The Need for Device-Specific Training Before Handheld Ultrasound Use: Agreement and Repeatability of Simulated Aortic Aneurysm Diameter Measurements by Senior Sonography Students on a Familiar Conventional and an Unfamiliar Handheld System

Background: Ultrasound measurement of abdominal aortic aneurysm (AAA) diameter guides screening and surveillance, but whether students’ measurement competence on a conventional system transfers to an unfamiliar handheld device has rarely been assessed. Methods: Twenty-seven senior sonography students made three anteroposterior outer-to-outer measurements of two water-filled balloons embedded in gelatin (reference diameters 3.53 and 5.88 cm, calculated from the circumference before embedding), first on the familiar cart-based conventional system and then, in a fixed, non-randomised order, on a handheld system with which they had no prior hands-on experience. The primary outcomes were bias against the calculated reference, with equivalence testing (±5%), and the paired between-system difference, with Bland–Altman analysis; repeatability was assessed with repeatability coefficients. Results: Conventional measurements were equivalent to the calculated reference within ±5% (bias −0.09 cm, 95% CI −0.16 to −0.02; +0.07 cm, 95% CI −0.05 to +0.19). Handheld measurements were higher (+0.17 and +0.33 cm; both p < 0.001) and failed equivalence; the mean between-system difference was +0.26 cm (95% CI 0.18–0.34), without proportional bias. Single-reading repeatability coefficients were 0.31–0.67 cm. Conclusions: Students’ conventional-system measurements agreed closely with the calculated reference, although this reference was not verified after embedding. Because device type was confounded with operator inexperience and with a fixed testing order, which introduces an unquantifiable learning or fatigue effect, the 0.26 cm value is an observed between-system difference under the study conditions and cannot be attributed to the handheld device itself. Measurement competence did not transfer automatically to a new device, underlining the critical need for device-specific training before handheld systems are used for aortic measurement. These implications are educational and technical; phantom findings do not support clinical surveillance recommendations without confirmation in patients.