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Williams Obstetrics, 22e
| Section III. Antepartum > |
Pathogenesis of Ectopic Pregnancies
Sections: Tubal Pregnancy, Tubal Abortion, Tubal Rupture, Abdominal Pregnancy, Broad-Ligament Pregnancy, Interstitial Pregnancy, Multifetal Ectopic Pregnancy, Heterotypic Ectopic Pregnancy, Multifetal Tubal Pregnancy, Tubo-Uterine, Tubo-Abdominal, and Tubo-Ovarian Pregnancies.
Topics Discussed: abortion, tubal; ectopic pregnancy; ectopic pregnancy, ruptured; lithopedian; pregnancy, abdominal; pregnancy, broad ligament; pregnancy, interstitial; pregnancy, tubal; tubal pregnancy, ruptured.
Excerpt:
"The fertilized ovum may lodge in any portion of the
oviduct, giving rise to ampullary, isthmic, and interstitial tubal
pregnancies (see Fig. 2–13). In rare instances, the fertilized ovum
may implant in the fimbriated extremity. The ampulla is the most frequent
site, followed by the isthmus. Interstitial pregnancy accounts for only
about 3 percent of all tubal gestations. From these primary types, secondary
forms of tubo-abdominal, tubo-ovarian, and broad-ligament pregnancies
occasionally develop.If only the fetus is extruded at the time of
rupture, the effect on the pregnancy will vary, depending on the extent of
injury sustained by the placenta. The fetus dies if the placenta is damaged
appreciably, but if the greater portion of the placenta retains its tubal
attachment, further development is possible. The fetus may then survive for
some time, giving rise to an abdominal pregnancy. Typically in such cases, a
portion of the placenta remains attached to the tubal wall and the periphery
grows beyond the tube and implants on surrounding structures.Tubal pregnancy may be accompanied by a
coexisting uterine gestation. Until recently, such heterotypic pregnancies
were rare, with an incidence..."
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