Amniotic fluid index (AFI) Archives - Revista Brasileira de Ginecologia e Obstetrícia

Purpose: to compare the capacity of diagnosing oligohy-dramnios by ultrasound using different measures of the maximum pool depth of amniotic fluid in comparison to the amniotic fluid index among normal pregnant women from the 36th to the 42nd week of gestation. Methods: a descriptive study of diagnostic validity was perfomed, on 875 normal pregnant women who were studied through routine obstetric ultrasound examinations, including the measure of the maximum pool depth for the diagnosis of oligohydramnios, using the amniotic fluid index as the gold standard. The data were analyzed through sensitivity and specificity of the maximum pool depth of amniotic fluid using 10, 20 and 30 mm cut-offs, in comparison to the amniotic fluid index values of the normal curve in percentiles 2.5 and 10 for different gestational ages. Results: the maximum pool depth had a poor sensitivity to diagnose oligohydramnios when 10 and 20 mm were used as cut-offs, and good sensitivity and specificity when 30 mm was used, in comparison to the amniotic fluid values in percentiles 2.5 and 10. The best sensitivity and specificity of the maximum pool depth were when found using a 30 mm cut-off in comparison to 2.5 percentile to diagnose oligohydramnios. Conclusions: the capacity to diagnose oligohydramnios by the measure of the maximum pool depth is satisfactory only with the cut-off of 30 mm