Doppler Ultrasound Reproducibility Varies in Pregnancy

DOPPLER ultrasound reproducibility varied across commonly used Doppler measurements used in pregnancy, with a systematic review finding generally poor-to-moderate reproducibility under strict True Reproducibility of Ultrasound Techniques (TRUST) criteria.

The review assessed whether umbilical artery (UA), fetal middle cerebral artery (MCA) and uterine artery (UtA) Doppler measurements produced consistent results between observers.

Doppler ultrasound is widely used to assess placental function and fetal wellbeing, particularly in high-risk pregnancies, by measuring blood-flow patterns that can indicate fetal compromise.

Different Doppler Measures Showed Different Reliability

Researchers screened 2,426 records and included 26 studies involving 2,457 patients. Eight studies assessed UA Doppler, 11 examined MCA Doppler and 11 evaluated UtA Doppler, while two reported cerebroplacental ratio measurements.

For UA pulsatility index (PI), the pooled intraobserver intraclass correlation coefficient (ICC) was 0.88, compared with 0.68 between observers. MCA-PI showed pooled ICCs of 0.85 within observers and 0.80 between observers. For mean UtA-PI, the corresponding values were 0.90 and 0.84.

The findings indicated that measurement consistency could vary depending on the Doppler parameter and whether the same or different observers performed the assessment. The researchers also noted that maternal BMI, fetal position, fetal movement, amniotic fluid volume, placental position, operator experience and technical factors could all contribute to variability.

Standardisation Could Strengthen Fetal Assessment

The review’s interpretation was limited by substantial differences between studies, including gestational age, equipment, measurement protocols and observer experience. Incomplete reporting of variability estimates and confidence intervals also prevented some analyses.

The researchers highlighted opportunities to improve Doppler ultrasound reproducibility through standardised probe placement, angle correction and sample-gate size, alongside regular operator training and certification. Multiple measurements per session, averaging bilateral UtA-PI results and quality audits when outliers were identified were also suggested.

Automated Doppler software with error-checking and artificial intelligence-based image analysis could potentially reduce operator variability, although these technologies require rigorous evaluation. Large multicentre studies using strict measurement protocols were needed to establish how best to improve reproducibility and whether this could affect clinical outcomes.

The researchers also noted that Doppler abnormalities were not pathognomonic for adverse outcomes and were interpreted alongside maternal history, fetal biometry and additional fetomaternal monitoring.

Reference

Prins LI et al. Interobserver and intraobserver variability of fetal and maternal Doppler measurements: systematic review and meta-analysis. Ultrasound Obstet Gynecol. 2026;DOI:10.1002/uog.70287.

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