Placental examination in a clinical setting.

Placental examination has been proved to be of clinical value in cases selected because of gestational complications, unusual disorders of mother or infant, perinatal death, problems in perinatal diagnosis, and multiple pregnancy. Ten percent to 15% of births meet these criteria for selection. Causes of perinatal death, such as placental abruption, cord accidents, placental infarction, infection, and hematologic disorders, have been demonstrated. Clinically occult abnormalities, including chronic infections, maternal vascular disease, neoplasms, and storage diseases, have been recognized. Amniotic lesions and single umbilical artery have directed attention to fetal malformations. Monozygosity has been documented by monochorionic placentation. As a diagnostic source, the placenta has contributed to clinical care, understanding of disabilities among surviving children, and insight of forensic value. Limitations of placental studies stem from their qualitative nature and from gaps in current knowledge of gestational pathophysiology.