EXAMINATION OF LIQUOR AMNII AS A METHOD OF PREDICTING SEVERITY OF HAEMOLYTIC DISEASE OF NEWBORN

Prenatal diagnosis: the irresistible rise of the 'visible fetus'

Prenatal diagnosis was developed in the 1970s, a result of a partly contingent coming together of three medical innovations-amniocentesis, the study of human chromosomes and obstetrical ultrasound-with a social innovation, the decriminalization of abortion. Initially this diagnostic approach was proposed only to women at high risk of fetal malformations. Later, however, the supervision of the fetus was extended to all pregnant women. The latter step was strongly favoured by professionals' aspiration to prevent the birth of children with Down syndrome, an inborn condition perceived as a source of suffering for families and a burden on public purse. Experts who promoted screening for 'Down risk' assumed that the majority of women who carry a Down fetus will decide to terminate the pregnancy, and will provide a private solution to a public health problem. The generalization of screening for Down risk increased in turn the frequency of diagnoses of other, confirmed or potential fetal pathologies, and of dilemmas linked with such diagnoses. Debates on such dilemmas are usually limited to professionals. The transformation of prenatal diagnosis into a routine medical technology was, to a great extent, an invisible revolution.

Determination of bilirubin in amniotic fluid: a comparison of some current methods

Three methods for the estimation of bilirubin in amniotic fluid are compared. The within-batch precision and recovery of bilirubin by each method has been studied, and the effects of the presence of haemoglobin, methaemoglobin, and methaemalbumin in varying concentrations have been investigated. Measurements on amniotic fluid from patients with rhesus isioimmunization have also been compared and regression equations calculated. The results of the three methods agree reasonably well so long as no haemoglobin degradation products are present. It is suggested that in the presence of these products a method involving organic solvent extraction of bilirubin gives the most accurate result.

Six years' experience of the prediction of severity in rhesus haemolytic disease

Prediction charts used in the management of patients suffering from rhesus haemolytic disease are presented and the accuracy investigated for two methods of amniotic fluid analysis. In 468 samples from 141 patients there were 7-9 per cent errors of prediction when both methods were used together but in only four cases (2-8 per cent) was the error thought to have possibly contributed to wrong management.

Assessment of severity of haemolytic disease of the newborn at time of birth

A new cord blood factor has been suggested as a measure of the severity of haemolytic disease of the newborn at birth. One hundred and seventy three cases of Rhesus iso-immunisation have been classified as mild, moderate and severe according to the readings of Optical Density Difference of bilirubin in the liquor amnii and correlated with the cord blood haemoglobin, cord blood serum bilirubin, and the new cord blood factor. The new cord blood factor gave the best correlation.

Liquor bilirubin levels in normal pregnancy: a reassessment of early prediction of haemolytic disease

A comparison was made between chemically and spectrophotometrically determined concentrations of total bile pigment in the liquor amnii. For the period 16 to 26 weeks' gestation the upper limit of normal bile pigment to protein ratio was found to be 0.4. Levels above this would be required as an indication for intrauterine transfusion. In 110 cases of isoimmunization of pregnancy these criteria were applied in the diagnosis of severity of the condition. The ratio of the bile pigment to protein was used rather than a simple bile pigment measurement, and found to be valuable.Nevertheless, it is important to emphasize that fallacious high bilirubin readings may arise by using whatever method, particularly owing to bilirubin and other breakdown products of blood contaminating the liquor.

Protein content of liquor amnii in prediction of severity of haemolytic disease of newborn

Two series of cases of Rh isoimmunization were subjected to liquor examination for bilirubin and protein level. Series 1 comprised 298 cases for the years 1962 and 1963. Series 2 comprised 179 consecutive cases for 1967 in which preliminary selection for liquor examination had been made on the basis of previous history and maternal antibody titre.Bilirubin was measured as the liquor bilirubin ratio, and protein levels were estimated in series 1 by the Folin and Ciocalteau technique and in series 2 by a modified biuret method.Correlations with severity of haemolytic disease in the foetus was made, taking into account the stage of gestation of liquor examination. Both bilirubin and protein levels correlate with severity, but bilirubin is superior to protein. Interrelation of these measurements as bilirubin/protein ratio was inferior to bilirubin level as a method of forecasting severity.