Serum and amniotic fluid heat labile alkaline phosphatase and aminotransferases in association with meconium stained liquor. On their origin, distribution and clinical use.

A method for detecting meconium in the amniotic fluid is described. Samples of maternal serum, cord serum and amniotic fluid were tested for alkaline phosphatase and transaminases activity in 32 healthy, term gravidas during labor in whom meconium stained amniotic fluid was found. The values obtained were compared to those of a control group consisting of 32 normal term pregnancies in whom the amniotic fluid was clear. Mean alkaline phosphatase activity was significantly higher in the study group in all three compartments - maternal, fetal and amniotic fluid. A significant and positive correlation between levels of alkaline phosphatase in the amniotic fluid and in maternal serum was found in the study group. Alkaline phosphatase value of 550 IU/L or more in maternal serum was diagnostic and levels between 350--500 IU/L were highly suggestive for the presence of menconium in the amniotic fluid. Mean levels of transaminases (SGOT and SGPT) were similar in the two groups and all were within normal range. The origin of alkaline phosphatase and the mode of transfer of the three enzymes are also discussed. It is suggested that this method can also be used during the third trimester of pregnancy.