Diagnostic accuracy of transcutaneous bilirubinometry versus serum bilirubin level

Abstract

Objective: To assess the diagnostic accuracy of transcutaneous bilirubinometry over serum bilirubin level in newborns with hyperbilirubinemia.

Study design:  Cross-sectional study.

Place and duration of study: Department of Neonatology, Children Hospital, PIMS Islamabad for six months from 01-09-20 to 28-02-21.

Patients and method: Total 150 Neonates of either gender having clinical jaundice were included in the study. Neonates who took treatment for Hyperbilirubinemia, gestational age of < 33 weeks, birth weight < 1500 gm, having major congenital malformations, and neonates of a jaundiced mother were excluded from the study. MBJ-20  transcutaneous bilirubinometer was used for transcutaneous bilirubinometry. The first of three measurements with the MBJ-20 was taken, and the average mean was taken as the final reading. Readings were compared with serum bilirubin levels at the same time.

Results: There were 80 (53.3%) males and 60 (46.6%) females. The mean gestational age was 37±3.4 weeks. The postnatal age at the time of presentation was 52 (34.7%) patients within three days, 80 (53.3%) patients within 4-7 days, and 18 (12%) presented after the first week.. There were 32 newborns (21.3%) weighing less than 2.5 kg and 118 neonates weighing more than 2.5 kg. Forty-five (30%) patients had a transcutaneous bilirubin level of less than 10mg/dl, 77 (51.3%) patients had between 11-15 mg/dl, and 28 (18.7%) patients had a level of more than 16 mg/dl. There were 52 (34.7%) patients with a serum bilirubin level less than 10 mg/dl, 73 (48.7%) patients with a level between 11 and 15 mg/dl, and 25 (16.6%) patients with a level greater than 16 mg/dl. Serum bilirubin levels varied from 2-21.7 mg/dL, whereas transcutaneous bilirubin levels ranged from 1.4 to 22.1 mg/dL. Transcutaneous bilirubin and serum bilirubin had a Pearson Correlation coefficient (r) of 0.776 (p-value < 0.0001). The calculated sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 95.59%, 78.57%, 97.74%, 64.71%, and 94.00%, respectively.

Conclusion:

Transcutaneous bilirubinometry is a low-cost, noninvasive, and accurate screening test for hyperbilirubinemia with a high sensitivity specificity and positive predictive value (PPV).