Amniotic Fluid Creatinine Concentrations Research Articles

Amniotic fluid beta-2-microglobulin in normal and complicated pregnancies. Correlation with gestational age, creatinine concentration and L/S ratio.

The beta-2-microglobulin concentrations in 127 aminotic fluid samples, obtained during weeks 32-42 of normal pregnancies (n = 58) and complicated pregnancies (n = 69), were measured and correlated with gestational weeks, amniotic fluid creatinine concentrations and L/S ratios. A significant (p less than 0.001) decrease of beta-2-microglobulin concentration occurred from week 32 to 34 of normal pregnancies, after which the beta-2-microglobulin level was unchanged. There were no significant correlations between beta-2-microglobulin concentrations and amniotic fluid creatinine concentrations of LK/S ratios. The beta-2-microglobulin content was elevated in samples obtained from diabetic and toxemic pregnancies. Measurement of beta-2-microglobulin in amniotic fluid seems to be of limited value for determining fetal age, but it may be useful in estimating fetal renal maturity.

Evaluation of fetal maturity by amniotic fluid creatinine concentrations and lecithin/sphingomyelin ratio.

In a material of 144 samples of amniotic fluid from the last trimester, creatinine concentration, lecithin/sphingomyelin (L/S) ration and their correlation, have been examined. Amniotic fluid creatinine concentration (a.f.c.) increased gradually through the last trimester up to 39 weeks (273-279 days p.m.) with median values of 2 mg/100 ml at 37 weeks and 2.5 mg/100 ml at 39 weeks gestation. The great range makes a.f.c. of doubtful value in assessment of gestional age in individual samples. The correlation between a.f.c. and L/S ratio was highly significant (Kendall's T=0.56). Even so lung maturity cannot be predicted from a.f.c. A low L/S ratio with a.f.c. larger than or equal to 2 mg/100 ml was found in 8-9%, while a.f.c. 1.1-1.9 mg/100 ml was combined with L/S ratios larger then or equal to 2 in a great number of cases. A.f.c. less than 1.1 mg/100 ml was invariably correlated with low L/S ratios.

Determination of amniotic fluid phospholipids for the diagnosis of fetal maturation

In 111 patients, the L/S ratio, the concentration of phospholipids, lecithin, phosphate in total lipids, creatinine, and the foam test were determined at various periods of gestation by amniocentesis. Surface tension of amniotic fluid was measured by two different techniques (the angle of intersection and the bubble disappearance rate). Each test, with the exception of the angle of intersection and the concentration of phosphate in total lipids, correlates significantly with gestational age and with the L/S ratio of Gluck and Kulovich. The S.D. of each test is large. From the data it is concluded that the determination of amniotic fluid creatinine concentration and the use of the foam test provide fast, cheap, and reliable information when the tests are positive for maturation. If the amniotic fluid tests are in the immature range, amniocentesis should be repeated.

Amniotic fluid creatinine in the Rh-sensitized pregnancy

Amniotic fluid creatinine concentrations were analyzed in 165 samples from 62 normal and 32 Rh (D)-sensitized pregnancies. A close correlation between maturity and amniotic fluid creatinine was observed in the uncomplicated pregnancies, a concentration of less than 1.8 mg. per cent being predictive of fetal immaturity. In contrast, amniotic fluid creatinine was significantly lower in the sensitized pregnancies, values less than 1.8 mg. per cent commonly (11 of 15) accompanying fetal maturity. In addition, a paradoxical decline in concentration with advancing gestation was shown to be associated with serious perinatal morbidity and a 40 per cent risk of perinatal death. These data suggest that serial analysis of creatinine concentrations in conjunction with routine analysis of amniotic fluid bilirubin4 and total osmolality5 may be of significant value in the prospective clinical management of the Rh-sensitized pregnancy.

Relationship between amniotic fluid triglyceride levels and fetal maturity

Triglyceride determinations have been made in 100 samples of amniotic fluid, and the results have been correlated with gestational age and fetal weight. When the triglyceride level is 2.00 mg. per cent or greater, the correlation with a mature fetus is good. However, values less than 2.00 mg. per cent are associated with both mature and immature fetuses. Low values cannot be used as indicative of fetal prematurity. Levels of 2.00 mg. per cent or greater showed good correlation with amniotic fluid creatinine concentrations of 1.8 mg. per cent or greater, Δ O.D.450 measurement of 0.02 or less, and orange cell counts of 10 per cent or greater. As a test for fetal maturity, amniotic fluid triglyceride determination offers no advantage over the standard amniotic fluid analyses; however, this determination may be useful as an additional parameter upon which intelligent decisions of intervention can be made.

Amniotic fluid examination as an aid in the assessment of gestational age

Amniotic fluid creatinine and bilirubin concentrations and percentage of fetal sebaceous cells were determined simultaneously in 65 normal obstetric patients who had a reliable menstrual history. These constituents in the amniotic fluid were then compared to the gestational age determined from the menstrual history and by physical and neurological examinations of the newborn infant. Of the three, amniotic fluid creatinine concentration was the most reliable. After 36 weeks’ gestation, the creatinine concentration was 1.8 mg. per cent or greater.