Amniotic fluid: the value of prenatal analysis. 1.

Abstract

Amniotic fluid analysis is an integral tool in assessing the normalcy or abnormalcy of the unborn child. Amniotic fluid is normally clear but may be faintly milky or opalescent especially during the last trimester of pregnancy. A yellow or reddish brown color suggests fetal complication as does the presence of meconium in the fluid. Amniotic fluid osmolality can be used in assessing fetal maturity and perinatal outcome. Osmolality of 250 m0sm/kg or less generally indicates a fetus of 37 weeks or more gestational age; such a value however should not be considered an absolute criterion because of the wide scatter of normal values. A decrease in amniotic fluid osmolality can be attributed to a change in sodium electrolyte concentration. However electrolyte concentrations in the amniotic fluid have not been significantly correlated with the pathologic states of pregnancy. Other components of amniotic fluid are: 1) acid-base balance the significance of which is little understood; 2) urea uric acid and creatinine which are mainly fetal excretory products; 3) proteins changes in the levels of which can be clinically helpful in managing an Rh-negative sensitized pregnancy; 4) amino acids which have potential for use in prenatal diagnosis of metabolic diseases (e.g. cystinuria glycinuria phenylketonuria); 5) lipids which may provide an accurate basis for assessing fetal lung maturity and may play a role in the coagulopathy associated with amniotic fluid embolism and; 6) prostaglandins the significance of which is yet to be understood.