Spectrophotometric analysis of amniotic fluid in Rh immunised pregnancies

A total of 307 amniotic fluid analysis done in 344 Rh negative immunised mothers showed that 46, 83 and 178 delta OD values at 450 millimicrons fell in the upper, middle and lower zones of Liley's charts respectively. The correlation of spectrophotometric analysis with the condition of the baby at birth was about 95 per cent in the upper and lower zones. In the middle zone, however, it was about 75 per cent only. Also, in 7 women in whom the OD at 450 millimicrons fell in the middle zone, the babies were found to be Rh negative; in another baby, the OD difference fell in upper zone. In spite of these limitations amniotic fluid examination seems to be an important single guide to severity, being superior to other parameters like previous obstetric history, antibody titre alone and Liley's charts, which are still widely used.