Ectopic Pregnancy

An ectopic pregnancy is one that occurs anywhere outside the uterus. By far the commonest place for ectopic pregnancy is the fallopian tubes. There are a few documented cases of viable pregnancy outside the uterus and tubes but as a general rule only an intrauterine pregnancy is viable.

Pregnancy within a rudimentary horn of a bicornuate uterus is not actually ectopic in that it is within the corpus uteri but it will present very much like an ectopic pregnancy, although probably a little later.

In the 3 year period 2000 to 2002 there were 30,100 ectopic pregnancies in the UK resulting in 11 maternal deaths. Both this incidence of 11.0 per 1,000 pregnancies, or just over 1% and the death rate has remained static in recent years.¹

The Royal College of Obstetricians and Gynaecologists triennial Confidential Report into Maternal Mortality was started in 1952 but now it is part of the work of NICE.

• Pelvic inflammatory disease may cause complete tubal occlusion or delay the transport of the embryo so that implantation occurs in the tube. Adhesions from infection and inflammation from endometriosis may play a part.
• Ectopic pregnancy has been reported in tubes that have been divided in a sterilisation operation and where they have been reconstructed to reverse one.
• Ectopic pregnancy has been reported in the treatment of infertility.
• Right sided tubal pregnancy is commoner than on the left. This is thought to be from spread of infection from appendicitis.
• The ability of the tube to expand increases from medially to laterally. Hence a more lateral implantation will present later as either pain or rupture.
• Where an IUCD or progestogen-only oral contraceptives, including emergency contraception fails, the risk of a pregnancy being ectopic is greater than with other forms of contraception. Depot and implant contraception may not have the same risks. Ectopic pregnancy has been reported with implant contraception with etonogestrel (Implanon™) but appears rare.²

An IUCD, being a foreign body with threads hanging into the vagina, increases the risk of infection. It is effective at preventing intrauterine pregnancy but probably ineffective at preventing pregnancy at other sites. Therefore, if pregnancy occurs with an IUCD in situ, think of ectopic pregnancy.

History

• The first symptom is usually pain. This may be left or right iliac fossa pain or it may be central and suprapubic. If vaginal bleeding occurs it is much less significant than the pain.
  There may be a missed period and signs of pregnancy, perhaps even a positive pregnancy test. 30% of ectopics present before a period has been missed.
• There may be a history of a previous ectopic pregnancy. After one ectopic pregnancy the chance of another in the other tube is much increased.
• If the ectopic pregnancy has ruptured, bleeding is profuse and there may be features of hypovolaemic shock including feeling dizzy on standing. Most bleeding will be into the pelvis and so vaginal bleeding may be minimal and misleading.

Examination

• There may be some tenderness in the suprapubic region to left or right of the midline.
• If bleeding has started there may be peritonism and signs of an acute abdomen.
• There may be signs of early pregnancy such as fullness and tenderness of the breasts.
• Bimanual vaginal examination may reveal a tender fullness of one adnexum but some authorities recommend that this should not be done as the examination may rupture the tubal pregnancy. There is evidence that vaginal examination in suspected ectopic pregnancy adds nothing to the clinical picture³ and so should be avoided. The cited paper is just one of many reaching a similar conclusion.
• A check must be made for signs of blood loss. If there is hypovolaemic shock, resuscitation and transfer to hospital must occur without delay.

• In threatened abortion, vaginal bleeding is the predominant feature and pain may come later as the cervix dilates. In ectopic pregnancy, pain usually comes first and if vaginal bleeding occurs it is of much less significance.
• The differential diagnosis is also as for left iliac fossa pain or right iliac fossa pain.

• The most accurate method to detect a tubal pregnancy is transvaginal ultrasound.⁴ Its availability improves management.⁵
• Quantitative assessment of hCG levels is of value in confirming pregnancy and follow up if there is medical or conservative management.⁴
• If hCG is below 1000 units and ultrasound has failed to locate an intrauterine or tubal pregnancy it is called a pregnancy of unknown location.⁴

Admit as an emergency if the diagnosis of ectopic pregnancy is considered a possibility. A bedside pregnancy test should be performed on all women of childbearing age presenting with lower abdominal pain where pregnancy is even the remotest possibility.

Expectant management in hospital is an option for a woman who is clinically stable with a diagnosed ectopic pregnancy and hCG level that is below 1000 and falling.⁴ Transvaginal ultrasound examination and measurement of hCG can make laparoscopy unnecessary in some cases. The majority of cases can be managed without surgery⁶ although there is still some uncertainty about the best policy. Sometimes there is a positive pregnancy test but no gestation is found. These are classified as pregnancy of unknown location.

