Description

Ectopic: Pregnancy implanted outside the confines of the uterine cavity. Subtypes include:

• Tubal: Pregnancy implanted in any portion of the fallopian tube
• Abdominal: Pregnancy implanted intra-abdominally, most commonly after tubal abortion or rupture of tubal ectopic pregnancy
• Heterotopic: Pregnancy implanted intrauterine and a separate pregnancy implanted outside uterine cavity
• Ovarian: Implantation of pregnancy in ovarian tissue
• Cervical: Implantation in cervix
• Intraligamentary: Implantation of pregnancy within the broad ligament

Epidemiology

• 108,800 cases in 1992 in the US according to CDC census (most recent data available) meaning that 1.5–2% of all pregnancies were ectopic (1). The leading cause of 1st-trimester maternal deaths, and accounts for 6% of all US pregnancy deaths.
• 20,000 hospitalizations reported in 2009 in the US for ectopic pregnancy
• Heterotopic pregnancy, although rare (1:30,000), occurs with greater frequency in women undergoing in vitro fertilization (IVF) (1–2/1,000).

Prevalence
5–20% recurrence rate if prior ectopic pregnancy (2)

Risk Factors

• History of tubal surgery (~15% of pregnancies after tubal ligation will be ectopic)
• Previous ectopic pregnancy
• History of pelvic inflammatory disease (PID), endometritis, or current gonorrhea/chlamydia infection
• Pelvic adhesive disease (infection, prior surgery)
• Use of an intrauterine device: Overall chance of pregnancy of any type with an IUD is low, however there is an increased likelihood of ectopic location if pregnancy occurs. IUDs reduce absolute risk of ectopic pregnancy.
• Use of assisted reproductive technologies (e.g., in vitro fertilization)
• Diethylstilbestrol exposure in utero (DES was last used in 1972)
• Cigarette smoking
• Patients with disorders that affect ciliary motility may be at increased risk (e.g., endometriosis).

General Prevention

• Reliable contraception or abstinence
• Screening and treatment of STDs (gonorrhea, chlamydia) that can cause PID and tubal scarring

Pathophysiology

• 98% of ectopic pregnancies occur in the fallopian tube (2); 55% in the ampullary portion of the tube, 25% in the isthmus, 17% in the fimbria.
• Of the remaining 2%, most are either ovarian, cervical, or abdominal pregnancies.

Etiology

• For a tubal pregnancy, impaired movement of the fertilized ovum to the uterine cavity due to dysfunction of the tubal cilia or due to scarring or narrowing of the tubal lumen
• Other locations are rare and may occur from reimplantation of an aborted tubal pregnancy or from uterine structural abnormalities (mainly cervical pregnancy).