An ectopic pregnancy is one that occurs at any site other than the endometrium. The majority of ectopic pregnancies occur in the fallopian tubes, but they may occur even within the peritoneal cavity.
Ectopic pregnancy is a major cause of maternal morbidity and mortality, the incidence of which is increasing. In the UK there is an incidence of 11.5 per 1,000 pregnancies.
Some women with ectopic pregnancy have no demonstrable risk factors.
However, in a significant proportion of women risk factors such as previous ectopic pregnancy, a history of infertility, endometriosis, previous fallopian tube surgery and/or salpingitis are present.
A patient with a prior ectopic pregnancy has a 10-25 per cent chance of a future tubal pregnancy. After an episode of acute salpingitis there is a sevenfold increase in the risk of ectopic pregnancy.
The rising incidence of ectopic pregnancies may be attributed in part to an increase in Chlamydia trachomatis infections resulting in pelvic inflammatory disease. The incidence of tubal damage increases after successive episodes of pelvic inflammatory disease (PID); given that more than 50 per cent of women who have PID may be asymptomatic, this is a significant consideration.
Ectopic pregnancy is also associated with increasing maternal age and smoking.
When a progesterone intrauterine contraceptive device is being used, if pregnancy does occur it is more likely to be ectopic.
Following assisted reproduction techniques there is a threefold increase in the rate of ectopic pregnancy and an increased risk of heterotopic pregnancy, where there is an intrauterine pregnancy as well as an ectopic one.
Ectopic pregnancy usually presents with amenorrhoea and then pain and vaginal bleeding. On examination there may be abdominal, as well as adnexal tenderness. Importantly, history and examination may not exclude the possibility of an ectopic pregnancy; up to 9 per cent of women do not report any pain.
There should be a high index of suspicion of ectopic pregnancy if risk factors are present. If ectopic pregnancy is suspected, further investigations must be carried out.
A woman may also present with haemodynamic shock with haemoperitoneum requiring resuscitation. Haemoperitoneum may cause referred shoulder tip pain.
Approximately 20 per cent of patients with ectopic pregnancies are haemodynamically compromised at initial presentation, suggesting rupture.
A hospital referral to an emergency gynaecology or early pregnancy unit may be appropriate.
Ectopic pregnancy can be a life-threatening situation. The common differential diagnoses to consider include appendicitis, salpingitis, ruptured corpus luteum cyst, abortion, ovarian torsion and urinary tract problems.
Investigations include measuring serum concentrations of human chorionic gonadotrophin (hCG) and transvaginal ultrasound examination. The latter can be used to visualise an intrauterine pregnancy 38 days after the last menstrual period. Doppler ultrasound may be helpful when a gestational sac cannot be identified. Usually a visualised intrauterine pregnancy tends to exclude an ectopic one.
Ectopic pregnancies, in addition to non-viable pregnancies, usually give rise to lower concentrations of hCG. The change in concentration is also useful clinically. During the first six to seven weeks of pregnancy, levels double every 48 hours in 90 per cent of intrauterine pregnancies, but this doubling may be normal in 17 per cent of ectopic pregnancies and abnormal in 13 per cent of intrauterine pregnancies.
While surgery is the mainstay of treatment for ectopic pregnancy, expectant and medical management should be considered. If serial measurements of hCG levels are falling, expectant management might be an option because some ectopic pregnancies resolve spontaneously.
If the initial hCG is less than 1,000IU/l, expectant management may be successful in up to 90 per cent of women, provided that there are no clinical symptoms and signs of rupture.
Ectopic pregnancies that are causing minimal symptoms may be safely and successfully managed in 90 per cent of cases with 50mg/m2 intramuscular methotrexate therapy.
Moreover, if conservative tubal surgery has failed and there is evidence of persistent trophoblast, methotrexate treatment is indicated. Interestingly, methotrexate therapy and laparoscopic salpingostomy were shown to be equally effective in a randomised controlled trial.
It is recommended that the adnexal mass is less than 3.5cm on ultrasound and hCG levels of less than 5,000IU/l before initiating methotrexate treatment.
Patients undergoing this treatment would have to comply with follow-up appointments until hCG is nearly undetectable.
Contraindications to methotrexate treatment include acute infection, severe anaemia, renal or liver impairment or active peptic ulcer disease.
Treatment may be accompanied by lower abdominal pain due to degeneration of the trophoblast; side-effects include nausea and stomatitis. Pregnancy must be avoided until at least hCG surveillance is complete.
Alternatively, methotrexate may be injected into the ectopic pregnancy.
However, this is less successful than systemic treatment and needs to be ultrasound-guided.
Salpingectomy and salpingostomy are performed by laparoscopy or laparotomy.
If the fallopian tube is irreparably damaged, salpingectomy is the preferred procedure because of the significant risk of recurrence of ectopic pregnancy.
Laparotomy is only indicated for patients who are haemodynamically unstable. But it may be necessitated if a laparoscopic approach is difficult, for example, if multiple adhesions are present. Following laparoscopy, patients have a faster recovery period.
Laparoscopy and laparotomy have similar complication rates and that there is a higher risk of persistent trophoblast with laparoscopic treatment.
If there is persistent trophoblastic tissue serial measurements of hCG are necessary.
Women with suspected ectopic pregnancy need to be referred to hospital as soon as possible and must be informed of the options available.
For example, the clinical scenario may require a diagnostic laparoscopy and medical management may not be possible.
It is important to consider the psychological well-being of the patient who has to cope with the loss of a pregnancy and a potential reduction in future fertility. Women should be reassured that rates of intrauterine pregnancy after ectopic pregnancy can be up to 90 per cent according to some studies, regardless of whether treatment is expectant, medical or surgical.
Laparoscopic treatment, when compared with laparotomy, has a higher rate of intrauterine pregnancy. Ectopic pregnancy recurrence is more likely in patients with tubal damage and previous spontaneous miscarriage.
Dr Kochhar is SHO and Mr Mascarenhas is consultant obstetrician and gynaecologist, St Thomas' Hospital, London.
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