Amniotic fluid volume assessment with the four-quadrant technique at 36-42 weeks' gestation.

An ultrasound approach was developed to identify normal amniotic fluid volume. The uterine cavity was divided into four quadrants. With the use of linear-array, real-time B-scanning, the vertical diameter of the largest pocket in each quadrant was measured. The sum of these four quadrants was used to provide a single number for the amniotic fluid volume and termed the amniotic fluid index. This approach is simple, requires little time and gives a semiquantitative estimate of amniotic fluid volume. Based on our observations, the normal amniotic fluid index in term gestation is 12.9 +/- 4.6 cm. Evaluation of the relationship between amniotic fluid volume and fetal outcome is under investigation.