Table 1.

Terminology Related to Abortion

• Abortion—Disruption of an embryo or fetus implanted in the uterus. Abortions may be spontaneous or induced. A pregnancy does not begin until after the implantation of the blastocyst, ∼7 d after fertilization.

• Induced abortion—An abortion that is deliberately caused for elective or therapeutic medical reasons.

• Spontaneous abortion—An abortion that is not induced but occurs without obvious external cause. Most spontaneous abortions—especially early in pregnancy—are the result of lethal genetic defects in the developing embryo. The death of the embryo or fetus before 20 wk of gestation is usually classified as a spontaneous abortion, whereas after 20 wk of gestation it is usually classified as a stillbirth or intrauterine fetal death. Induced abortions are referred to as abortions at all gestational ages.

• Threatened abortion—Vaginal bleeding occurring before 20 wk of gestation without dilatation of the cervix, indicating that a spontaneous abortion may be about to occur.

• Inevitable abortion—Vaginal bleeding occurring before 20 wk of gestation with rupture of the amniotic membranes and/or dilatation of the cervix.

• Incomplete abortion—An abortion in which some, but not all, of the products of conception (including placenta and amniotic membranes) remain in the uterus. Women with incomplete abortions are at increased risk of infection or hemorrhage if the products of conception are not removed promptly.

• Complete abortion—An abortion in which all of the products of conception have been expelled.

• Missed abortion—A pregnancy in which the death of the embryo or fetus has occurred but which has not yet caused bleeding. In early pregnancy, this is sometimes also referred to as a blighted ovum or an anembryonic pregnancy. The term intrauterine fetal death is also used, depending on the gestational age.

• Septic abortion—Infection of the uterus and its contents before, during, or after an abortion (either spontaneous or induced). In such cases, systemic sepsis may develop explosively, progressing rapidly to septic shock. If not treated promptly and effectively, a fatal outcome may result.

• Chorioamnionitis—Infection of the amniotic fluid and fetal membranes (chorion and amnion), usually arising from an ascending polymicrobial infection from the lower genital tract, especially when the membranes have ruptured. Subclinical chorioamnionitis is often suspected as a cause of premature labor or spontaneous abortion.