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Continuous wave Doppler flow velocity waveforms from the umbilical artery in normal pregnancy
P Fogarty1, B Beattie, A Harper
1Department of Obstetrics and Gynaecology, Royal Maternity Hospital, Belfast, N. Ireland.
Journal of Perinatal Medicine
|January 1, 1990
Summary
This study establishes normal reference ranges for umbilical artery Doppler ultrasound indices in 85 pregnancies. Findings provide crucial data for identifying abnormal pregnancy through fetal Doppler assessment.
Area of Science:
- Obstetrics and Gynecology
- Fetal Medicine
- Diagnostic Ultrasound
Background:
- Umbilical artery Doppler ultrasound is vital for assessing fetal well-being.
- Establishing accurate normal reference ranges is essential for interpreting Doppler indices.
Purpose of the Study:
- To establish normal reference ranges for Pulsatility Index (P.I.), Resistance Index (R.I.), and A/B ratio in umbilical artery waveforms.
- To provide a comprehensive dataset for uncomplicated singleton pregnancies.
Main Methods:
- Prospective longitudinal study of 85 singleton pregnancies (16-40 weeks gestation).
- Continuous wave Doppler ultrasound used to measure P.I., R.I., and A/B ratio.
- Non-parametric statistics used due to positively skewed frequency distributions.
Main Results:
- Established normal reference ranges for umbilical artery Doppler indices.
- Demonstrated a decrease in placental resistance as term approaches (e.g., 50% PI at 16 weeks: 2.06; at 40 weeks: 0.85).
- Largest published study of its kind using continuous wave Doppler.
Conclusions:
- Provides a comprehensive reference of normal umbilical artery Doppler values.
- Offers a sound basis for the further study of abnormal pregnancy.
- Highlights the importance of non-parametric statistics for Doppler index analysis.