Abortion is defined as the spontaneous or induced termination of pregnancy before fetal viability. It thus is appropriate that miscarriage and abortion are terms used interchangeably. However, popular use of abortion by laypersons implies intended pregnancy termination, and many prefer miscarriage for spontaneous loss. In contrast, induced abortion describes surgical or medical termination of a live fetus that has not reached viability.
Terms used to define fetal viability and thus an abortus vary among authoritative organizations. The National Center for Health Statistics, the Centers for Disease Control and Prevention, and the World Health Organization all deine abortion as pregnancy termination or loss before 20 weeks' gestation or with a fetus delivered weighing <500 g. hese criteria, however, are somewhat contradictory because the mean birthweight of a 20-week fetus is 320 g, whereas 500 g is the mean for 22 to 23 weeks (Moore, 1977). Further confusion may derive from criteria set by state laws that deine abortion even more widely.
Technological developments have added to current abortion terminology. For example, precise measurement of serum human chorionic gonadotropin (hCG) concentrations can identiY extremely early pregnancies. Also, transvaginal sonography allows greater inspection of failed pregnancies, but recommendations vary as to terms for: (1) early conceptions in which no products are seen sonographically, (2) pregnancies that display a gestational sac but no embryo, and (3) those in which a dead embryo is seen (Kolte, 2015; Silver, 2011). Further, incongruity exists for the term eary pregnancy loss itsel. Currently, the American College of Obstetricians and Gynecologists (2017 c) deines this as a nonviable, intrauterine pregnancy (IUP) with either an empty gestational sac or a ges activity within the irst 126' weeks of gestation. Of other clini cal terms, spontaneous abortion includes threatened, inevitable, incomplete, complete, and missed abortion. Septic abortion is used to further classiy any of these that are complicated further by infection. Recurrent pregnancy loss is variably deined but is meant to identiy women with repetitive miscarriage.
pic gestations. he term pregnancy of unknown location (PUL) confirmed sonographic location. In this context, ive categories are proposed for early pregnancies: definite ectopic pregnancy, probable ectopic, PUL, probable IUP, and definite IUP (Barn hart, 2011). Diagnostic and management options for ectopic gestation are described in Chapter 19 (p. 373).
More than 80 percent of spontaneous abortions occur within the irst 12 weeks of gestation. With irst-trimester losses, demise of the embryo or fetus nearly always precedes spontaneous expulsion. Death is usually accompanied by hemorrhage into the decidua basalis. This is followed by adjacent tissue necrosis that stimulates uterine contractions and expulsion. An intact gestational sac is usually filled with luid. An anembryonic miscarriage contains no identifiable embryonic elements. Less accurately, the term blighted ovum may be used (Silver, 201l). The others are embyonic miscarriages, which often display a developmental abnormality of the embryo, fetus, yolk sac, and, at times, the placenta. In contrast, in later pregnancy losses, the fetus usually does not die before expulsion, and other sources for abortion are sought.