Informed decision-making about the fetal anomaly scan: what knowledge is relevant?

This study had two objectives. The first was to determine the contents of relevant knowledge needed for informed decision-making (IDM) in second-trimester ultrasound screening for fetal anomalies, with the goal of developing a knowledge measure for use in large-scale program evaluations. The second was to compare the contents of decision-relevant knowledge for second-trimester ultrasound screening with those for first-trimester screening for Down syndrome using the combined test.

A generic list of content domains for knowledge about screening was extracted from the literature. Items reflecting specific knowledge domains for second-trimester ultrasound screening were constructed. An expert group of professionals and pregnant women expressed whether domains and items represented decision-relevant knowledge.

Regarding second-trimester ultrasound screening, the experts scored all knowledge domains as (very) important. The meaning of an abnormal test result, the disorders being screened for, and the purpose of the screening were rated as very important for IDM, along with the voluntary nature of the test. All knowledge domains were included in the final measure. Importance ratings of knowledge domains for first-trimester Down syndrome screening and for second-trimester ultrasound screening were highly correlated (Pearson's r = 0.71). The domain 'consequences of a positive test result' was considered more important in first-trimester Down syndrome screening than in second-trimester ultrasound screening.

We have developed a knowledge measure for second-trimester ultrasound screening for fetal anomalies for use in routine, large-scale program evaluations.