Amniotic fluid as a vital sign for fetal wellbeing

Abstract

Introduction: Amniotic fluid, once thought to merely provide protection and room for necessary movement and growth for the fetus, is now understood to be a highly complex and dynamic system that is studied as a data point to interpret fetal wellbeing. Methods: Assessment of amniotic fluid volume is now routine when performing a sonographic evaluation of fetal status and is an important consideration in the assessment and management of perinatal morbidity and mortality.^1,2 In this review, we will cover the dynamics that affect amniotic fluid volume, review methods for measurement and quantification of volume, review definitions for normative data as related to neonatal outcomes, and provide evidence based guidance on the workup and management options for oligoydramnios and polyhydramnios in singleton and twin pregnancies. Conclusions: When abnormalities of fluid exist, appropriate workup to uncover the underlying etiology should be initiated as adverse fetal outcomes are sometimes associated with these variations from normalcy.

Keywords: amniotic fluid volume; oligohydramnios; polyhydramnios.

Figure 1

From Magann, et al. ² . Comparison of normal amniotic fluid volumes (dye determined or directly measured) across gestation: Brace and Wolf ⁴¹ Magann, et al ⁴² and Queenan et al ²⁶ .