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. 2008 Oct 15:5:5.
doi: 10.1186/1742-4755-5-5.

Inter- and intra-observer variability in Sonographic measurements of the cross-sectional diameters and area of the umbilical cord and its vessels during pregnancy

Cristiane Barbieri  1 , Jose G Cecatti, Carla E Souza, Emilio F Marussi, Jose V Costa
Affiliations

Inter- and intra-observer variability in Sonographic measurements of the cross-sectional diameters and area of the umbilical cord and its vessels during pregnancy

Cristiane Barbieri et al. Reprod Health. .

Abstract

Background: The purpose of the study was to evaluate inter- and intra-observer variability in sonographic measurements of the cross-sectional area of the umbilical cord and the diameters of its vessels in low-risk pregnancies of 12 to 40 weeks of gestation.

Methods: A prospective cross sectional study was performed in 221 pregnant women at different gestational ages. Measurements were carried out also by a second observer to evaluate inter-observer variability and repeated once again by the first observer to assess intra-observer variability. The linear correlation between the measurements (Spearman's coefficient of correlation) and their reliability through the intraclass correlation coefficient (ICC), the Cronbach's alpha coefficient and the limits of agreement proposed by Bland and Altman were evaluated.

Results: The results showed that inter-observer and intra-observer variability did not show any significant difference between examiners. A good linear correlation between the measurements and reliability was obtained, with values of R, ICC and Cronbach's alpha all above the standard limits.

Conclusion: It is possible to conclude that inter- and intra-observer variability in the measurements of the umbilical cord and its vessels was small; their reliability and agreement were good.

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Figures

Figure 1
Figure 1
Ultrasonographic measurement A. of the cross-sectional area of the umbilical cord (C), the diameter of the umbilical vein (V) and the umbilical artery (A); and B. of the longitudinal section of the umbilical cord (between 12 and 14 weeks).
Figure 2
Figure 2
Inter-observer agreement by plotting the mean differences against the mean values (method of Bland & Altman) for the following measurements: A. Diameter of the umbilical cord (cord1 and cord2 are respectively the measurements of observer 1 and 2); and B. diameter of the area of the umbilical cord (area1 and area2 are respectively the measurements of observer 1 and 2).
Figure 3
Figure 3
Linear correlation (r = correlation coefficient of Spearman) of the inter-observer ultra-sonographic measurements: A. of the diameter of the umbilical cord (cord1 and cord2 are respectively the measurements of observer 1 and 2); and B. of the cross-sectional area of the umbilical cord (area1 and area2 are respectively the measurements of observer 1 and 2).
Figure 4
Figure 4
Linear correlation (r = correlation coefficient of Spearman) of the intra-observer ultrasonographic measurements: A. of the diameter of the umbilical cord (cord1 and cord3 are respectively the first and second measurements of observer 1); and B. of the cross-sectional area of the umbilical cord (area1 and area3 are respectively the first and second measurements of observer 1).
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