Curvilinear versus phased array transducer: using the obstetric ultrasound for focused cardiac ultrasound in laboring patients - a randomized controlled assessment

Background: Focused cardiac ultrasound is an effective tool for assessing obstetric patients, but access to phased array transducers is limited in many low-resource settings. This study aimed to determine if curvilinear transducers could produce clinically useful ultrasound images non-inferior to phased array transducers. Methods: Laboring patients were recruited for focused cardiac ultrasound performed by six anesthesiologists with limited echocardiography experience. Curvilinear and phased array transducers were used to obtain standard views. The first transducer used was randomly assigned. Blinded experts graded the images on a scale of 1 to 5, with grades ≥ 3 sufficient for clinical decisions. The primary outcome was the percentage of patients with sufficient images (grade ≥ 3) in at least two views using curvilinear versus phased array transducers. Secondary outcomes included the clinical utility of individual views and a non-inferiority comparison of transducers. Results: Seventy parturients were scanned. Clinically useful examinations were achieved in 91.4% (95% CI 82.3%, 96.8%) of patients with curvilinear transducers compared to 95.7% (95% CI 88.0%, 99.1%) with phased array transducers. Using a noninferiority margin of 15%, curvilinear transducers were noninferior for clinical decisions (−4.3% 90% CI: −11.9%, −3.3%) largely due to parasternal views. Subcostal and apical views were individually inconclusive and IVC views were inferior. Measures of cardiac dimensions and systolic function were deemed measurable with less frequency on curvilinear images but concordant when measured. Conclusions: Anesthesiologists can effectively use curvilinear transducers for focused cardiac ultrasound in obstetric patients, although phased array transducers may be superior for measuring cardiac dimensions and function. © 2025 Elsevier Ltd