Intra- and interobserver variability in ultrasound measurements of abdominal aortic diameter. The Tromsø study

Objectives:To assess the variability of ultrasonographic measurements at different levels of the abdominal aorta.Design:Reproducibility study as part of a population health screening for abdominal aortic aneurysm.Materials and methods:In 1994/1995 a total of 6892 subjects underwent ultrasound examination of the abdominal aorta. Variability of measurements was assessed in the beginning and end of the survey period by inviting 112 randomly selected participants to a second ultrasound scan within 3 weeks of the first scan. The subjects were examined by an experienced radiologist and three sonographers who had been given a short course in ultrasonography. All examiners were blinded to each other's results.Results:Variability was similar in the beginning and end of the survey period. Both the intra- and interobserver variability were less than 4 mm for all sonographers in measurements of maximal infrarenal aortic diameter, and variability was similar for measurements in the anterior-posterior and transverse plane. Variability was greater for measurements at the renal level than aortic bifurcation level. The radiologist had lower variability than the other sonographers.Conclusion:Ultrasound measurements of the maximal diameter can be obtained with a high degree of accuracy. Inexperienced sonographers may achieve acceptable performance given appropriate training and surveillance