EVALUATION OF TRANSCUTANEOUS BILIRUBINOMETRY IN TERM NEONATES AT THE LAGOS STATE UNIVERSITY TEACHING HOSPITAL, IKEJA, LAGOS

Abstract

Jaundice is the yellowish discoloration of the skin and mucous membranes or the visible
manifestation as a result of elevated serum bilirubin. The serum bilirubin can be estimated
using a technique that is real-time, non-invasive, painless, fast, and relatively inexpensive
technique which is transcutaneous bilirubinometry (TcB). There is a paucity of published
research data in Nigeria on the correlation between TcB and TSB. The aim of this study was to
determine the correlation of TcB with TSB and to identify the site that correlates most with
TSB measurements in a group of term Nigerian neonates at the Lagos State University
Teaching Hospital (LASUTH) using the Konica Minolta JM 103.
One hundred and fifty consecutive neonates that presented at the Neonatal unit of the hospital
were recruited for the study after checking them with set inclusion and exclusion criteria.
Detailed information obtained for the subjects’ parents and the physical examination findings
of the subjects were also recorded. The TcB readings of the subjects were taken on the forehead,
sternum and abdomen of the calm neonate in a supine position and blood samples for TSB
estimation was drawn from a peripheral vein within 10 minutes of TcB measurement.

Eighty nine (59.3%) subjects were male and 61(40.7%) females. One hundred and twenty nine
subjects (86%) were of 37-39 weeks gestational age while 56 (37.3%) presented in the clinic
after 48hrs of life with neonatal jaundice. The difference between the bilirubin values measured
with TcB and TSB was low, with 104 subjects (69.3%) having a difference that was less than
0.9mg/dl. Over 83% of the subjects had TcB values that were higher than TSB values and the
percentage of subjects with bilirubin values TSB values >12mg/dl was 45.2% compared with
56.8% obtained by TcB. In the present study bilirubin levels measured with the JM-103 show
a good agreement with TSB levels in the study subjects. The analysis of covariance indicated
that none of the neonatal variables measured was a significant contributor to the TcB

correlation error with TSB. Therefore, the mean error of TcB compared with the TSB level was
independent of gender, gestational age, age at presentation or birth weight. Similarly, a
correlation of TcB with TSB using the Pearson’s correlation coefficient showed a positive
correlation (r= 0.924) between TcB and TSB scores.
The measured bias by the Bland and Altman method between TSB and TcB showed that the
mean difference between the two assays was 0.97 mg/dl (95% CI: 0.74–1.21). The imprecision
was in the two measurements was ±2.96 mg/dl. A comparison of the correlation values obtained
at the three body sites obtained the best correlation at the forehead (r= 0.928). The excellent
correlation of TcB with TSB obtained from this study is encouraging since the Konica Minolta
JM-103 does not require replacement tips, which are associated with a high maintenance cost
after the initial purchase of the device. It is envisaged that further researches will be carried out
in black neonates and that the use of the JM-103 will be widely adopted as a screening tool in
Nigeria.