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NORMAL AMNIONIC FLUID VOLUME .......... .....225
PHYSIOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... 225
SONOGRAPHIC ASSESSMENT . .......... . .i..226
HYDRAMNIOS ......... ...i...i..i......... .....227
OLIGOHYDRAMNIOS ..i........ .... ....... .....230
BORDERLINE OLIGOHYDRAMNIOS ........... ...i.. 232
It is generaly agreed that amniotic luid represents in great part a transudation from the matenal vesses, but many authorities consider that a portion of it is derived rom urinay secretion of the oetus.
-J. Whitridge Williams (1903)
At the time Williams wrote this, the fetal kidney was thought by many to be nonfunctional. Since that time, however, much has been learned of this complex multifunctional liquor amnii. mnionic fluid serves several roles during pregnancy. Fetal breathing of amnionic fluid is essential for normal lung growth, and fetal swallowing permits gastrointestinal (GI) tract development. Amnionic fluid also creates a physical space for fetal movement, which is necessary for neuromusculoskeletal maturation. It further guards against umbilical cord compression and protects the fetus from trauma. Amnionic luid even has bacteriostatic properties. Abnormalities of volume may result from fetal or placental pathology-indicating a problem with luid production or its circulation. These volume extremes may be associated with increased risks for adverse pregnancy outcome.