The Rh problem in obstetrics and a new concept of its management using amniocentesis and spectrophotometric scanning of amniotic fluid

Abstract

1. Amniocentesis has been performed on more than 900 occasions in a group of over 300 Rh-immunized pregnant women without a major mishap to either the fetus or the mother. A detailed account of the antepartum management of these cases and the clinical outcome in 245 completed pregnancies is presented. The total perinatal loss (stillbirths and neonatal deaths) due to hemolytic disease was 8 per cent of the total 245 immunized pregnancies, and 9 per cent of the total number of affected Rh-positive infants (211 pregnancies). The previous perinatal mortality rate from hemolytic disease at this hospital was 30 per cent of the total number of affected Rh-positive infants. In addition, only one first affected baby was lost in this study as a result of hemolytic disease, and no unnecessary inductions of premature labor nor cesarean sections were performed to deliver unaffected infants.2. In the antepartum management of a Rh-immunized pregnancy, the spectrophotometric scanning of the amniotic fluid appears to be the most clinically useful procedure. However, it is suggested that the true value of this procedure can only be realized by repeating the test at biweekly intervals (or sometimes at weekly intervals); in order to minimize the risk of amniocentesis, the placenta should be localized by both the radioisotope and thermograph methods.3. The physical characteristics and the clinical interpretation of the spectrophotometric tracings has been discussed in detail.4. There appears to be a better correlation between the spectrophotometric tracings within 10 days of delivery and the clinical condition of the infant at birth, as assessed by the Apgar score and the presence or absence of circulatory failure, than with the level of cord hemoglobin and cord bilirubin, etc. It is suggested that the standard evaluation of the severity of hemolytic disease of the newborn should be revised to include the general condition (as assessed by recent amniotic fluid analysis) of the infant.5. The principal value of amniocentesis and spectrophotometry is to determine the fetal outcome (survival or death) and not the level of hemoglobin at birth.