[Semi-quantitative evaluation of the intrapartum variable deceleration of the FHR pattern and its association with umbilical cord blood gas analysis].

Variable daceleration of FHR combined with no other abnormal pattern was semi-quantitatively evaluated to establish the diagnostic value of variable deceleration for fetal distress. FHR charts of 55 low risk vaginal deliveries by direct monitoring were analysed and the SDA (Sum of Dip Area) was calculated using the following equation: SDA = sigma Duration of dip (sec.) X Amplitude of dip (bpm.) X 10(-2) and correlation between SDA and umbilical cord blood gas analysis was obtained. A significant correlation was observed between SDA during labor (from 5 cm cervical dilation to delivery) and cord blood gas data. pHuv:r = -0.445 (p less than 0.005), PO2uv:r = -0.358 (p less than 0.01), BEuv:r = -0.538 (p less than 0.001), pHua:r = -0.441 (p less than 0.005), BEua:r = -0.463 (p less than 0.001). In 14 cases which showed prolonged deceleration (PD:more than 120 sec. in duration and below 100 bpm. in dip), excellent correlation was observed between the SDA of PD and pHuv:pHuv = 7.425-7.74 X 10(-4) SDA of PD (r = -0.756, p less than 0.005), whereas in 21 cases with severe variable deceleration (SVD:more than 60 sec. and recovered within 120 sec. in duration or below 60 bpm. in dip) no significant correlation was seen between the SDA of SVD and pHuv. These results suggest that the SDA value is helpful in evaluating variable deceleration during labor.