Spontaneous abortion (aka miscarriage) is the ultimate fate of 15 - 20% of all pregnancies. A spontaneous abortion is the early termination of a pregnancy by natural causes prior to fetal extrauterine viability (20 wks; (1)). Most often, spontaneous abortions are idiopathic, though they may also be caused by chromosomal abnormalities or infection in the fetus, an anembryonic gestation (aka blighted ovum), an abnormal environment, maternal infection, maternal debilitating disease, malnutrition, poor implantation, uterine abnormality, drugs, or radiation.
There are several types of abortion:
When looking for gross or microscopic symptoms of abortion, one looks for the products of conception. Microscopically, these include villi, trophoblast, fetal parts, and background gestational changes in the endometrium.