How to measure AFI

Amniotic fluid measurement.
Technique
• uterus is divided into four imaginary quadrants with linea nigra and umbilicus acting as the vertical and the horizontal axis respectively
• the deepest pocket devoid of umbilical cord and fetal parts is measured in the vertical dimension
• measurement of the four pockets is in centimeters
• sum of all the four quadrant measurements is AFI
• normal AFI values range from 5 to 25 cm

1.                  Amniotic fluid index

The deepest, unobstructed, vertical pocket of fluid is measured in each quadrant in centimeters. The four pocket measurements are then added to calculate the AFI.
Values
• AFI between 8-18 cm is considered normal; median AFI level is ~14 cm from week 20 to week 35, after which the amniotic fluid volume begins to reduce.
• AFI <5-6 cm is considered as oligohydramnios. ...
• AFI >20-24 cm is considered as polyhydramnios

2. Maximum vertical pocket method.

The deepest (maximal) vertical pocket (DVP) depth is considered a reliable method for assessing amniotic fluid volume on ultrasound , It is performed by assessing a pocket of maximal depth of amniotic fluid which is free of umbilical cord and fetal parts.
The usually accepted values are:
• <2 cm: indicative of oligohydramnios
• 2-8 cm: normal but should be taken in the context of subjective volume.
• >8 cm: indicative of polyhydramnios

3. Two diameter pocket method.

The two diameter pocket (TDP) method is an alternative method of assessing amniotic fluid volumes on ultrasound. However, it is not thought to be good predictor of adverse neonatal outcome .
Sonographic assessment
• TDP <15 cm2: indicative of oligohydramnios
• TDP 15 - 50 cm2: usually taken as normal
• TDP >50 cm2: indicative of polyhydramnios