USG Scan - Amniotic Fluid Index Test

An ultrasound examination is used to examine the amount of amniotic fluid. It is an integral part of antenatal ultrasound during targeted anatomy examinations, screening exams and in tests assessing the well-being of the fetal. The amniotic fluid index is calculated by randomly dividing the uterus into four imaginary quadrants. The umbilicus serves as the dividing point between the lower and upper halves and the linea nigra divides the uterus into the left and right halves. Amniotic fluid index is a part of the biophysical profile. Abnormal amniotic fluid volume has been associated with an increased risk of several adverse perinatal outcomes and prenatal mortality which includes abnormal birth weight, fetal abnormalities, premature rupture of membranes, and increased risk of obstetric interventions.

It is always advisable to carry the prescription letter and all the pension Healthcare card or Medicare along with you for the examination. You need to know all the relevant information before performing the test. Special instruction would be provided by the doctor before your test. You need to cease your eating four to six hours and also avoid drinking two hours before the examination. If you are already on some medications, then it can be taken orally with a small amount of water. You also need to reach the clinic on time so that sufficient time is available for performing the examination.

Amniotic fluid index ultrasound is mainly done to test the well-being of the fetal. Amniotic fluid index is used to find out the result of overdiagnosis of oligohydramnios which leads to unnecessary interventions like labor induction etc, and it often contributes to increased morbidity without an improvement in perinatal outcomes. Too much or too little of amniotic fluid may cause harm to both mother and baby and can be signs of some other problems. The ultrasound machine scans the uterus and finds out the amount of amniotic fluid around the baby.

The ultrasound procedure is carried out by a sonographer and takes around 30-60 minutes for the examination. You need to change into a gown and is asked to lie down in a supine position. Ultrasound gel is rubbed on the area and the examination is performed with the help of convex 3.5 MHz probes. The uterus is randomly divided into four quadrants with the use of linea nigra as a vertical line and a transverse line which passes through the umbilicus. The ultrasound probe is placed in each quadrant and the maximum depth of amniotic fluid is calculated in centimeters excluding the small fetal parts and cord loops. The final amniotic fluid index is obtained by adding the values of all the four quadrants.