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Introduction

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Following fertilization and fallopian tube transit, the blastocyst normally implants in the endometrial lining of the uterine cavity. Implantation elsewhere is considered ectopic and comprises 1 to 2 percent of all first-trimester pregnancies in the United States. This small proportion disparately accounts for 6 percent of all pregnancy-related deaths (Berg, 2010; Stulberg, 2013). In addition, the chance for a subsequent successful pregnancy is reduced after an ectopic pregnancy. Fortunately, urine and serum beta-human chorionic gonadotropin (β-hCG) assays and transvaginal sonography have made earlier diagnosis possible. And as a result, both maternal survival rates and conservation of reproductive capacity are improved.

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Tubal Pregnancy

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Classification
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Nearly 95 percent of ectopic pregnancies are implanted in the various segments of the fallopian tube and give rise to fimbrial, ampullary, isthmic, or interstitial tubal pregnancies (Fig. 19-1). As shown, the ampulla is the most frequent site, followed by the isthmus. The remaining 5 percent of nontubal ectopic pregnancies implant in the ovary, peritoneal cavity, cervix, or prior cesarean scar. Occasionally, a multifetal pregnancy is composed of one conceptus with normal uterine implantation coexisting with one implanted ectopically. The natural incidence of these heterotopic pregnancies approximates 1 per 30,000 pregnancies. However, because of assisted reproductive technologies (ART), their incidence has increased to 1 in 7000 overall, and following ovulation induction, it may be as high as 0.5 to 1 percent (Mukul, 2007). Rarely, twin tubal pregnancy with both embryos in the same tube or with one in each tube has been reported (Eze, 2012; Svirsky, 2010).

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Figure 19-1

Sites of implantation of 1800 ectopic pregnancies from a 10-year population-based study. (Data from Callen, 2000; Bouyer, 2003.)

Graphic Jump Location
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Regardless of location, D-negative women with an ectopic pregnancy who are not sensitized to D-antigen should be given IgG anti-D immunoglobulin (American College of Obstetricians and Gynecologists, 2013). In first-trimester pregnancies, a 50-μg or a 300-μg dose is appropriate, whereas a standard 300-μg dose is used for later gestations.

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Risks
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Abnormal fallopian tube anatomy underlies many cases of tubal ectopic pregnancy. Surgeries for a prior tubal pregnancy, for fertility restoration, or for sterilization confer the highest risk of tubal implantation. After one previous ectopic pregnancy, the chance of another approximates 10 percent (Ankum, 1996; Skjeldestad, 1998). Prior sexually transmitted disease or other tubal infection, which can distort normal tubal anatomy, is another common risk factor. Specifically, one episode of salpingitis can be followed by a subsequent ectopic pregnancy in up to 9 percent of women (Westrom, 1992). Similarly, peritubal adhesions subsequent to salpingitis, appendicitis, or endometriosis may increase the risk for tubal pregnancy. Salpingitis isthmica nodosa, which is a condition in which epithelium-lined diverticula extend into ...

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