An ectopic or extrauterine pregnancy is one in which the blastocyst implants anywhere other than the endometrial lining of the uterine cavity. As such, they account for 1 to 2 percent of reported pregnancies in the United States (Zane, 2002). With the advent of a sensitive and specific radioimmunoassay for the β-subunit of human chorionic gonadotropin (β-hCG), combined with high-resolution transvaginal sonography (TVS), the initial presentation of a woman with an ectopic pregnancy is seldom as life-threatening as in the past. Nevertheless, ectopic pregnancies remain an important cause of morbidity and mortality in the United States.
Nearly 95 percent of ectopic pregnancies implant in the fallopian tube. Shown in Figure 7-1 are implantation sites for 1800 surgically treated ectopic pregnancies (Bouyer, 2002). Bilateral ectopic pregnancies are rare, and their estimated prevalence is 1 of every 200,000 pregnancies (al-Awwad, 1999).
Various sites and frequency of ectopic pregnancies. (From Cunningham, 2010, with permission.)
Reported ectopic pregnancy incidence rates are not as reliable as in the past. The dramatic improvements in diagnosis and outpatient treatment protocols render national hospital discharge statistics invalid. According to the Centers for Disease Control and Prevention (1995), the rate of ectopic pregnancy has increased in the United States nearly fourfold from 4.5 per 1000 pregnancies in 1970 to 19.7 per 1000 pregnancies in 1992. This rate is similar to recent estimates by Kaiser Permanente of North California of 20.7 per 1000 pregnancies from 1997 to 2000 (Van Den Eeden, 2005). More recently, Hoover and colleagues (2010) queried a large claims database for women aged 15 to 44 who were privately insured in the United States between 2002 and 2007 and calculated a rate of 6.4 per 1000 pregnancies. However, this reported reduction in ectopic pregnancy rate may not accurately reflect the cases occurring in higher-risk, lower-socioeconomic, uninsured populations.
A number of factors help to explain the increased incidence of ectopic pregnancies:
Greater prevalence of sexually transmitted diseases, specifically chlamydial infections (Rajkhowa, 2000)
Diagnostic tools with improved sensitivity
Tubal factor infertility, including restoration of tubal patency or documented tubal pathology (Ankum, 1996)
Women with delayed childbearing and their accompanied use of assisted reproductive technologies, which carry increased risks of ectopic pregnancy
Increased intrauterine device (IUD) use and tubal sterilization, which predispose to ectopic pregnancy with method failure (Mol, 1995).
Ectopic pregnancy remains the leading cause of early pregnancy-related death. Still, current diagnostic and treatment protocols have resulted in a 10-fold decline in the case fatality rate during the past 35 years. The rate in 1970 was 35 deaths per 10,000 ectopic pregnancies compared with 4 per 10,000 in 1989. This was despite the fivefold increase in ectopic pregnancy rates from 17,800 ...