The Spectrum of Hemolytic Disease of the Newborn: Evaluating the Etiology of Unconjugated Hyperbilirubinemia Among Neonates Pertinent to Immunohematological Workup

Background and objective The exact burden of hemolytic disease of the newborn (HDN) attributed to neonatal unconjugated hyperbilirubinemia (NUH) in developing nations is still unclear. Still, anti-D is reported to be the most common cause of HDN in India. ABO incompatibility has emerged as a leading cause of exchange transfusion (ET) in many countries. But many centers in our country rely on direct antiglobulin test (DAT) as a screening tool to evaluate immunological causes, whereas advanced immunohematological workup like antibody screening, identification, and elution tests are also required. Early identification of implicated antibodies resulting in HDN can aid in the proper selection of blood units when ET is indicated, and hence also in managing the subsequent pregnancy. This study focused on determining the causes of neonatal hyperbilirubinemia (NH), especially with respect to immunohematological evaluation. This cross-sectional study was conducted on 240 neonates requiring neonatal intensive care unit (NICU) support for NUH at a tertiary care hospital. Materials and methods Demographic data, along with detailed history pertaining to the cause of hyperbilirubinemia, was collected. Clinical and laboratory evaluation and complete immunohematological work including DAT, heat elution, antibody screening, antibody identification, and Rh Kell phenotyping were performed from neonate blood samples. Data were analyzed using SPSS Statistics version 19 (IBM Corp., Armonk, NY). Results Pathological jaundice was more common (62.1%) than physiological jaundice (37.9%). The various pathological causes identified were HDN (42.6%), sepsis (12%), cephalohematoma (5.4%), and idiopathic (1.7%). Among HDN cases, ABO incompatibility (39.2%) was the most prevalent cause, followed by Rh HDN and G6PD deficiency (1.7% each). DAT was positive in only 14 cases out of 94 ABO-incompatible cases. Elution revealed antibodies in four DAT-negative neonates with ABO incompatibility and more specificity to the OA setting. DAT was positive with 100% sensitivity in Rh HDN cases (n=4). Elution demonstrated the presence of anti-D (n=2), anti-D + anti-C (n=1) and anti-E (n=1), confirming Rh HDN. DAT strength was found to be significantly associated with hemoglobin (Hb) level (p=0.048). The majority of cases were treated with phototherapy only (94.1%), and 10 cases received both ET and phototherapy. Four neonates' condition improved without any intervention. Conclusion This study highlighted the shift in the trend from Rh HDN to ABO incompatibility as the cause of hemolytic jaundice in NICU neonates. Elution tests can aid in the diagnosis of DAT-negative ABO-incompatible hemolytic anemia. Early diagnosis, along with timely intervention and appropriate measures, can prevent neonatal morbidity and mortality. Negative DAT does not rule out HDN. Sensitive techniques like elution must be used in the presence of clinical suspicion.