What is the Normal Range of Amniotic Fluid Index?

The amniotic fluid index is an important indicator of whether the fetus is healthy in the uterus, and it is particularly important to understand the standard of the amniotic fluid index. What is the normal range of amniotic fluid index?

Most hospitals use ultrasound to understand the status of amniotic fluid, and use the amniotic fluid index method to determine whether the amniotic fluid is normal.

The method is by dividing the uterus into four quadrants, measuring the maximum depth of amniotic fluid in each quadrant, and then adding up to sum up.

The total value of the amniotic fluid index within the range of 8 to 27 cm is normal, less than 8 is oligohydramnios (too little amniotic fluid), and greater than 24 is polyhydramnios (too much amniotic fluid).

Normal range of 32-week amniotic fluid index

In different stages of fetal development, the source of amniotic fluid is different, and the standard of amniotic fluid index is also different. So, what is the normal range of a 32-week amniotic fluid index?

At 32 weeks, the fetus gradually grew up, and the bones and organs developed more mature and strong. At this time, the fetus can already hear the sounds outside the mother. 

32 Weeks Index:

  • Body length: 42-46 cm 
  • Weight: about 2 kg-2.7 kg
  • B-ultrasound tips; Double top diameter: 7.79-8.18 cm
  • Humerus: 5.54 cm
  • Femur: 6.55 cm
  • Bust: 22.3 cm
  • Abdominal circumference: 25.36 cm
  • Normal range of amniotic fluid index: 15-16 cm

38 week normal range of amniotic fluid index

At 38 weeks, the fetus has developed to near maturity. The skin is pink, the subcutaneous fat is full, the skin is covered with fetal fat, and the fetal head drops into the pelvis. Ready to be born. The data representing the healthy development of the fetus at this time are as follows:

  • Body length: 50-55 cm
  • Weight: about 2.8-3.6 kg
  • Double top diameter: 8.40-9.31 cm
  • Humerus: 5.59-6.29 cm
  • Femur: 6.76-7.62 cm
  • Bust: 23.05-24.32 cm
  • Abdomen: 25.89-28.11 cm
  • The normal range of amniotic fluid index at 38 weeks: 15.6-14.6 cm.

What is the difference between amniotic fluid index and amniotic fluid depth?

The depth of amniotic fluid refers to the vertical depth of the largest amniotic pool by B-ultrasound, less than 2cm means too little amniotic fluid, and more than 8cm means too much amniotic fluid. 

The amniotic fluid index (AFI) divides the uterus into four quadrants: upper left, upper right, lower left, and lower right. The sum of the maximum vertical depth of the dark areas of the four quadrants is AFI. If AFI is greater than 24cm, it is diagnosed as excessive amniotic fluid. Suspected amniotic fluid is excessive.

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