Ectopic Pregnancy

Description

Ectopic: pregnancy implanted outside 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 of pregnancy in cervix
• Intraligamentary: implantation of pregnancy within the broad ligament

Epidemiology

• 108,800 cases in 1992 in the United States, according to CDC census (most recent data available), meaning that 1.5–2.0% of all pregnancies were ectopic. The true incidence is difficult to estimate.
• In the United States, ectopic pregnancy is the leading cause of 1st trimester maternal deaths and accounts for 6% of all pregnancy-related deaths.
• Heterotopic pregnancy, although rare (1:30,000), occurs with greater frequency in women undergoing in vitro fertilization (IVF) (1/1,000).
• Increasing incidence of nontubal, and particularly cesarean scar ectopic pregnancies, due in part to more cesarean sections and more IVF

Prevalence
~33% recurrence rate if prior ectopic pregnancy

Etiology and Pathophysiology

• 95–97% of ectopic pregnancies occur in the fallopian tube, of which, 55–80% in the ampulla, 12–25% in the isthmus, and 5–17% in the fimbria.
• One risk factor for a tubal pregnancy is impaired movement of the fertilized ovum to the uterine cavity due to dysfunction of the tubal cilia, scarring, or narrowing of the tubal lumen.
• Other locations are rare but may occur from reimplantation of an aborted tubal pregnancy or from uterine structural abnormalities (mainly cervical pregnancy).

Risk Factors

• History of pelvic inflammatory disease (PID), endometritis, or current gonorrhea/chlamydia infection
• Previous ectopic pregnancy
• History of tubal surgery (~33% of pregnancies after tubal ligation will be ectopic.)
• Pelvic adhesive disease (infection or prior surgery)
• Use of an intrauterine device (IUD): Overall chance of any pregnancy 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
• Maternal diethylstilbestrol (DES) exposure in utero (DES was last used in 1972.)
• Tobacco use
• Patients with disorders that affect ciliary motility may be at increased risk (e.g., endometriosis, Kartagener).

General Prevention

• Reliable contraception or abstinence
• Screening for and treatment of STIs (i.e., gonorrhea, chlamydia) that can cause PID and tubal scarring