How reliable is axillary temperature measurement?

AIM: To assess whether axillary temperature measurements reliably reflect oral/rectal temperature measurements.

METHODS: This observational study compared paired axillary-rectal and axillary-oral temperatures in a general paediatric ward with the participation of 225 children aged < or = 4 y and 112 children aged between 4 and 14 y.

RESULTS: Changes in oral/rectal and axillary temperatures correlated significantly (p < 0.0001). However, axillary temperature measurements were significantly lower than both oral (mean -0.56 degrees C, SD 0.76 degrees C) and rectal measurements (0.38 degrees C; SD 0.76 degrees C). Ninety-five percent of axillary measurements fell within a 2.5-3 degrees C range around respective paired oral/rectal measurements. The mean difference increased with increasing temperature, and was 0.4 degrees C at low body temperatures, and over 1 degree C with a fever of 39 degrees C. Neither seasonal fluctuations nor the amount of clothing worn influenced this difference.

CONCLUSION: Axillary temperatures in young children do not reliably reflect oral/rectal temperatures and should therefore be interpreted with caution.