Amniotic fluid index

Last revised by Jeremy Jones ◉ on 26 Sep 2021

Citation, DOI, disclosures and article data

Citation:

Weerakkody Y, Jones J, Hacking C, et al. Amniotic fluid index. Reference article, Radiopaedia.org (Accessed on 23 Sep 2023) https://doi.org/10.53347/rID-13597

DOI:

https://doi.org/10.53347/rID-13597

Permalink:

https://radiopaedia.org/articles/13597

rID:

13597

Article created:

25 Apr 2011, Yuranga Weerakkody ◉

Disclosures:

At the time the article was created Yuranga Weerakkody had no recorded disclosures.

View Yuranga Weerakkody's current disclosures

Last revised:

26 Sep 2021, Jeremy Jones ◉

Disclosures:

At the time the article was last revised Jeremy Jones had no recorded disclosures.

View Jeremy Jones's current disclosures

Revisions:

27 times, by 14 contributors - see full revision history and disclosures

Systems:

Obstetrics

Sections:

Approach

Synonyms:

Amniotic fluid index (AFI)

The amniotic fluid index (AFI) is an estimate of the amniotic fluid volume in a pregnant uterus. It is part of the fetal biophysical profile.

Technique

the uterus is divided into four imaginary quadrants with the linea nigra and a mediolateral line running through the umbilicus acting as the vertical and the horizontal axes respectively
the deepest pocket devoid of an umbilical cord and fetal parts is measured in the vertical dimension
measurement of the four pockets is in centimeters
the sum of all the four quadrant measurements is the AFI
normal AFI values range from 5 to 25 cm

Values

The normal range for amniotic fluid volumes varies with gestational age. Typical values include:

AFI between 5-25 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 cm is considered to be oligohydramnios
- value changes with age: the 5^th percentile for gestational ages is most often taken as the cut-off value, and this is around an AFI of 7 cm for second and third-trimester pregnancies; an AFI of 5 cm is two standard deviations from the mean
AFI >25 cm is considered to be polyhydramnios