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EP05.04: How to measure amniotic fluid index? Comparison of two methods (vertical to abdominal contour or floor)
Author(s) -
Park J.,
Kim H.,
Kim M.,
Cha H.,
Seong W.
Publication year - 2018
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1002/uog.19834
Subject(s) - medicine , sagittal plane , umbilicus (mollusc) , transverse plane , significant difference , amniotic fluid , abdominal wall , umbilical cord , abdomen , anatomy , fetus , pregnancy , obstetrics , genetics , biology
Objectives: The transabdominal probe (TP) is recommended to be positioned usually vertical to floor and parallel to maternal sagittal plane when measuring amniotic fluid index (AFI). However, many examiners report AFI measured in different ways. This study was performed to investigate the difference of AFI according to the positioning of TP. Methods: AFI was measured in 105 gravidas without fetal abnormalities from 20 to 40 weeks of gestation by four experienced examiners according to the technique proposed by Phelan et al. Maternal abdomen was divided into four quadrants using the umbilicus and linea nigra as landmarks. AFI was generated by the sum of these four values without umbilical cord or fetal parts. In each patient, AFI was measured by four different ways. Group 1: TP kept vertical to floor and parallel to maternal sagittal plane, Group 2: TP kept vertical to abdominal contour and parallel to maternal sagittal plane, Group 3: TP kept vertical to floor and parallel to maternal transverse plane, Group 4: TP kept vertical to abdominal contour and parallel to maternal transverse plane. Repeated Measures Analysis of Variance (RMANOVA) was used for statistical analysis. Results: Mean gestational age at measure of AFI was 30.1 ± 5.7 weeks. AFI was different among four groups (15.24 ± 3.74 versus 16.93 ± 4.75 versus 14.75 ± 3.77 versus 15.98 ± 4.62, p<0.001). Post hoc analysis showed the difference in AFI existed between group 1 and 2 (p<0.001), group 2 and 4 (p=0.003) and group 3 and 4 (p<0.001). There was no difference in AFI between group 1 and 3 (p=0.385). Conclusions: AFI was overestimated when TP was positioned vertical to abdominal contour compared to which acquired by positioning TP vertical to floor. We need to use different reference values according to the positioning of TP. When we kept TP vertical to abdominal contour to measure AFI, the direction of TP also influenced on determination of AFI. This was not the case in TP kept vertical to floor.