Ectopic pregnancy

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Chapter 9 Ectopic pregnancy

Michael Flynn

Definition. An ectopic pregnancy is implantation of a pregnancy outside the uterine cavity.

Incidence. Incidence varies with geographical location, from 1 in 28 to 1 in 300 pregnancies; 65% occur in the age group 25–34 years. In developed countries, incidence remains static at approximately 11 in 1000 pregnancies. Heterotrophic pregnancy (coexisting intrauterine and ectopic pregnancies) occurs in 1 in 30,000 spontaneous conceptions and in at least 1% of technically assisted conceptions.

Site. 97% of ectopic pregnancies occur in the fallopian tubes; the remainder are abdominal, ovarian or cervical.

Tubal ectopic pregnancy

Aetiology and risk factors

• pelvic inflammatory disease: associated with a seven-fold increased incidence of ectopic pregnancy
• tubal surgery
• past history of ectopic pregnancy: a 10%–15% chance of recurrence, rising to 50% if the contralateral tube is abnormal
• contraception associated with a risk of ectopic pregnancy

• progesterone-only pill
• postcoital pill
• intrauterine contraceptive device (users who fall pregnant have a higher risk of ectopic pregnancy than oral contraceptive users)

• assisted reproductive techniques: 5% of pregnancy cycles
• endometriosis
• abnormal embryo

Presentation

• amenorrhoea
• small amount of vaginal bleeding, often after the onset of pain
• lower abdominal pain, shoulder-tip pain
• cervical motion tenderness, adnexal tenderness/mass

Investigations

Quantitative serum human chorionic gonadotrophin (hCG)

From 10 days postfertilisation, the hCG level doubles every 48 hours. If there is an apparently inadequate rise in hCG levels, suspect a failed pregnancy or ectopic pregnancy. Up to 1% of ectopic pregnancies have hCG levels <25 IU/L.

Ultrasound

Intrauterine pregnancy can be identified by 6 weeks gestation via transabdominal ultrasound scan and by 5 weeks gestation when using transvaginal scans. Abdominal ultrasound scans should identify an intrauterine sac with hCG levels >2000 IU/L; with transvaginal scans, the intrauterine sac may be seen with hCG >1000 IU/L. If no intrauterine sac is present with these levels, ectopic pregnancy is suspected.

Other biochemical investigations

Decreased serum progesterone is a sensitive marker in ectopic pregnancies and non-viable intrauterine pregnancies.

Laparoscopy

This is the gold standard in investigation and diagnosis; 3%–4% of very early tubal pregnancies can be missed.

Management

Surgical (laparoscopic or open procedures)

A laparoscopic approach to surgical management in a stable patient is the preferred approach, with shorter hospital stays, no difference in tubal patency rates and lower repeat ectopic rates. There is no role for medical management in the face of haemodynamic compromise.

Salpingectomy and salpingostomy

• In those managed by removal of the ectopic tissue only, follow-up with weekly quantitative hCG test is required. At least 5% of these cases will have evidence of continuing trophoblastic activity (i.e. persistent ectopic pregnancy).
• There is no randomised control trial evidence specifically comparing salpingectomy and salpingostomy. Cohort studies suggest no difference in subsequent intrauterine pregnancy rates between either procedure, but a tendency towards higher subsequent ectopic pregnancies in the salpingostomy group.

Local injection of ectopic pregnancy

• methotrexate, potassium chloride, prostaglandins
• requires follow-up because of risk of persisting ectopic pregnancy

Medical

Systemic methotrexate

Single-dose methotrexate is successful in over 90% of cases. The dose is calculated on body surface area at 50 mg/m2. Criteria for use include:

• haemodynamic stability
• no fetal cardiac activity
• hCG level <15,000 IU/L
• ectopic mass ≤3.5 cm

About 15% will require a second dose if hCG levels have failed to fall more than 15% in 4–7 days. The outcome is comparable to that of surgery for unruptured ectopic pregnancy. It is useful for early cervical pregnancy, and has been used in continuing hCG activity after incomplete removal of an ectopic trophoblast.

Expectant management

This has been reported in the woman who does not have abdominal pain and who has falling hCG levels of <1000 IU/L. However, there have been cases of ruptured ectopic pregnancy with low and declining levels of hCG.

Anti-D

Rhesus-negative women with confirmed ectopic pregnancy should be given 250 IU of anti-D.

Contraception and future pregnancies

Because of the heightened risk of future ectopic pregnancies, the woman requires advice for subsequent pregnancies, such as an early hCG test and ultrasound scan.

Avoid contraception, which can increase the risk of ectopic pregnancies (e.g. progesterone-only pill, intrauterine contraceptive device).

Abdominal pregnancy

Incidence. Incidence is up to 1 in 10,000 live births. There is a higher incidence with low socioeconomic status and in developing countries.

Maternal mortality. 2%–10% of abdominal pregnancies (i.e. seven to eight times the risk compared with tubal ectopic pregnancies and 90 times the risk of intrauterine pregnancy).

Management

• If the fetus dies and a lithopedion develops, no treatment is required.
• If the fetus dies, wait 3–8 weeks to allow it to atrophy. However, coagulation disorders may develop.
• If the fetus is alive, intervene early because of the risk of maternal morbidity/mortality.
• Management of the placenta is debatable:

• If an attempt is made to remove it, there is a risk of bleeding.
• If the placenta is left in situ, there is a risk of infection and abscess formation.
• Treat with methotrexate.

Reference

Royal College of Obstetricians and Gynaecologists (RCOG). Guideline 21: The management of tubal pregnancy. RCOG: London; 2004.

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Chapter 9 Ectopic pregnancy

Michael Flynn

Definition. An ectopic pregnancy is implantation of a pregnancy outside the uterine cavity.

Incidence. Incidence varies with geographical location, from 1 in 28 to 1 in 300 pregnancies; 65% occur in the age group 25–34 years. In developed countries, incidence remains static at approximately 11 in 1000 pregnancies. Heterotrophic pregnancy (coexisting intrauterine and ectopic pregnancies) occurs in 1 in 30,000 spontaneous conceptions and in at least 1% of technically assisted conceptions.

Site. 97% of ectopic pregnancies occur in the fallopian tubes; the remainder are abdominal, ovarian or cervical.

Tubal ectopic pregnancy

Aetiology and risk factors

• pelvic inflammatory disease: associated with a seven-fold increased incidence of ectopic pregnancy
• tubal surgery
• past history of ectopic pregnancy: a 10%–15% chance of recurrence, rising to 50% if the contralateral tube is abnormal
• contraception associated with a risk of ectopic pregnancy

• progesterone-only pill
• postcoital pill
• intrauterine contraceptive device (users who fall pregnant have a higher risk of ectopic pregnancy than oral contraceptive users)

• assisted reproductive techniques: 5% of pregnancy cycles
• endometriosis
• abnormal embryo

Presentation

• amenorrhoea
• small amount of vaginal bleeding, often after the onset of pain
• lower abdominal pain, shoulder-tip pain
• cervical motion tenderness, adnexal tenderness/mass

Investigations

Quantitative serum human chorionic gonadotrophin (hCG)

From 10 days postfertilisation, the hCG level doubles every 48 hours. If there is an apparently inadequate rise in hCG levels, suspect a failed pregnancy or ectopic pregnancy. Up to 1% of ectopic pregnancies have hCG levels <25 IU/L.

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