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Doppler ultrasound measurements show moderate to high intraobserver reliability but lower interobserver consistencyUltrasound Measurements Show Variable Results in Pregnancy Monitoring

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Key Takeaway
Note that interobserver reliability for Doppler ultrasound measurements is lower than intraobserver reliability.

This meta-analysis evaluates the intra- and interobserver reliability of umbilical artery (UA), fetal middle cerebral artery (MCA), and uterine artery (UtA) Doppler ultrasound measurements across 2457 measurements. The analysis focuses on the consistency of these measurements as critical components in monitoring fetal and maternal health during pregnancy.

The findings indicate high intraobserver ICC values for all parameters: 0.88 for UA-PI, 0.85 for MCA-PI, and 0.90 for UtA-PI. However, interobserver ICC values were lower, reported as 0.68 for UA-PI, 0.80 for MCA-PI, and 0.84 for UtA-PI. These results suggest that while individual operators may achieve high consistency, variability increases when different observers perform the measurements.

Despite the high intraobserver scores, the authors note that reproducibility is considered poor-to-moderate when measured against strict TRUST criteria. This highlights a significant gap in consistency across different practitioners. The authors suggest that these findings underscore the necessity for standardized ultrasound measurement protocols, advanced technologies such as AI-supported applications, and specialized training programs to improve the reliability of fetal assessments in clinical practice.

A large meta-analysis looked at the reliability of Doppler ultrasound measurements during pregnancy. These measurements, which include the umbilical artery, middle cerebral artery, and uterine artery, are used to monitor the health of both the mother and the baby. The study included data from 2,457 cases to see how consistent these readings were when taken by the same person or different people.

The results showed that while measurements were generally consistent when taken by the same person, there was more variation when different people performed the same test. Specifically, the umbilical artery showed a correlation of 0.88 for the same observer but only 0.68 for different observers. The uterine artery and middle cerebral artery showed slightly higher consistency across different observers, but still showed some variation.

Because of these differences, the study suggests that standardizing how these tests are performed is very important. Because some measurements did not meet strict reproducibility standards, experts recommend using better training programs and advanced technology to ensure the most accurate results for patients.

What this means for you:
Ultrasound measurements can vary between different observers, highlighting the need for standardized testing protocols.

Common questions

How consistent are ultrasound measurements between different doctors?

The study found that measurements can vary when performed by different people. For example, the umbilical artery pulsatility index showed a correlation of 0.88 when measured by the same person, but dropped to 0.68 when measured by different observers. This suggests that different technicians or doctors may get different results for the same test.

What specific parts of the ultrasound were measured?

The study looked at three specific areas: the umbilical artery (UA), the fetal middle cerebral artery (MCA), and the uterine artery (UtA). These are used to monitor blood flow and health during pregnancy. The results showed that the uterine artery had a correlation of 0.84 when measured by different observers.

Why is there a difference in measurement reliability?

The study noted that some measurements showed poor to moderate reproducibility under strict criteria. Because of this, the researchers suggest that using standardized protocols, better training programs, and advanced technologies like AI-supported applications can help make these measurements more reliable for everyone.

Study Details

Study typeMeta analysis
Sample sizen = 2,457
EvidenceLevel 1
PublishedSep 2026
View Original Abstract ↓
OBJECTIVES: To evaluate the variability and reproducibility of umbilical artery (UA), fetal middle cerebral artery (MCA) and uterine artery (UtA) Doppler ultrasound measurements in pregnancy. METHODS: A systematic search of MEDLINE, EMBASE and the Cochrane Library (CENTRAL) was conducted from inception to 17 June 2024. Studies were included if they reported intra- or interobserver variability of UA, MCA or UtA Doppler ultrasound measurements in singleton or multiple pregnancies, using the intraclass correlation coefficient (ICC), concordance correlation coefficient, Cohen's kappa or limits of agreement. Data extraction was performed using standardized data-extraction forms. A meta-analysis was conducted using a random-effects model to account for heterogeneity, and variability estimates were pooled using Fisher's Z-transformation. Reproducibility was categorized according to the True Reproducibility of Ultrasound Techniques (TRUST) criteria. RESULTS: In total, 2426 records were screened. Of these, 26 studies including 2457 patients met the inclusion criteria; eight studies described UA Doppler, 11 described MCA Doppler and 11 described UtA Doppler results; two of the studies described cerebroplacental ratio results. The pooled intraobserver ICC for UA pulsatility index (PI) was 0.88 (95% CI, 0.77-0.94) and the pooled interobserver ICC was 0.68 (95% CI, 0.55-0.79). For MCA-PI, these values were 0.85 (95% CI, 0.69-0.93) and 0.80 (95% CI, 0.62-0.90), respectively, and for mean UtA-PI they were 0.90 (95% CI, 0.85-0.93) and 0.84 (95% CI, 0.78-0.89), respectively. Findings across studies suggested generally poor-to-moderate reproducibility according to the strict TRUST criteria. CONCLUSIONS: Our results emphasize that there is room for improvement regarding the reproducibility of Doppler ultrasound in routine obstetric practice. By standardizing ultrasound measurement protocols, advancing technologies such as artificial-intelligence-supported measurement applications and training programs, as well as obtaining multiple measurements per session and performing quality audits when outliers are detected, the field could move towards more accurate and reliable fetal assessments. © 2026 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.
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