From the Guidelines
Fetal growth restriction (FGR) is associated with an increase in middle cerebral artery (MCA) peak systolic velocity (PSV) due to the brain-sparing effect.
Key Findings
- The brain-sparing effect in FGR leads to increased blood flow to the brain, resulting in increased MCA PSV 1.
- MCA PSV may be a better predictor of perinatal mortality in preterm intrauterine growth restriction (IUGR) than the pulsatility index (PI) 1.
- The cerebroplacental ratio, which includes MCA PI, has emerged as a predictor of adverse outcome among fetuses with FGR 1.
- Doppler assessment of the MCA is a valuable tool in the management of fetuses with FGR, particularly in assessing fetal well-being and determining the timing of delivery 1.
Clinical Implications
- Regular assessment of fetal biometry, amniotic fluid volume, and Doppler US, including MCA PSV, is essential in the management of pregnancies with FGR 1.
- The use of MCA PSV and other Doppler indices can help identify fetuses at risk of adverse outcome and inform decisions on timing of delivery 1.
- Further study is needed to confirm the predictive value of MCA PSV in preterm IUGR and to establish clear guidelines for its use in clinical practice 1.
From the Research
Effect of Fetal Growth Restriction on Middle Cerebral Artery Peak Systolic Velocity
- Fetal growth restriction (FGR) has been associated with changes in middle cerebral artery (MCA) peak systolic velocity (PSV) 2, 3, 4, 5.
- A study found that MCA PSV values were not significantly different between FGR and appropriately grown (AGA) neonates on day 1 and day 3, but both groups showed a significant increase in MCA PSV from day 1 to day 3 2.
- Another study found that the mechanism of high MCA PSV is different in anemic and non-anemic FGR fetuses, and suggested that the process of cerebral autoregulation is present in the preterm FGR fetus 3.
- MCA PSV has been proposed as a valuable parameter in the clinical assessment of FGR fetuses with abnormal umbilical artery Doppler 4.
- A study found that MCA PSV above the 95th percentile at the diagnosis and delivery time was seen at a significantly higher rate with adverse perinatal outcomes, and suggested that evaluating MCA PSV with Doppler can be a helpful diagnostic method for early diagnosis of restriction and hypoxic fetuses 5.
Factors Affecting MCA PSV in FGR Fetuses
- Fetal hemoglobin has been found to be related to MCA PSV in anemic fetuses, while Pco2 and Po2 have been found to be related to MCA PSV in FGR fetuses 3.
- A study found that the trends of the MCA pulsatility index (PI) and MCA PSV provide more clinical information than does one single measurement, and that a high MCA PSV predicts perinatal mortality better than does a low MCA PI 4.
Clinical Utility of MCA PSV in FGR
- MCA PSV has been found to be a useful parameter in predicting perinatal mortality and morbidity in FGR fetuses 4, 5.
- Evaluating MCA PSV with Doppler has been suggested as a helpful diagnostic method for early diagnosis of restriction and hypoxic fetuses, and may be used in clinics as a non-invasive method to predict neonatal prognosis 5.