Amniotic fluid index

{{Infobox diagnostic

| name = Amniotic fluid index

| image =

| alt =

| caption =

| pronounce =

| purpose =estimate of amniotic fluid and an indicator of fetal well-being

| test of =

| based on =

}}

Amniotic fluid index (AFI) is a quantitative estimate of amniotic fluid{{cite book |author =Tom C Winter |author2 =Sanders, Roger C. |title=Clinical Sonography: A Practical Guide |publisher=Lippincott Williams & Wilkins |location=Hagerstown, MD |year=2006 |pages= 502|isbn=0-7817-4869-0 |url= https://books.google.com/books?id=KUd6bLOtrxoC&q=%22Amniotic+Fluid+Index%22&pg=PA502}} and an indicator of fetal well-being. It is a separate measurement from the biophysical profile.

AFI is the score (expressed in centimetres) given to the amount of amniotic fluid seen on ultrasonography of a pregnant uterus. To determine the AFI, doctors may use a four-quadrant technique,{{cite web|url=http://www.perinatology.com/Reference/glossary/A/Amniotic%20Fluid%20Index.htm|title=perinatology.com Glossary|website=www.perinatology.com}} when the deepest, unobstructed, vertical length of each pocket of fluid is measured in each quadrant and then added up to the others,{{cite book |author =Carr, Phyllis L. |author2 =Ricciotti, Hope |author3 =Freund, Karen M. |author4 =Scott Kahan |title=In a Page Ob/Gyn & Women's Health (In a Page) |publisher=Blackwell Publishers |location=Cambridge, MA |year=2003 |pages= 105|isbn=1-4051-0380-9 |url= https://books.google.com/books?id=YsHwGCYi0YAC&q=%22Amniotic+Fluid+Index%22+Oligohydramnios&pg=PA105}} or the so-called "single deepest pocket" technique.{{Cite web | url=http://www.americanpregnancy.org/pregnancycomplications/lowamnioticfluidoligohydramnios.htm |title = Los Bajos Niveles de Líquido Amniótico: Oligohidramnios|date = 2012-04-27}}

An AFI between 8 and 18 cm is considered normal.{{Cite web | url=http://www.gynob.com/biopamfl.htm | title=PRO: Amniotic Fluid - Biophysical Profile - the virtual ObGyn office}} Median AFI level is approximately 14 cm from week 20 to week 35,{{cite web|url=http://www.fetalanomalies.org/Fluid.html|archive-url=https://web.archive.org/web/20190204065759/www.fetalanomalies.org/Fluid.html|archive-date=2019-02-04|title=Amniotic Fluid Index}} when the amniotic fluid begins to reduce in preparation for birth. An AFI smaller than 5–6 cm is considered as oligohydramnios. The exact number can vary by gestational age. The fifth percentile for gestational age is sometimes used as a cutoff value.{{cite journal |vauthors =Griffin M, Attilakos G, Greenwood R, Denbow M |title=Amniotic fluid index in low-risk, post-dates pregnancies |journal=Fetal Diagn. Ther. |volume=26 |issue=4 |pages=212–5 |year=2009 |pmid=20029220 |doi=10.1159/000265554 |s2cid=33665604 |url=https://www.karger.com/Article/PDF/000265554|url-access=subscription }}

An AFI larger than 24–25 cm is considered as polyhydramnios.{{cite book |author =Sylvia Dobo |author2 =Mitchell King |author3 =Lipsky, Martin S. |author4 =Jeff Susman |title=Family Medicine Certification Review |publisher=Blackwell Publishers |location=Cambridge, MA |year=2003 |pages= 133|isbn=1-4051-0329-9 |url= https://books.google.com/books?id=ETS89YmvaIkC&q=%22Amniotic+Fluid+Index%22+Polyhydramnios&pg=PT144}}

Causes of low amniotic fluid

There are many things that can cause low AFI, these include:

Leaking or rupture of membranes: Leaking or rupture of membranes may be caused by a gush of fluid or a slow constant trickle of fluid. This is due to a tear in the membrane. Premature rupture of membranes can also result in low amniotic fluid levels.
Placental problems: Placental problems may cause low amniotic fluid. If the placenta is not providing enough blood and nutrients to the baby, then the baby may stop recycling fluid.
Birth defects: Birth defects may occur if the fetus has problems with the development of the kidneys or urinary tract, which could cause little urine production, and it can lead to low levels of amniotic fluid.
Maternal complications: Maternal complications may cause low amniotic fluid. Some factors such as hypertension, diabetes, dehydration, preeclampsia, and chronic hypoxia in a woman can have an effect on amniotic fluid levels.

References

Category:Tests during pregnancy