Ectopic pregnancy, also known as a tubal pregnancy, occurs when the pregnancy implants outside of the womb. It can occur in several places, eg. the ovary, the abdomen, the cervix, at the join between the tube and the womb (cornua), but the most common place is within the fallopian tube. Pregnancy can even occur in both the womb and the tube at the same time (heterotopic pregnancy), but this is rare, occuring in only about 1/10,000 pregnancies.
How Common is It?
In the UK, ectopics happen in about 0.25-1% of all pregnancies. It is, however, getting more common. In Finland, the number of ectopics has tripled between 1966 and 1985 and in the US there was a four-fold rise between 1970 and 1983. In Jamaica there is an unusually high rate of ectopic pregnancy (1 in 28 deliveries).
What Causes the Ectopic Pregnancy?
Many factors are known to increase the risk of having an ectopic pregnancy. Anything that alters the tubal function may affect further pregnancies. Fallopian tubes aren\'t like a hollow pipe that sits there with the egg rolling down. They have little hairs on the inside (cilia) which move with a wave-like motion to encourage the egg toward the womb. If the tube becomes blocked or the cilia damaged then ectopic is more likely.
Often none of the risk factors below are present and there is no obvious reason - it was just bad luck.
- Advancing age
- Pelvic inflammatory disease - eg. previous chlamydia or gonorrhoea. Infection causes scar tissue adhesions in the tube and may damage the cilia. PID is one of the main causes of the increase seen in ectopic pregnancies in recent years. Risk of an ectopic pregnancy increases about 7-fold after a woman suffers acute pelvic infection.
- Tubal surgery - women who have had operations on their tubes are more at risk of ectopic. This includes tubal ligatoin, reversal of sterilisation or tubal surgery for a previous ectopic.
- Previous ectopic - about 10-20% of those attempting pregnancy after one ectopic will have another.
- DES exposure - this is a drug that was once used during pregnancy, until it was found that female babies of women who used it were at risk of developmental abnormalities of the genital system. Their tubes are more likely to be abnormal and predisposed to ectopic pregnancy. This is a very rare problem and you would most likely already know about it.
- Previous termination of pregnancy - the risk of ectopic increases among those who have had two or more terminations, particularly if there was infection afterwards.
- IVF (test-tube baby) and ovulation induction - both these techniques of assisted reproduction are associated with increased chances of ectopic pregnancy.