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While doing a discharge check on a 3 day old baby, a paediatric SHO notices mild jaundice and prepares to perform a serum bilirubin estimation (SBR). She explains this to the mother, who breaks into tears and asks the SHO if there was any way she could check the level of jaundice without doing a blood test. The SHO discusses this with the neonatal consultant who mentions “We used to have a transcutaneous bilirubinometer when I was an SHO, but we stopped using it because it was inaccurate”.
A more sympathetic registrar gives you a recent review article1 on jaundice which indicates that the older generation bilirubinometers were shown to be inaccurate for clinical use; however, a newer version, the “SpectRx Bilicheck” may be more reliable. Bilicheck (BC) uses multiple wavelengths of light, and the manufacturer claims that the monitor is unaffected by skin pigmentation and other interfering factors.
You wonder if the Bilicheck could be safely used as a screening test for jaundice on the postnatal wards.
Structured clinical question
In term or near term healthy newborn babies [population] can transcutaneous bilirubinometry [test] when compared with serum bilirubin estimation [gold standard] accurately identify all cases of significant jaundice (i.e. >250 μmol/l)?
Search strategy and outcome
We searched PubMed under clinical queries and diagnosis using keyword “Bilicheck”, which identified three studies, all of which were of good quality. See table 2.
We intended to use transcutaneous assessment on the postnatal ward as a screening test. It was important that the Bilicheck would not miss any significant jaundice. We arbitrarily chose 250 μmol/l (a level below which an intervention would be unlikely in term or near term babies after 24 hours). We wanted to determine if Bilicheck had a high sensitivity at this SBR level, so that babies would not need a blood test if Bilicheck value was less than 250 μmol/l. Bilirubin values were converted to SI units (μmol/l) (1 mg = 17.1 μmol/l) for easiness of comparison.
The review is confined to three good quality studies identified following a basic PubMed search. The first two studies compared Bilicheck with the internationally accepted gold standard for bilirubin estimation2–4 (that is, high performance liquid chromatography) and found that it was at least as good as laboratory method.
Even though all studies showed good correlation between the Bilicheck readings and laboratory values, it was more important to establish that no cases of significant jaundice would be missed when it is used as a screening test.
Considering bilirubin levels of >250 μmol/l as significant jaundice, it appears that Bilicheck can be used to exclude significant jaundice and therefore reduce the number of serum bilirubin estimations. It is unlikely that the sensitivity of Bilicheck would be 100% in clinical practice; however, by using a low cut off for estimating serum bilirubin, the false negatives would be still well below the levels associated with neurotoxicity. Bilicheck has been shown to have similar efficacy in a wide range of ethnic groups.
Since we wanted to examine the use of Bilicheck in postnatal wards, this review is confined to only term and near term babies. There are insufficient data to support the routine use of Bilicheck on babies receiving phototherapy at present.
CLINICAL BOTTOM LINE
In healthy term and near term newborn babies, “Bilicheck” can be safely used as a screening test for jaundice to avoid blood sampling.
We are grateful to Wilf Kelsall for the kind suggestions and proofreading the manuscript.