An ectopic pregnancy (EP) occurs when a fertilised egg grows outside the uterus and unfortunately this occurs once in approximately every 70 pregnancies. The great majority of these are in the Fallopian tube but on rare occasions they can occur in other sites such as the junction between the tube and the uterus – this is called an interstitial (or cornual) ectopic pregnancy – the ovary, cervix or in the abdomen itself.
An ectopic pregnancy in the left Fallopian tube
A cornual ectopic pregnancy in the right side of the uterus
Risk factors for EP include previous pelvic infection, pregnancies conceived with IVF or after a reversal of sterilization. Symptoms include irregular vaginal bleeding, ‘stabbing’ lower abdominal pain, fainting and occasionally shoulder discomfort. However, EP’s are also sometimes diagnosed during a routine ultrasound even when no abnormal symptoms having been experienced at all.
Although an EP may be diagnosed by a pelvic ultrasound scan alone, it is common to also take a blood sample to check the level of a pregnancy hormone called beta-human chorionic gonadotrophin (HCG). These two results are then interpreted together to help decide where the pregnancy is. However, it is often necessary to repeat these tests 2 – 7 days later to be certain of the diagnosis.
An EP may be managed in several ways depending on the particular circumstances at the time. Broadly there are three possibilities: watch and wait, surgery and drug therapy.
Watching and waiting may be suitable if the EP is small and the levels of HCG are low and falling quickly. This may suggest that your body is dealing with the EP itself. However this is the least common form of management.
Surgery is frequently the best option and if so, is almost always performed using a laparoscopic or ‘key hole’ approach. Most often the Fallopian tube containing the EP is removed but sometimes it is possible to remove the EP alone and preserve the tube.
Where appropriate, it is possible to try and avoid surgery by giving an intramuscular injection of a drug called methotrexate (MXT). This is a safe option for some women and is successful in approximately 90% of cases where it is used. However, treatment can take several weeks to complete and during this time blood tests are needed to assess progress. There can be side effects of MXT, a second injection may be needed and if the treatment does not work then surgery is likely the only remaining option. Women are advised to wait 3 months from when they receive this treatment before attempting to fall pregnant again.
Although the chance of woman having an EP at all is low, if she does then the chance of another EP in a subsequent pregnancy is around 10% (1 in 10). Because of this it is advisable to have a trans-vaginal ultrasound around 6 weeks after the onset of menstruation to determine where the pregnancy is growing.