they suggest significant internal bleeding.

If you are know you are pregnant, and experience abdominal pain or vaginal bleeding, you should notify your doctor immediately. Furthermore, any sexually active woman of childbearing age who develops abdominal pain and/or vaginal bleeding should be given a pregnancy test (even if she has had a tubal ligation or is using an IUD) to rule out ectopic pregnancy or miscarriage. (Pregnancy tests are so accurate nowadays that a pregnant woman is extremely unlikely to have a negative test result.)

How is ectopic pregnancy confirmed?

As noted above, the symptoms of ectopic pregnancy are identical to those of early miscarriage, and unfortunately, the signs (i.e. the doctor's findings on examination) are also usually non-specific. Nevertheless, a woman with suspected ectopic pregnancy or miscarriage should have a careful examination of her abdomen and pelvis (including an internal examination). The doctor may note abdominal tenderness, cervical irritation (pain when the doctor touches the cervix), fever, and rapid heart rate and/or low blood pressure (indicating significant blood loss). Occasionally the doctor feels a mass to one side of the cervix during the internal examination; this mass is the ectopic pregnancy itself. Unfortunately, this 'adnexal mass' is an unreliable sign: doctors may miss them and sometimes feel them on the opposite side to the ectopic pregnancy!

If there is evidence that an ectopic pregnancy has ruptured (e.g. major internal bleeding), the woman is referred for immediate surgery: either laparoscopy (a telescopic examination of the abdomen and pelvic cavity) or laparotomy (surgery to open the abdominal cavity). In most cases however, the symptoms and signs of ectopic pregnancy do not confirm its diagnosis, and further studies are required. In the USA various diagnostic 'plans' have been proposed in order to identify ectopic pregnancy as early as possible, but many of the tests used are only available at the large academic hospitals where the 'plans' were devised. At other sites, an ultrasound of the abdomen and pelvis is usually performed first, using an abdominal scanner or an intravaginal one. So-called 'transvaginal' ultrasound is preferred in many centres, because it can detect pregnancies earlier than a 'transabdominal' one.

The ultrasound may reveal a pregnancy developing normally in the uterus or an obvious ectopic pregnancy. (Evidence of a pregnancy includes a 'gestational sac' with an obvious 'foetal pole' or even a foetal heartbeat.) Unfortunately, the ultrasound results are often unhelpful, with neither a normal nor ectopic pregnancy being seen. Instead, the uterus may appear normal (because the pregnancy is too early to be seen) or show vague abnormalities. In such cases, more tests are required. At this point, many women will be referred for a laparoscopy, to both confirm the diagnosis (and if ectopic pregnancy is found) to treat it. In many hospitals in the USA, however, women with suspected ectopic pregnancy who are not thought to be in imminent danger instead have repeated blood tests (to measure levels of the pregnancy hormone ß-hCG) and repeated ultrasound examinations over the next few days. Some doctors diagnose ectopic pregnancy on the basis of an ultrasound finding of an 'empty uterus' when the ß-hCG level is above that at which it is known that normal pregnancies are always seen, but others rely on further tests in such cases, e.g. a 'diagnostic curettage'. This is basically a 'D&C' followed by examination of the 'curettings' to check if there is any evidence of placental tissue. Presence of placental tissue indicates that the pregnancy was a failing intrauterine one (failing, because a normal pregnancy was not seen on ultrasound); absence of placental tissue indicates that the pregnancy must exist outside the uterus, and further treatment is necessary.

How is ectopic pregnancy treated?

In the past, most women with an ectopic pregnancy died, usually as a result of massive haemorrhage when it ruptured. Fortunately this happens very rarely nowadays, as an ectopic pregnancy is usually diagnosed and treated before rupture occurs. Because of the risk of rupture, the condition is usually treated by termination of the pregnancy, although some stable patients in whom ß-hCG levels are declining may merely be treated 'expectantly' &emdash; i.e. they are closely observed.

There are two primary methods of ending an ectopic pregnancy: either by surgery or the use of the drug methotrexate. Surgery is most commonly performed by laparoscopy, and if possible, involves removal of the ectopic pregnancy from its implantation site, with preservation of the surrounding tissue. Thus, for tubal pregnancies, a 'salpingostomy' is carried out, whereby a slit is made in the fallopian tube over the bulging ectopic pregnancy, and the pregnancy is removed. The tube is then allowed to heal, and is thus preserved. However, if the tube is sufficiently damaged (from rupture of the ectopic pregnancy), then it is usually removed outright (a 'salpingectomy').

In the 1990s, medical treatment with methotrexate has been used increasingly to treat unruptured ectopic pregnancies below a certain size, with the aim of preserving the fallopian tube. Methotrexate targets rapidly dividing cells in the body, and is usually used to treat certain forms of cancer and conditions such as rheumatoid arthritis. It is used in ectopic pregnancy, because the cells of the developing foetus and placenta are rapidly dividing. Methotrexate is usually given by an intramuscular injection, either as a large single dose, or as smaller daily doses given over a few days. The blood levels of ß-hCG must then be closely followed, to check that they decline &emdash; a sign that the ectopic pregnancy is terminating.

Methotrexate is associated with certain side-effects, the most common of which are colicky abdominal pain, and increased pelvic pain (which may be mistaken for rupture). Other effects include nausea, diarrhoea, oral irritation, hair loss, and liver upsets. However, these do not occur as commonly as happens when the drug is used long-term (e.g. for rheumatoid arthritis).

What are the risks of surgery and methotrexate?

The most important short-term risks of salpingostomy and methotrexate are two-fold: that the ectopic pregnancy persists and that it ruptures. Persistent ectopic pregnancy is indicated by ß-hCG levels that do not decrease; it requires further treatment (e.g. use of methotrexate after salpingostomy, or a further dose of methotrexate if that was the primary treatment). Ruptured ectopic pregnancy should be suspected when there is increased abdominal pain or further bleeding, and requires surgical intervention.

Will I still be able to get pregnant in future after an ectopic pregnancy?

There have been many long-term studies that have looked at the reproductive outcomes after the various forms of treatment. After salpingectomy, 49% of those who wished to become pregnant had a subsequent normal pregnancy; after salpingostomy and methotrexate, the figure is closer to 60%.

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