Doppler Indices
Numerical parameters calculated from Doppler waveform analysis to assess vascular resistance and blood flow patterns.
Full Definition
Doppler indices are standardized measurements derived from Doppler ultrasound waveform analysis that quantify vascular resistance and flow characteristics. The three primary indices used in fetal medicine are the pulsatility index (PI), resistance index (RI), and systolic/diastolic ratio (S/D ratio). These measurements are angle-independent and provide objective assessment of placental and fetal circulation. Normal reference ranges exist for different gestational ages and vessels, allowing identification of pathological conditions such as placental insufficiency or fetal growth restriction through abnormal index values.
Usage
Usage note: Always capitalize 'Doppler' and use plural form for multiple measurements.
In Context
- "Doppler indices were elevated in the umbilical artery, suggesting increased placental resistance." — Fetal surveillance report
- "Normal Doppler indices in the middle cerebral artery indicated adequate fetal oxygenation." — High-risk pregnancy monitoring