Doppler studies of the placental and fetal circulation in pregnancies with preterm prelabor amniorrhexis.

This study has investigated the effect of intrauterine infection on placental perfusion, fetal circulation and fetal oxygenation in patients with preterm prelabor amniorrhexis. In 69 pregnancies with preterm prelabor amniorrhexis, Doppler ultrasound studies of the uterine and umbilical arteries and the fetal middle cerebral artery and thoracic aorta were performed. Within 1 h after the Doppler studies, cordocentesis and amniocentesis were carried out for microbiological investigations and measurement of blood pO2 and pH. In the amniorrhexis group, there were no significant differences from the appropriate normal mean for gestation in any of the Doppler indices or blood gas results. Furthermore, there were no significant differences between the groups with positive fetal blood or amniotic fluid cultures and those with no evidence of infection. These data demonstrate that, in preterm prelabor amniorrhexis, microbial invasion of the amniotic cavity and fetal bacteremia are not associated with detectable changes in placental perfusion, fetal circulation or fetal oxygenation.