Oligohydramnios - Incidence and perinatal outcome - Review.

Oligohydramnios is the condition in which the liquor amni is reduced in amount to the extent of less than 200 ml at term. Sonographically, it is defined as when the maximum vertical pocket of liquor is < 2 cm or when amniotic fluid index is less than 5cm (<10^th percentile). Oligohydramnios can be defined by an amniotic fluid index less than 5^th percentile for gestational age or an amniotic fluid index <5.0 cm regardless of gestational age. Amniotic fluid volume decreases progressively during the last few weeks of pregnancy and during the postdate period, it is estimated that there is a 93 percent decline in amniotic fluid each week. The normal decline in the amniotic fluid volume has an impact on fetal movement in potentially compromised fetus. Ahn at al demonstrated a 3 to 5 fold increase ultrasonographically detected oligohydramnios in patient with complaints of decreased fetal movements. This relationship becomes extremely important in the postdate pregnancy, where changes of amniotic fluid volume can occur quickly. [ABSTRACT FROM AUTHOR]