• First trimester fetus within opened amniotic sac.

• Richly vascular placenta completely surrounds opening of sac.

• Chromosomal abnormalities including triploidy, trisomy (reported for every chromosome), monosmy X (Turner^s syndrome), among others.

• Problems with mainintaing implantation including antiphospholipid antibody syndrome

• Unknown

• Chromosomal abnormalities may result in fetal death with subsequent death of the placenta.

• Unknown what effect chromosomal abnormalities have on the placenta^s function.

• Antiphospholipid antibody syndrome is associated with abnormal decidual vascularization and thrombosis of decidual vessels with abruption.

• Ascending infection leads to membrane rupture and premature delivery.

• Anatomic cervical incompetence can also lead to miscarriage.

• Human pregnancy generates large numbers of spontaneous losses.

• Estimates of the percentages of conceptions that fail to reach term has increased with the advent of early detection methods.

• Greater than 25% of pregnancies end spontaneously.

• Current estimates are that approximately 50% of first trimester losses (by far the most common) are secondary to chromosomal abnormalities.

• Increasing spontaneous abortion rate with age.

• Some women are habitual aborters.

• Most women are not habitual aborters.

• An attempt to categorize the miscarriage as either secondary to chromosomal abnormalities or euploidy is useful in the management of women with recurrent losses.

• Aneuploid losses may repeat with advanced maternal age. Also will repeat if parent carries a balanced translocation (very rare).

• Euploid losses may repeat but intervention with aspirin and/or heparin may permit maintenance of a subsequent pregnancy to viability.

• An empty sac or disorganized embryonic tissues (identified by microscopy) may be secondary to early fetal demise.

• Alternatively the fetus may be delivered within the amnionic sac followed by the placenta.

• Findings vary with etiology of the loss.

• Common to all is an implantation site with acute hemorrhage and inflammation.

• Decidualized endometrium is generally sloughed as well.

• The villi may show infarct or intervillositis in cases associated with euploidy.

• The villi may show a complex villus outline, trophoblastic inclusions, and calcifications in aneuploid gestations.

• Histologic abnormalities can be demonstrated in the fetus.

• Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 1078-9.

• Current literature from PubMed at National Library of Medicine