Measurement of amniotic fluid volume

Abstract

The qualitative or semi-quantitative assessment of amniotic fluid volume (AFV) is a standard component of every ultrasound in the second and third trimesters of pregnancy. AFV abnormalities are associated with various pregnancy complications. In clinical practice, ultrasound (US) assessment of AFV is used in conjunction with other clinical and sonographic parameters (biophysical profile, non-stress test, estimated fetal weight on ultrasound, clinical examination) to make effective medical decisions to maintain fetal well-being in the management of pregnancies with obstetric complications. US is the most common AFV assessment technique, in which AFV is determined on a basis of the opinion of a physician (qualitatively) or on a basis of the value of the maximum vertical pocket (MVP) and amniotic fluid index. These techniques are well suited for detecting fetuses with normal AFV; however, they have insufficient accuracy for diagnosing oligohydramnios and polyhydramnios. Furthermore, ultrasound AFV assessment in twins poorly corresponds with the reference values for oligohydramnios and polyhydramnios. Despite this, it is advisable to use qualitative and semi-quantitative (MVP) methods for AFV assessment. Results for each twin are interpreted using the same MVP criteria as those for single fetuses.