An ectopic or extrauterine pregnancy is one in which the blastocyst implants anywhere other than the endometrial lining of the uterine cavity. Nearly 95 percent of ectopic pregnancies implant in the fallopian tube. Other sites are shown in Figure 7-1, which reflects data from 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. (Reproduced with permission from Cunningham FG, Leveno KJ, Bloom SL (eds): Ectopic pregnancy. In Williams Obstetrics, 24th ed. New York, McGraw-Hill Education, 2014.)
Reported incidences rates of ectopic pregnancy are less reliable than in the past as outpatient treatment protocols render national hospital discharge statistics invalid. One estimate by Kaiser Permanente of North California was 2.07 percent of total pregnancies from 1997 to 2000 (Van Den Eeden, 2005). Hoover and colleagues (2010) queried a large claims database of privately insured women between 2002 and 2007 and calculated a rate of 0.64 percent. However, this may not accurately reflect the cases in higher-risk, lower-socioeconomic, uninsured populations. Stulberg and coworkers (2014) reviewed 2004 to 2008 Medicaid claims data from 14 states. They reported a rate of 1.4 percent and noted that black women were 46 percent more likely to experience an ectopic pregnancy than whites in this government-insured group.
Among several factors that help explain the incidence of ectopic pregnancies are: (1) greater sexually transmitted disease prevalence, (2) diagnostic tools with improved sensitivity, (3) tubal factor infertility, (4) delayed childbearing and accompanied use of assisted reproductive technology, and (5) increased intrauterine device (IUD) use and tubal sterilization, which predispose to ectopic pregnancy if the method fails (Ankum, 1996; Li, 2014a; Ljubin-Sternak, 2014).
Ectopic pregnancy remains the leading cause of early pregnancy-related death. Still, current diagnostic and treatment protocols have resulted in substantial declines in fatality rates. One analysis showed a 56-percent decline in the ectopic pregnancy mortality ratio between the 1980 to 1984 epoch and the 2003 to 2007 epoch. During this later span, African-American women were approximately three times more likely to die as a result of ectopic pregnancy complications than whites (Creanga, 2011). Inadequate access to gynecologic and prenatal care may partially explain this trend.
In most of these cases, death is directly related to severe hemorrhage from tubal rupture. Risk factors that increase the likelihood of tubal rupture include ovulation induction, serum β-human chorionic gonadotropin (β-hCG) level >10,000 IU/L, and never having used contraception (Job-Spira, 1999). Appreciation of these characteristics can aid prompt surgical intervention.
Several risks have been linked with ectopic pregnancy (Table 7-1). Among these, documented tubal pathology, surgery ...