Relationship between resistance index and peak systolic velocity of middle cerebral artery with fetal heart rate in doppler sonography

Considering the importance of evaluating resistance index (RI) and peak systolic velocity (PSV) of fetal middle cerebral artery (MCA) in determining fetal distress and fetal diseases such as anemia, this study was performed with aim to investigate the effect of changes in fetal heart rate (FHR) during resting and activity on RI and PSV indices of fetal MCA. This analytical cross-sectional study was performed by sampling method on 192 pregnant women with gestational age of 16-39 weeks referred to Kermanshah Imam Reza Hospital in 2016. Doppler ultrasound was performed in two fetal resting and activity states, and MCA-RI, MCA-PSV and FHR level were measured. Data analysis was performed by SPSS software (version 22) and Wilcoxon and paired t-tests. P<0.05 was considered statistically significant. According to the results, FHR (3-15 beats) and fetal MCA-PSV were significantly higher during activity than resting, and MCA-RI was significantly lower during resting than activity (P<0.05). Also, MCA-RI and MCA-PSV had a significant relationship with FHR both during resting and activity (p <0.05). Therefore, increased FHR following activity significantly decreased MCA-RI (P<0.05) and significantly increased MCA-PSV (P<0.05). Increased FHR directly affects fetal MCA-PSV and MCA-RI parameters. This should be considered in detecting fetal distress and anemia.
Keywords: Fetal Heart Rate (FHR), Fetal middle cerebral artery, Peak Systolic Velocity (PSV), Resistance Index (RI), Ultrasonography