[Training in fetal ultrasound biometry: Prospective assesment of Objective Structured Assessment of Ultrasound Skills...

Fetal biometry quality directly influences obstetrical care relevance. However, obstetrician proficiencies are heterogeneous in particular during initial training.

To assess the predictive value of OSAUS scale to identify operators with enough command to perform a valid estimation of fetal weight (EFW) (I). This study also assesses OSAUS intra-operator inter-exams variability (II) and pass/fail score relevancy (III).

Lecturers in Nancy University Hospital assessed trainees' proficiency for EWF systematically and prospectively through OSAUS scale. The trainee assessment was performed right after the one of the senior operator (reference EFW) on three consecutive patients during standard care ultrasounds. To ensure variability in proficiency within the sample, previous practice was taken into account during enrollment ("novices" and "intermediates" for<20 and 20 past exams, respectively). Correlation between mean OSAUS and validity of EFW (a valid EFW was defined by a difference with the reference EWF<0.8 Z-score) and variability between consecutive assessments were assessed.

The study population was constituted of 8 "novice" and 8 "intermediate" trainees. Association between OSAUS and EFW validity was significant (P<0.03) (I). Intra-operator inter-exams variability was majored in the "novice" group (coefficients of variation were 25% vs. 10% in "novice" and "intermediate" group respectively) (II). Within the sample, specificity and positive predictive value of a pass/fail score OSAUS>3.5 to predict EFW validity were 77% and 71%, respectively (III).

A 3.5 OSAUS pass/fail score could provide a relevant threshold to estimate operator proficiency in assessing fetal biometry in an autonomous and secure way.