HUMAN-FETAL OXYGENATION FOLLOWING PARACERVICAL-BLOCK

To test the hypothesis that fetal heart rate (FHR) changes following paracervical block may be secondary to fetal hypoxia, human fetal oxygenation was measured continuously using a transcutaneous electrode. Following the bloc,, each fetus demonstrated a decline in oxygen tension (tcPo2) at 5 minutes, which reached its lowest value at a mean of 11.5 minutes and remained at this level for an average of 3 minutes. Following the block, FHR variability increased at 5.2 minutes, reaching its maximal level by a mean of 7.5 minutes. By 11 minutes, a decrease in FHR variability was noted, which lasted for approximately 17 minutes. Decreased variability was not uniformly associated with low tcPo2. On some occasions, fetal tcPo2 declined even in the absence of increased uterine activity, which was noted at times following the block. The severity of the tcPo2 decline appears related to the analgesic effectiveness of the block. © 1979.