To guide or not to guide: A randomized study on the use of needle guide for chorionic villus sampling training

Chorionic villus sampling (CVS) is an invasive prenatal diagnostic procedure used to detect fetal genetic anomalies. CVS is increasingly replaced by noninvasive prenatal testing (NIPT). As a consequence, maintaining procedural skills among trainees has become challenging. Despite this, optimal training methods for CVS remain uncertain, particularly regarding whether techniques involving context variation, needle guides, or freehand approaches yield superior skill acquisition and performance. This randomized controlled study aimed to evaluate these training strategies, specifically focusing on skill transfer among novices in ultrasound-guided CVS.

In this randomized controlled trial, 101 ultrasound novices were allocated into three training groups: context variation, needle-guided, and freehand techniques. Participants completed a 1-h training session performing ultrasound-guided needle punctures on ballistic gel models. The context variation group alternated between needle-guided and freehand techniques with varying visual constraints. After training, each participant completed four CVS transfer tests using a CVS simulator manikin, involving two needle-guided and two freehand procedures, with differing placental positions. Blinded expert raters evaluated participant performance using a scoring system with established validity evidence. Statistical analyses included linear mixed-effect models, ANOVA, and Pearson correlation coefficients.

There were no significant differences in overall performance scores among the three training groups (F[2, 92.0] = 0.06, p = 0.94). However, performance significantly improved during transfer tests when participants used a needle guide, irrespective of their initial training method (F[1, 266.0] = 49.5, p < 0.001). Specifically, using a needle guide significantly enhanced scores for pre-puncture ultrasound assessment (t[370] = -4.1, p < 0.001), insertion site selection (t[370] = -3.8, p < 0.001), sampling technique (t[370] = -5.8, p < 0.001), and overall procedural performance (t[370] = -5.8, p < 0.001).

Training approaches, including needle-guided, freehand, and context variation techniques, did not differ significantly in their effect on learning ultrasound-guided CVS. However, the consistent improvement in procedural performance with needle-guided techniques suggests that incorporating needle guides into CVS training could promote safer practice for novice learners, particularly as clinical training opportunities become increasingly scarce.