Obstetrics and Gynecology/Ectopic Pregnancy

Ectopic Pregnancy is a life-threatening condition characterised by the implantation of an embryo outside the uterine cavity, usually in the fallopian tube.

Epidemiology

The incidence of ectopic pregnancy is increasing in the UK and currently stands at 1 in 100 pregnancies.

Risk Factors

• Increased maternal age
• Smoking
• Previous tubal surgery
• Prior recurrent spontaneous miscarriages
• Prior surgical termination of pregnancy
• Pelvic inflammatory disease
• Previous use of an intrauterine device
• History of infertility

Prior oral contraception use can reduce the risk of ectopic pregnancy.

Etiology and Pathogenesis

When the ovum is released by the ovary, it travels along the fallopian tube (where it is fertilized) in the direction of the uterus. The resulting embryo does not reach its destination, however, as it implants into the wall of the fallopian tube. The subsequents trophoblastic proliferation causes erosion and bleeding. Unlike the uterus, the fallopian tube's muscle layer does not undergo hypertrophy, so rupture into the lumen and peritoneal and retroperitoneal cavities occurs.

Clinical Features

History

• Severe lower abdominal colicky pain
• Vaginal bleeding after a missed period
• Shoulder tip pain
• Dysuria
• Shock

Examination

• Signs of early pregnancy
• Mass on vaginal examination
• Soft, enlarged uterus
• Cervical excitation
• Abdominal tenderness

Investigations

• Pregnancy test and serum β-hCG
• Ultrasound scan - trans-vaginal

Treatment

Treat these patients as resuscitation patients. Give oxygen and gain IV access. Cross-match blood and request Rhesus status. Surgery is avoided initially using IV methotrexate and hCG monitoring. If the pregnancy continues, surgical intervention is required.

References

Why women die. Report on confidential enquiries into maternal deaths in the United Kingdom 1994-1996. Norwich: Stationery Office, 1998. The risk factors for an ectopic pregnancy are:

Bouyer J et al. Risk Factors for Ectopic Pregnancy: A Comprehensive Analysis Based on a Large Case-Control, Population-based Study in France. Am J Epidemiol 2003 157;185-194

O'Connor, J. Pathology 2nd ed. Mosby. Edinburgh. 2002.

McCarthy, A & Hunter, B (2003) Master Medicine: Obstetrics and Gynaecology (2nd ed.) Philadelphia: Elsevier Saunder

http://www.gpnotebook.co.uk