Lung ultrasound in pregnant women during the COVID-19 pandemic: an interobserver agreement study among obstetricians

PURPOSE To establish an interobserver agreement to perform lung ultrasound (LUS) on pregnant women by obstetricians with different levels of expertise, and to provide data by confirming our findings by an expert radiologist. METHODS This prospective study was conducted in a tertiary 'Coronavirus Pandemic Hospital' in April, 2020. Pregnant women suspected of COVID-19 were included. Two experienced obstetricians blindly performed LUS on pregnant women separately and noted their scores for 14-lung zones. Following a theoretical and hands-on practical course, one experienced obstetrician, two novice obstetric-residents and an experienced radiologist blindly evaluated anonymized and randomized still-images and videoclips retrospectively. Weighted Cohen's-kappa and Krippendorff's alpha tests were used to assess the interobserver agreement. RESULTS 52 pregnant women were included with confirmed diagnosis rate of 82.7% for COVID-19. A total of eligible 336 still-images and 115 videoclips were included in final analysis. Overall weighted Cohen's-Kappa values ranged between 0.706 and 0.912 for 14-anatomical landmarks. There were only 7 instances of major disagreement (>1 point) in the evaluation of pre-scored 14-anatomical zones of 52 patients (n=728). The overall agreement between radiologist and obstetricians for still images (Krippendorff's α = 0.856, 95% CI = 0.797 - 0.915) and videoclips (Krippendorff's α = 0.785, 95% CI = 0.709 - 0.861) were good. CONCLUSION The interobserver agreement between obstetricians with different levels of experience on still-images and videoclips of LUS was good. Performing LUS on pregnant women by obstetricians and interpretation of pre-performed LUS images can be considered consistent following a brief theoretical and practical course.