Vaginal fluid index – The fifth amniotic pocket

Abstract

Normal amniotic fluid volume, with a normal biophysical profile, reassures fetal well-being. 1 Abnormal volumes, oligohydramnios, and polyhydramnios have been considered markers of pregnancies at risk of adverse outcomes. 2 Transabdominal ultrasound is used to quantitatively assess amniotic fluid volume, most commonly based on either the amniotic fluid index (AFI) or the single maximal vertical pocket (MVP) technique and gestational-specific nomograms are available. 3 The value of the AFI has been questioned in several studies, which showed that an abnormal test, low or high, is neither highly accurate nor predictive of an adverse outcome, whereas many pregnancies with a normal AFI will be falsely characterized as abnormal and a large number with a truly abnormal AFI will be missed. [4][5][6] The MVP measurement may be preferred over the AFI. A 2008 systematic review of randomized trials found that the use of the AFI increased the rate of diagnosis of oligohydramnios, induction of labor, and cesarean delivery due to fetal distress. 7