Is There a Difference in Sonographic Estimation of Amniotic Fluid Volume When Measuring With the Probe Perpendicular to the Floor Compared With Perpendicular to the Uterine Contour?

Objective: This study sought to determine whether there is a significant difference in amniotic fluid measurements when measuring perpendicular to the floor compared with perpendicular to the uterine contour using both amniotic fluid index and single deepest pocket.

Methods: This was a single-centre, prospective study of women with singleton gestation who were undergoing fetal ultrasound examination. A total of 240 women were enrolled, and single deepest pocket and amniotic fluid index were measured with both techniques. Correlation coefficient and intraclass correlation coefficient were used to assess the agreement between the values using the two methods of measurement (Canadian Task Force Classification II-2).

Results: A strong correlation was found between amniotic fluid index measurements (correlation coefficient 0.82; intraclass correlation coefficient 0.7). A strong correlation also was found between single deepest pocket measurements (correlation coefficient 0.7; intraclass correlation coefficient 0.6).

Conclusion: The measurement of amniotic fluid index and single deepest pocket can be performed either perpendicular to the floor or perpendicular to the uterine contour. There is no significant difference between these measurements and they correlate well.