Placental pathology in midtrimester pregnancies interrupted by intra-amniotic injection of hypertonic urea.

The histological appearances of 52 placentae from patients who had a urea-induced second trimester abortion were studied. Extensive subchorionic intervillous fibrin deposition and swollen degenerated stromal cells (probably Hofbauer cells), were found both in the placenta and membranes. Between urea injection and abortion, serial vaginal smears showed signs of progesterone deficiency. The urea-induced placental and fetal damage was similar to that seen with hypertonic saline.