Bilirubin in amniotic fluid

Unfortunately, Perkin-Elmer whcTiras produced this instrument has built the instrument for the purpose of measuring bilirubin in amniotic fluid. As a result, the instriment does not read above a level of approximately 2 mg/100 ml. Therefore, it is necessary to dilute the serum from newborns in order to be read in this instrument. However, if one standardizes by making a 1 to 5 dilution of all newborn serum, one can use this method for screening purposes. One looks forward to the further development of this instrument so that readings can be made over a wide range. 

Still widely used is the method of scanning for bilirubin in amniotic fluid. A scan is run for some distance before and after 450 nm. From the baseline drawn between 2 points (e.g. 

Dubin, A. Application of multi-wavelength spectroscopy to analysis of amniotic fluid bilirubin, in Amniotic Fluid. Natelson, S. Scommegna, A. and Epstein, M. D., ed. John Wiley, N. Y. (1974) pp. 191 - 197. 

The concentration of bilirubin in amniotic fluid is generally too low (-0.01 to 0.03mg/dL 0.17 to 0.51pmol/L) to be measured by standard photometric techniques, but the determination can be done rapidly, accurately, and directly by absorption spectrophotometry. The maximal absorbance of bilirubin is at 450 nm. In the absence of significant amounts of bilirubin, the absorbance spectrum for the amniotic fluid between 365 and 550 nm defines a nearly exponential curve (Figure 54-16). On log-linear axes, the height of the curve at 450 nm above the straight line is linearly proportional to the concentration of bilirubin in the... 

For sensitized mothers with an at-risk fetus, serial titers are performed on maternal serum every month until 24 weeks gestation, then every 2 weeks thereafter. If a critical titer anti-D is detected, then ultrasound Doppler measurements are used to determine the peak velocity of blood flow in the fetal middle cerebral artery. Higher velocity is a strong indicator of fetal anemia. In addition, amniocentesis is performed to assess the bilirubin concentration in amniotic fluid. 

Bilirubin is measured in amniotic fluid to aid in the assessment of fetal risk in rhesus incompatibility. Incompatible red cell antigens can enter the maternal circulation cither from the fetus at the time of delivery or. rarely, because of incompatible blood transfusion specific red cell antibodies are stimulated in the mother. If. as in rhesus disease, the antibodies arc IgG, they cross the placenta and react with specific antigens on the fetal red cell membrane causing haemolysis (Fig.. 3). This is unusual in a first... 

Bilirubin is often present in the liquor amnii when the fetus is affected by hemolytic disease of the newborn (B5). Walker (Wl) examined fresh specimens of amniotic fluid before the 35th week and found that the presence of bilirubin correctly indicated the disease in 94.5 Jo of his afflicted cases. 

Amniotic fluid bilirubin measurements are of value in the detection of risk in rhesus incompatibility. 

This woman should have an amniocentesis performed with bilirubin being measured in her amniotic fluid. In Rhesus incompatibility the amniotic fluid bilirubin concentration will rise because of the destruction of fetal red cells. 

Conjugated bilirubin in rat serum and human amniotic fluid LiChrosorb SI 60, S Jim Gradient from 0 to 1% methanol in chloroform/acetic acid (99.5 0.5) in 6 min UV 430 nm 144... 

Rosenthal, S. M., N. Blankaert, P. M. Kabra, and M. M. Thaler. 1981. Liquid chromatographic determination of bilirubin and its conjugates in rat serum and human amniotic fluid. 

In 1967, colorimetric determination of bilirubin content of amniotic fluid was found to provide a reliable and sensitive measurement of the degree of erythroblastosis in the fetus. The discovery that the uterine content could be collected without endangering survival of the fetus led to using similar techniques in the study of hereditary disease, in particular detectable chromosomal anomalies and identifiable inborn errors of metabolism [195, 196]. 

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