Coombs' testing and neonatal hyperbilirubinemia

Does strengths of a positive direct antiglobulin test predicts the need for phototherapy and duration of phototherapy? - a single center, retrospective study

BACKGROUND

Use of Direct Antiglobulin test (DAT) in management of neonatal hyperbilirubinemia is conflicting.

OBJECTIVE

whether strength of positive DAT predicts the need for phototherapy, duration of phototherapy and need for major interventions.

METHODS

We retrospectively collected data on all DAT positive neonates with birth gestational age ≥32 weeks over six years (2014-2019). Data regarding blood group, DAT and clinical details were obtained from a hospital database. We also collected data on serial hemoglobin and other relevant laboratory parameters. We also collected data on infants receiving major interventions such as exchange transfusion, in-utero transfusion, immunoglobulins, and postnatal transfusion for the duration of the study period. All of these infants were electronically followed up for a period of 6 weeks. This study was approved by institutional audit authority. All the statistics were performed using SPSS software.

RESULTS

Out of 1285 DAT tests performed, only 91 infants were positive (7%), and 78 DAT positive infants were available for analysis. There were 54 infants with DAT (1+), 15 infants with DAT (2+), 7 infants with DAT (3+) and 2 infants with DAT (4+). There was no significant statistical difference in terms of need for phototherapy, duration of phototherapy, need for major interventions and hemoglobin levels at different time points between the groups (DAT 1+ Vs DAT ≥2+; DAT ≤2+ Vs DAT >2). A Total of 10 infants received major intervention, with one infant receiving all three interventions (DAT 3+ with significant maternal antibodies), 2 additional infants (both DAT1+) received exchange transfusion, 6 additional infants received immunoglobulin (2 infants: DAT 2+; 4 infants: DAT 1+) and one additional infant (DAT 1+) with significant maternal antibodies received a postnatal transfusion.

CONCLUSION

Strength of a DAT did not predict the need for phototherapy, duration of phototherapy, and the need for major hemolysis related intervention in the first 6 weeks of life.

Direct antiglobulin test in the prediction of hyperbilirubinemia and predischarge bilirubin levels in infants with mother-infant blood type incompatibility

BACKGROUND

This research evaluated the association between the mother-infant blood type or rhesus (ABO or Rh) incompatibility, the pattern of neonatal jaundice, and serum bilirubin (TSB) values obtained prior to discharge from hospital of healthy born neonates with gestational age >34 weeks and birth weight >2000 g.

METHODS

We utilized a laboratory and neonatal database to identify the cord blood ABO/Rh and direct antiglobulin test (DAT) and TSB measured during hospitalization and re-admission with hyperbilirubinemia for phototherapy treatment. We used hour-specific TSB to analyze the TSB levels for ABO/Rh compatibility and isoimmunization using chi-square, analysis of variance, and regression models.

RESULTS

Of the 901 infants studied, 158 (17.5%) had ABO/Rh incompatibility, including 27 with positive DAT. Hyperbilirubinemia was diagnosed in 33.3% DAT positive, 6.9% DAT negative, and 4.6% of infants with compatible blood types. Increased predischarge TSB was observed in DAT positive infants at 48-72 h of postnatal age (P < 0.001). After controlling for age at TSB testing and weight loss percentage, multiple regression analysis did not show any impact of ABO/Rh incompatibility and DAT results on the predischarge TSB levels.

CONCLUSION

Blood type incompatibility increases the frequency of hyperbilirubinemia only in the DAT-positive infants. Irrespective of the isoimmunization status, it does not significantly affect the level of predischarge TSB.

An Automated Method for Direct Antiglobulin Testing and the Resulting Amount of Phototherapy Used at a Large Academic Medical Center

OBJECTIVE

To evaluate how clinical practice was affected by the change in direct antiglobulin testing (DAT) methodologies and subsequent stronger reported DAT results at our large academic medical center.

METHOD

We retrospectively reviewed DAT results of umbilical cord blood from infants with blood type A or B born to mothers with antibody-negative type O blood, based on records kept at the University of Alabama at Birmingham (UAB) Hospital, a 1400-bed academic medical center.

RESULTS

We randomly chose 50 neonates with positive DAT results who had been tested using the tube method and 50 whose testing had used the gel method. Although 86% of results with the tube method were positive microscopically, 52% and 40% of the DAT results with the gel method were 1+ and 2+ positive, respectively. Further, we observed an increase in the number of neonates treated with phototherapy who had been tested using the gel method.

CONCLUSION

We report that DATs performed using the gel method had increased DAT strength compared with tube testing, which led to increased use of phototherapy by our clinical colleagues.

How to use: the direct antiglobulin test in newborns

The direct antiglobulin test (DAT) detects the presence of immunoglobulin, complement or both bound to the red blood cell membrane. The test, historically called the 'Coombs test', was first described in 1945 by Cambridge immunologist Robin Coombs. Suspected haemolytic disease of the newborn, due to either Rhesus disease or ABO incompatibility, is one of most common reasons for requesting a DAT in newborns. In this article, we discuss the physiological background and technological background of the DAT. We also provide a clinical framework for a rational approach to the use and interpretation of the DAT in newborns.