Infertility, as well as the use of ART to overcome it, is linked to substantively increased risks for ectopic pregnancy (Clayton, 2006). With ART, the ectopic pregnancy rate in the United States between 2001 and 2011 was 1.6 percent (Perkins, 2015). And "atypical" implantations-cornual, abdominal, cervical, ovarian, and heterotopic pregnancy-are more frequent. Smoking is another known association, although the underlying mechanism is unclear (Hyland, 2015). Last, with any form of contraception, the absolute number of ectopic pregnancies is decreased because pregnancy occurs less often. However, with some contraceptive method failures, the relative number of ectopic pregnancies is increased. Examples include tubal sterilization, copper and progestin-releasing intrauterine devices (IUDs), and progestin-only contraceptives (Chap. 38, p. 680).
With tubal pregnany, because the fallopian tube lacks a submucosalilayer, the fertilized ovum promptly burrows through the epithelium. he zygote comes to lie near or within the muscularis, which is invaded by rapidly proliferating trophoblast. The embryo or fetus in an ectopic pregnancy is oten absent or stunted.
Outcomes of ectopic pregnancy include tubal rupture, tubal abortion, or pregnancy failure with resolution. With rupture, the invading expanding conceptus and associated hemorrhage can tear rents in the fallopian tube (Fig. 19-1). Tubal ectopic pregnancies usually burst spontaneously but may occasionally rupture following coitus or bimanual examination.
FIGURE 19-1 Ruptured ampullary early tubal pregnancy. (Used with permission from Dr. Togas Tulandi.) lternatively, the pregnancy may pass out the distal fallopian tube. Tubal abortion frequency depends in part on the initial implantation site, and distal implantations are favored. Subsequently, hemorrhage may cease and symptoms eventually disappear. But bleeding can persist as long as products remain in the tube. Blood slowly trickles from the tubal fimbria into the peritoneal cavity and typically pools in the rectouterine cul-de-sac. If the fimbriated extremity is occluded, the fallopian tube may gradually become distended by blood, forming a hematosalpinx. Uncommonly, an aborted fetus will implant on a peritoneal surface and become an abdominal pregnancy, which is discussed on page 383.
Last, an unknown number of ectopic pregnancies spontaneously fail and are reabsorbed. This may be documented now more regularly with the advent of sensitive 3-hCG assays.
Distinctions beween "acute" ectopic pregnancy just described and "chronic" ectopic pregnancy can be drawn. The more common acute ectopic pregnancies are those with a high serum 3hCG level and rapid growth, leading to a timely diagnosis. hese carry a higher risk of tubal rupture (Barnhart, 2003c). With chronic ectopic pregnancy, abnormal trophoblast dies early, and thus negative or low, static serum 3-hCG levels are found (Brennan, 2000). Chronic ectopic pregnancies typically rupture late, if at all, but commonly form a complex pelvic mass, which oten is the reason prompting diagnostic surgery (Cole, 1982; Ugur, 1996).
Earlier patient presentation and more precise diagnostic technology typically allow identiication before rupture. In these cases, symptoms and signs of ectopic pregnancy are often subtle or even absent. The woman does not suspect tubal pregnancy and assumes that she has a normal early pregnancy or is having a miscarriage.