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EPIDEMIOLOGY

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). Rare, bilateral ectopic pregnancies have been described (al-Awwad, 1999).

FIGURE 7-1

Various sites and frequency of ectopic pregnancies.

The reported incidence of ectopic pregnancy is usually calculated as the number of treated cases divided by the total of all pregnancies. Nationally, the rates in 2013 from one large private insurance database and from Medicaid claims were 1.54 percent and 1.38 percent, respectively (Tao, 2017). Stulberg and coworkers (2014) reviewed Medicaid data from 2004 to 2008 from 14 states and found a similar national rate.

Although ectopic pregnancy accounts for a small proportion of all pregnancies, it disparately accounts for 3 percent of all pregnancy-related deaths (Creanga, 2017). Still, current diagnostic and treatment protocols have substantially lowered 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 (Creanga, 2011). From the same Medicaid database noted earlier, Stulberg and coworkers (2016) noted that 53 percent of ectopic-related deaths occurred in black women. Inadequate access to gynecologic and prenatal care may partially explain this trend.

RISK FACTORS

Several risks have been linked with ectopic pregnancy. As shown in Table 7-1, abnormal fallopian tube anatomy that alters normal embryo transport underlies most cases. For example, prior tubal pregnancy raises risks. In one study of more than 1000 treated ectopic pregnancies, the recurrence rate was 10 percent (de Bennetot, 2012). Surgeries for fertility restoration, for ectopic pregnancy, or for sterilization also confer a higher risk.

TABLE 7-1Risk Factors for Ectopic Pregnancy

Pelvic inflammatory disease (PID) originating from Neisseria gonorrhoeae or Chlamydia trachomatis is a potent risk factor for tubal injury and ectopic pregnancy. Recurrent ...

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