BILIRUBIN - amniotic fluid

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Specimen: 2 mL amniotic fluid. Protect from light.

Method: Spectrophotometry.

Reference Interval: Varies with gestational age. Some laboratories express the result as mmol/L, others as an ODD450 (optical density difference at 450 nm).

Application: Investigation of pregnancies at risk for haemolytic disease of the newborn .

Interpretation: Increased levels indicate haemolysis. A number of different graphs have been published correlating degree of risk with amniotic fluid bilirubin level at various gestational ages. Bleeding into the amniotic fluid invalidates results.

Reference: Spinatto JA et al. Am J Obstet Gynecol 1991; 165: 1030-1035.