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Interobserver variability of midtrimester fetal nuchal thickness
A Borrell1, D Costa, R D Delgado
1Department of Obstetrics and Gynecology, University of Barcelona Medical School, Catalonia, Spain.
Summary
Interobserver variability in fetal nuchal thickness (NT) ultrasound measurements was assessed. Experienced ultrasonographists demonstrated acceptable agreement, crucial for Down
Area of Science:
- Prenatal diagnosis and obstetric ultrasound.
- Fetal medicine and genetic screening.
Background:
- Nuchal thickness (NT) measurement is a key first-trimester screening parameter for fetal aneuploidies.
- Standardization of NT measurement is essential for accurate risk assessment.
Purpose of the Study:
- To evaluate the interobserver variability of fetal nuchal thickness (NT) measurements.
- To determine the reliability of NT measurements among ultrasonographists with varying expertise levels.
Main Methods:
- NT was measured in 103 early midtrimester pregnancies (13-18 weeks) by three ultrasonographists.
- Measurements were performed blindly, and Lin's concordance correlation coefficient and Kappa statistics were used.
- Concordance was assessed between observers with different experience levels.
Main Results:
- Mean differences between observer pairs ranged from 0.44 to 0.57 mm.
- Higher concordance correlation was observed between more experienced ultrasonographists (r = 0.77 vs. r = 0.51).
- Agreement for identifying cases with NT ≥ 5 mm (risk for Down's syndrome) was high (98% agreement; kappa = 0.90).
Conclusions:
- Interobserver variability in fetal NT measurements is acceptable among experienced ultrasonographists.
- The expertise of the ultrasonographist significantly impacts the concordance of NT measurements.
- Standardized training may further improve consistency in NT assessments.