Histology and Ureaplasma urealyticum culture in 63 cases of first trimester abortion

The association between chorioamnionitis caused by Ureaplasma urealyticum and preterm delivery has been well documented. In contrast, a pathogenic role for Ureaplasma has been postulated in early spontaneous abortions, but definitive evidence for this association has been lacking. In 42 early spontaneous abortions and 21 elective abortions (both first trimester), the chorion was cultured for Ureaplasma. Each case was evaluated histologically for four features of inflammation and one feature of degeneration. For comparison, 32 selected placentas from third trimester preterm deliveries (11 with positive Ureaplasma cultures) were examined histologically for umbilical vasculitis and acute chorioamnionitis. In abortion specimens, Ureaplasma cultures were positive in 11 of 42 early spontaneous abortions (26%) versus 0 of 21 elective abortions (EABs). None of the five histologic features correlated with positive Ureaplasma cultures in early spontaneous abortions. In contrast, in preterm placentas, umbilical vasculitis, and acute chorioamnionitis correlated strongly with positive Ureaplasma cultures. The authors conclude that in premature delivery, U urealyticum chorionic culture positivity is associated with histologic chorioamnionitis; and in abortions, Ureaplasma chorionic culture positivity correlates with early spontaneous abortions (vs elective abortions), but not with histologic inflammation. This suggests that mechanisms of Ureaplasma pathogenesis other than acute inflammation should be considered in future studies of early spontaneous abortions.