Longitudinal z Score Distribution in Sonographic Fetal Biometry: Influence of Examiner and Experience

[Skills assessment for the practice of fetal ultrasound biometry: Prospective validation of the OSAUS METHOD score]

OBJECTIVES

To develop and validate a customized variant for fetal biometry of the generic OSAUS score (Objective Structured Assessment of Ultrasound Skills) METHODS: The 5-points OSAUS METHOD grid was elaborated by defining five target skills specific to fetal biometry for each thematic item of the generic score. The level of skills of 43 trainees was prospectively assessed during an ultrasound examination by using this grid. The results of the "novice" level group (experience<10 ultrasounds) were compared to those of the "intermediate" level group (experience≥10 ultrasounds) (I). The reached/non-reached skills ratio within the different items composing the score allowed the identification of priority areas of improvement (II). Previously published distribution and actual distribution of ratings according to the generic pass/fail score were compared (III).

RESULTS

Median scores of "novices" (n=29) and "intermediates" (n=14) groups were statistically different, 1.87 (±0.75) and 3.31 (±0.83) (P=1.85-5), respectively and corresponded to the pre-existing experience (I). A lower ratio of reached skill allowed the identification of "documentation of the examination" item as a priority area of improvement for both groups (II). The relevance of the pass/fail score is consolidated, even if an overlap was observed between novices and intermediates groups (III).

CONCLUSIONS

The relevancy and feasibility of using OSAUS scoring method for fetal biometry are supported. In addition, the possibility of comparisons with generic OSAUS remains.

Accuracy of sonographic fetal weight estimation in full-term singleton pregnant women

OBJECTIVES

To investigate the factors which might influence the sonographic fetal weight estimation (SFWE) accuracy.

METHODS

This prospective study was conducted among 949 singleton term pregnant women who delivered at a tertiary center, from January 2017 to December 2017. All participants' maternal (i.e. parity, age, body mass index and gestational weight gain during pregnancy), fetal sonographic (i.e. fetal presentation, amniotic fluid index, localization of placenta and estimated fetal weight) and neonatal (birth weight and gender) characteristics were recorded. A p<0.05 was considered significant.

RESULTS

The mean absolute percent error (APE) values of SFWE was 8.2±6.5 percent, and overall failure ratio (APE >10%) was 33%. In failure group, primiparous woman and cephalic presentation fetus were significantly more common compared to accuracy group (55.9% vs.44.8%; p=0.001 and 98% vs. 95.2%; p=0.03, respectively). In contrast, the mean neonatal birth weight (NBW) value was significantly lower in failure group compared to success group (3250±565 gr vs. 3404±410 gr; p=0.001). The correlation between SFWE and NBW was linear, however negative, and significant (p=0.001). Logistic regression analysis revealed that primiparous woman, cephalic presentation fetus and <3300 gr NBW were independent risk factors for the SFWE failure (relative risks were 1.6, 2.8 and 2.4 respectively, p<0.05).

CONCLUSION

SFWE has a high correlation with NBW, however it's accuracy is still unsatisfactory, and depend on many unpredictable and inconsistent factors.