The influence of maternal body mass index on interobserver variability of fetal ultrasound biometry and amniotic fluid assessment in late pregnancy.
Martins JG., Kawakita T., Gurganus M., Baraki D., Jain P., Papageorghiou AT., Abuhamad AZ.
OBJECTIVES: Determine interobserver reproducibility of fetal ultrasound biometry and amniotic fluid assessment in the third trimester according to BMI categories. METHODS: Prospective cohort of women with singleton gestations beyond 34 weeks, recruited into 4 groups according to BMI categories: normal, overweight, obese and morbid obese. Multiple pregnancies, diabetes, growth and fetal abnormalities were excluded. Biometric and fluid measurements were obtained by two experienced physicians/sonographers, blinded for gestational age and each other's measurements. Differences between observers were expressed as gestational age-specific Z-scores. Interobserver correlation coefficient (ICC) and Cronbach's reliability coefficient (CRC) were calculated. Bland-Altman plots were constructed to assess the level of reproducibility. RESULTS: 110 women were prospectively enrolled (1,320 measurements obtained by 17 sonographers / physicians): 20 had normal BMI (18.2%), 30 were overweight (27.3%), 30 were obese (27.3%) and 30 were morbidly obese (27.3%). Except for MVP (CRC 0.66), all biometric parameters and AFI had high level of reproducibility (CRC 0.84 - 0.93). Among BMI groups: BPD had the highest level of reproducibility (CRC > 0.90); AC and FL reproducibility increased with increasing BMI while MVP decreased. Interobserver differences for biometry fell within the 95% limits of agreement. CONCLUSIONS: Obesity does not seem to negatively impact the reproducibility of fetal biometric parameters when undertaken by experienced physicians/sonographers. This article is protected by copyright. All rights reserved.