Intra- and inter-observer reproducibility study of gestational age estimation using three common foetal biometric parameters: Experienced versus inexperienced sonographer

AimTo assess reproducibility of estimating gestational age (GA) of foetus using femur length (FL), biparietal diameter (BPD) and abdominal circumference (AC) within experienced and inexperienced sonographers and between the two.Patients and methodsTwo sets of GA estimates each were obtained for FL, BPD and AC by the two observers in 20 normal singleton foetuses. The first estimates for the three biometric parameters were made by the experienced sonographer. Subsequently, the inexperienced sonographer, blind to the estimates of the first observer obtained his own estimates for the same biometric parameters. After a time interval of ten minutes the process was repeated for the second set of GA estimates. All the gestational age estimates were made following standard protocol. Statistical analysis was performed by Pearson's and intraclass correlations, coefficient of variation and Bland–Altman plots. Statistical inferences were drawn at p < 0.05.ResultsThe Pearson's and intraclass correlations of between GA estimates within and between both observers from measurement of FL, BPD and AC were very high and statistically significant (p < 0.05). Coefficient of variation for duplicate measurements for GA estimates within observers and between observers were quite negligible. Between observers, the first and second GA estimates from FL measurements showed the least variation. Estimates from BPD and AC measurements showed greater degree of variation between the observers.ConclusionReproducibility of GA estimation using FL, BPD and AC within experienced and inexperienced sonographers and between the two was excellent. Therefore, a fresh Nigerian radiography graduate with adequate exposure in obstetric ultrasound can correctly determine the gestational age of foetus in routine obstetric ultrasound without supervision.