An improved, rapid procedure for the determination of amniotic fluid bilirubin and its use in the prediction of the course of Rh-sensitized pregnancies

A simple, rapid chloroform extraction method for analyzing amniotic fluid samples in Rh sensitization is presented. It consists of the extraction of the unconjugated bilirubin into chloroform and the determination of the bilirubin concentration in the CHCl3 layer. The values show excellent correlation with those obtained by the method of Liley for estimating the 450 mμ peak. No interference occurs in samples containing excessive heme pigments, meconium, and turbidity. The retrospective evaluation of 137 pregnancies from which 276 amniotic fluid specimens were analyzed with the chloroform extraction technique is presented. The patients are grouped according to clinical severity of the disease in the infant at birth. A prediction graph has been constructed which can be used to aid in the management of individual Rh-sensitized pregnancies. The importance of serial amniotic fluid samples is emphasized.