Reliability of measuring the abdominal aortic diameter in neonates

  • Dr Jean Du Plessis, Dept of Cardiology, Princess Margaret Hospital for Children, Perth, Western Australia, Australia
  • Prof Paul Norman, School of Surgery, University of Western Australia, Perth, Australia, Australia
  • Dr James Ramsay, Dept of Cardiology, Princess Margaret Hospital for Children, Perth, Western Australia, Australia
  • Dr Andy Gill, Dept. of Neonatology, King Edward Memorial Hospital, Perth, Western Australia, Australia
  • Prof Karen Simmer, University of Western Australia, Perth, Western Australia, Australia
  • Joan Sharpe, Dept. of Cardiology, Princess Margaret Hospital for Children, Perth, Western Australia, Australia
  • Elaine Pascoe, Clinical Research and Education, Princess Margaret Hospital for Children, Perth Western Australia, Australia

    • Background: Intra-uterine growth restriction influences aortic wall thickness and may predict cardiovascular disease. The possibility that adult aneurysmal arterial disease has fetal origins has attracted little attention. We explored the feasibility and repeatability of measuring infrarenal aortic diameter in neonates.
    Aim: 1) Determine reliability and repeatability of infrarenal aortic diameter measurements in neonates. 2) Determine whether Two-dimensional or M-mode measurements are superior.
    Method: Twenty-six neonates ranging from 25 to 41 (median=38.3) weeks had their infrarenal aorta scanned in coronal views obtained from either the left or right flanks. Two-dimensional and M-mode images were recorded and measured in both systole and diastole. Scans were re-measured at a later stage by a sonographer blinded to previous measurements. Inter-rater agreement was measured using an intra-class correlation coefficient (ICC) and intra-rater reliability with Pearson’s correlation coefficient (r).
    Results: Inter-rater agreements were high for M-mode images in both systole (ICC=0.78, 95% CI 0.58-0.90) and diastole (ICC=0.75, 95% CI 0.52-0.88) and very high for two-dimensional images in both systole (ICC=0.94, 95% CI 0.87-0.97) and diastole (ICC=0.93, 95% CI 0.85-0.97). Intra-rater reliability was high for M-mode images in systole (r=0.79, 95% CI 0.49-0.92) and diastole (r=0.83, 95% CI 0.56-0.94) and very high for two-dimensional images in systole (r=0.92, 95% CI 0.78-0.97) and diastole (r=0.91, 95% CI 0.77-0.97).
    Conclusion: This study describes a new technique to reliably and repeatibly measure the infrarenal aortic diameter in neonates. Two-dimensional measurements are superior to M-mode measurements and future studies measuring infra-renal aortic diameter in neonates should use two-dimensional measurements.