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An ectopic pregnancy occurs when the products of conception implant outside the endometrial cavity (1). The most common site is the fallopian tube - 17.4% in the fimbria, 55% in the ampulla, 25% in the isthmus and 2% in the interstitial portion. Less commonly, a pregnancy implants in the ovary (0.5%), in cervix, scar from a cesarean section or the abdominal cavity (0.1%) (1).
It is estimated that there are around 10,700 ectopic pregnancies in the UK each year, with an incidence of 11.1 in every 1000 pregnancies (2).
It is usually associated with a period of amenorrhoea followed by bleeding and pain. A heterotrophic pregnancy is when an intrauterine and an extrauterine pregnancy occur together in a woman (3).
Note though that the advice from the CEMD report (1) states "it is
essential that GPs and other clinicians, including staff in A and E departments,
consider the diagnosis of ectopic pregnancy in any woman of reproductive age
who complains of abdominal pain. It is important to recognise that the clinical
presentation is not often "classical". BhCG (pregnancy) testing should
be considered in any woman of reproductive age with unexplained abdominal pain
whether or not she has missed a period or had abnormal vaginal bleeding."
Some women (around 8 to 31%) with suspected ectopic pregnancies may present without any signs of an extra- or intra-uterine pregnancy on initial transvaginal ultrasound scan (TVS). These women are categorized as having a pregnancy of unknown location (PUL).
- around 25-50% of women with an ectopic pregnancy initially presents as PUL
- approximately 7 to 20% of women with a PUL will eventually be given a diagnosis of an ectopic pregnancy (1)
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