Velocity Time Integral: A Novel Method for Assessing Fetal Anemia.

Area of Science:

• Perinatology
• Fetal Medicine
• Diagnostic Ultrasound

Background:

• Maternal alloimmunization poses risks to fetal well-being.
• Doppler ultrasound is crucial for assessing fetal circulation.
• Middle cerebral artery (MCA) peak systolic velocity (PSV) is a key indicator of fetal anemia.

Purpose of the Study:

• To evaluate the velocity time integral (VTI) in the MCA of fetuses with and without suspected anemia due to maternal alloimmunization.
• To determine if MCA VTI can serve as an additional marker for fetal anemia.

Main Methods:

• Retrospective analysis of 255 fetal Doppler ultrasound examinations from 16-40 weeks gestation.
• Measurement of MCA VTI, systolic deceleration-diastolic time, systolic acceleration time, and PSV.
• Comparison of VTI in fetuses with MCA-PSV ≥ 1.5 MoM (suspected anemia) versus MCA-PSV < 1.5 MoM (normal).

Main Results:

• MCA VTI demonstrated a significant increase throughout gestation (p = 0.003).
• Fetuses with suspected anemia (MCA-PSV ≥ 1.5 MoM) exhibited significantly higher VTI compared to those without (14.1 cm vs. 9.1 cm, p < 0.001).
• VTI/s was also significantly higher in fetuses with suspected anemia (33.75 cm/s vs. 22.04 cm/s, p < 0.001).

Conclusions:

• MCA VTI significantly increases in fetuses with suspected anemia, suggesting increased cerebral blood flow.
• Elevated MCA VTI may indicate higher perfusion of hemodiluted blood to the brain in anemic fetuses.
• MCA VTI is a feasible measurement and a potential novel marker for the development of fetal anemia.