Comparison of Diagnostic Accuracy of Different Sites for Transcutaneous Bilirubin Measurement in Early Preterm Infants.

Objective: To evaluate correlation of transcutaneous bilirubin (TcB) measured at different body sites with serum total bilirubin (TSB) in early preterm infants.

Methods: This hospital based prospective comparative study was carried out in the Department of Pediatrics, SMS Medical College, Jaipur between April 2015 to March 2016. Early preterm infants with gestational age ≤ 34 weeks in whom clinical jaundice was significant mandating TSB measurement were included in the study. Study subjects who met the inclusion criteria were chosen consecutively. Neonates in whom phototherapy was already initiated and those with poor perfusion (capillary refill time > 3 s) were excluded from the study. All the measurements were carried out within first postnatal week. Transcutaneous bilirubin was measured from three sites: forehead, sternum and interscapular region and within 15 min of TcB measurement, blood samples were taken and serum bilirubin level was calculated.

Results: Correlation coefficients of transcutaneous bilirubin measured from forehead, sternum and interscapular sites were 0.82, 0.84 and 0.86 respectively. TcB measured from all the three sites correlated significantly with serum bilirubin (p < 0.001), but the correlation was best at interscapular site. Sensitivity, specificity and false negative rates were calculated with respect to starting phototherapy. Interscapular site had the highest sensitivity and lowest false negative rate (87.6 and 12.4% respectively) as compared to forehead (79.2 and 20.8% respectively) and sternum (87.1 and 12.9% respectively).

Conclusions: Transcutaneous bilirubin measurement is an acceptable method for identification of hyperbilirubinemia requiring treatment in early preterm newborns. The authors recommend interscapular region as a reliable site in infants of gestational age ≤34 wk for measuring transcutaneous bilirubin.