• Medical management is appropriate in selected cases.⁴ A single intramuscular dose of methotrexate is given to kill the fetus.⁷ This is ethically justified as it is not viable and may be a risk to the life and health of the mother. The dose is usually between 50 and 90 mg dependent upon the woman's surface area. Levels of hCG are checked on day 4 and 7 and if they fail to fall at least 15% between days 4 and 7 a second dose is administered. 14% require the 2nd dose. Fewer than 10% require surgical intervention.⁴
• Clear instruction must be given about the need for follow-up and the ability to return to the ward if there are problems. 7% have rupture of the tube during follow-up.
• It can be difficult to distinguish the pain of separation of the trophoblast from tubal rupture. After the methotrexate there may be symptoms of methotrexate toxicity such as stomatitis. Reliable contraception must be used for at least 3 months to prevent conception after methotrexate.
• Medical therapy is used only if the initial hCG levels were below 3000. It can work at levels up to 5000 but quality of life figures suggest that above 3000 units surgical intervention is preferable.

Surgical

• Bleeding can be so profuse that immediate laparotomy is required to stem the flow and it may not be feasible to correct shock fully before operation.
• If the patient is not bleeding profusely, a laparoscopic approach is preferable.⁴ There is no marked difference in outcome between a laparoscopy and laparotomy in terms of future ectopic pregnancy and future successful outcome. The traditional treatment is salpingectomy but salpingotomy may be employed to try to retain the chance of a future successful pregnancy via that tube. If the contralateral tube looks healthy there is no advantage to salpingotomy. The more conservative approach may be more likely to lead to normal pregnancy⁸ but the differences are not very large. If the contralateral tube looks diseased then laparoscopic salpingotomy is the treatment of choice.

This complex situation has been subjected to a Cochrane review.⁹

• Persistent trophoblast occurs in about 4% of cases with salpingectomy and 8% with salpingotomy.⁴ It is associated with delayed haemorrhage. The risk is greater with preoperative hCG levels above 3000, a rapid preoperative rise in hCG and active tubal bleeding. Treatment is to give methotrexate. Some people give it prophylactically at the time of operation.¹⁰
• Methotrexate is the method of treatment preferred by many patients.¹⁰
• If the woman is Rhesus negative, she should receive anti-D.⁴

Cornual pregnancy does not represent pregnancy in a rudimentary horn of a bicornuate uterus but pregnancy in the interstitial rather than extrauterine part of the tube. Cornual pregnancies represent 2 to 4% of ectopic pregnancy and it has a mortality of 2 to 2.5%.¹¹ This compares with 11 deaths in 30,100 other ectopics,¹ or a rate of about 1 in 3,000. It can be diagnosed by ultrasound in only 70% of cases. It tends to present early and suddenly and often there is catastrophic haemorrhage before diagnosis is made. The CEMACH report¹² makes two important points about the the diagnosis of ectopic pregnancy:

• Women with ectopic pregnancies may have atypical symptoms suggesting gastrointestinal or urinary tract dysfunction.
• Cornual pregnancies are rare but dangerous types of ectopic pregnancy. Clinicians should be aware of the difficulties with both clinical and ultrasound diagnosis.

• The risk of another ectopic pregnancy is about 10 to 20%.⁴
• The chance of subsequent intrauterine pregnancy is about 55 to 60%.⁴

Ectopic pregnancy does not occur in normal tubes, so prevention is based on avoiding the cause of damaged tubes. This includes avoiding promiscuity and activities that predispose to pelvic inflammatory disease and the early diagnosis and treatment of appendicitis. That is not to say that all PID is sexually transmitted but many of the infecting organisms, including Chlamydia are usually spread by that route. Routine screening of asymptomatic people for chlamydia may reduce the incidence of ectopic pregnancy¹³ but this is yet to be proved. City and Hackney has seen a decline in the rate of ectopic pregnancies during the 1990s but the reason is unclear.¹⁴ In Sweden, a reduction in the incidence of PID has been followed by a falling rate of ectopic pregnancy.¹⁵ The incidence of ectopic pregnancy in England and Wales rose between 1966 and 1996. This may be partly due to artefacts of data recording and more sensitive diagnostic tests, but it is likely that the actual incidence has increased, probably due to a sexually transmitted agent.¹⁶ The rate in the UK from 1991 until 2002 has been fairly static.¹