Prediction of Neonatal Jaundice by Study of Cord Blood Bilirubin and Serum Bilirubin at 24 Hours of Life

Abstract

BACKGROUND Jaundice is yellowish discolouration of the skin, the mucous membranes or the eyes. It is caused by high levels of the chemical bilirubin in blood, a by-product of destruction of old red blood cells. A newborn baby's liver is not fully matured, so jaundice is common during a baby's first few days of life 1 Since bilirubin is potentially toxic to the central nervous system, early detection and appropriate management of neonatal jaundice (NNJ) is of paramount importance 2. Hence early detection of neonatal jaundice is an important issue. The present study was conducted to find out the critical value of serum bilirubin in the cord blood and at 24 hrs. in predicting the subsequent development of hyperbilirubinemia in healthy newborn babies. METHODS Cord blood sample and blood sample at 24 hours were collected from all 200 babies. After 24 hours and up to 5 th post-natal day, blood samples for serum bilirubin estimation were taken from those babies who were clinically suspected to be having jaundice. RESULTS Total serum bilirubin > 2.3 mg/dl has sensitivity of 75.3% (95% CL 65.2% to 83.6%), specificity of 81.3% (95% CL 72.6% to 88.2%), positive predictive value of 77.8 (67.8 to 85.9), negative predictive value of 79.1% (70.3% to 86.3). The diagnostic ability of TSB at 24 hrs. to predict the need for phototherapy shows that TSB > 5.3 mg/dl, has sensitivity of 87% (95% CL 78.5% to 93.2%), specificity of 67.3% (95% CL 57.5% to 76%), positive predictive value of 69.8 (60.6 to 78.0), negative predictive value of 85.7 (87.5 to 85.4). CONCLUSIONS The time to reach maximum total serum bilirubin level after birth is 3 rd postnatal day in our study. So, the baby in need of phototherapy has to be identified earlier to 3 rd postnatal day. A total serum bilirubin level prior to 3 rd day which can predict the later need of photo-therapy in a given baby will have clinical utility. The optimum cut off value of total serum bilirubin in cord blood which can predict the need for phototherapy is > 2.3 mg/dl and value of total serum bilirubin at 24 hrs which can predict the need for phototherapy is > 5.3 mg/dl. So, these at-risk babies should be observed carefully for the need of phototherapy.