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Three Part Question

In [neonates] how accurate is [axillary thermometry] compared to [rectal thermometry] at accurately [measuring core body temperature]?

Clinical Scenario

A previously well, term 10 day old female neonate presents to the emergency department. Her parents say she feels like she is ‘burning up’ and is irritable. On initial inspection you agree that she looks unwell, her temperature as taken with a axillary thermometer is 37.7oC. She has no focus for her fever on examination. You would like to know how accurate axillary temperatures are and whether you should check the temperature using rectal thermometry.

Search Strategy

Using the Medline database: 1950- week 1 June 2010 via OVID.
Embase database: 1980- week 23 2010 via OVID
CinAHL: CINAHL plus: 1937- June 2010
[axillary thermometer$.mp OR axilla$ thermometers.mp. OR axilla temperature.mp] AND [rectal thermometer$.mp. OR rect$ thermometers.mp. OR rect$ temperature.mp.] AND [exp Body Temperature OR exp Fever OR febrile.mp OR exp Hot Temperature OR feve$.mp OR exp Skin Temperature OR exp Temperature] LIMIT to [english language and humans and ("all infant (birth to 23 months)" or "newborn infant (birth to 1 month)"]

Search Outcome

Medline: 5 papers, 3 of which were relevant
Embase: 3 papers, 0 additional relevant papers
CINAHL: 6 papers, 2 additional relevant papers

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Wilshaw R et al 1999 USA	39 infants (<90 days old) 5 of which were febrile, presenting in a community clinic.	Diagnostic study: axillary temperature was compared to rectal temperature (the gold standard).	sensitivity (temperature >37.6 degrees)	axillary= 80%	The study had a small un-justified sample size and was not blinded.
			sensitivity (temperature >38 degrees)	axillary= 100%
			specificity (temperature >37.6 degrees)	axillary= 21%
			specificity (temperature >38 degrees)	axillary= 58%
Yetman RJ et al 1993 USA	200 term well newborn infants (1-2 days old) in a well baby nursery in a teaching hospital	Observational study	mean temperature	axillary= 36.8 degrees (+/- 0.3 degrees), rectal= 37 degrees (+/- 0.4 degrees)
Haddadin RB et al 2007 Jordan	20 term neonates (less than 30 days old), consecutively selected from neonates presenting with a fever to the children's clinic or ED of the hospital.	Diagnostic study	sensitivity	axillary= 87.5%	The study had a small sample size and was not blinded.
			specificity	axillary= 100%
			mean temperature	axillary= 37.7 degrees (+/- 0.3 degrees), rectal= 38.1 degrees (+/- 0.3 degrees)
Haddock BJ et al 1996 USA	119 children (aged 7 days to 16 years) in a paediatric outpatients unit, 93 were afebrile and 26 were febrile.	Diagnostic study: comparing axillary temperature to rectal temperature (the gold standard)	sensitivity (temperature >37.8 degrees)	axillary= 19.2%	The study was not blinded and consisted of a wide age range with no median age given.
			<2 degree fahrenheit difference from rectal temperature	axillary= 33.6% (37.6% of afebrile and 19.2% of febrile cases)
			2 degree fahrenheit difference to rectal temperature	axillary= 4.2% (4.3% of afebrile and 3.8% of febrile cases)
			2.1-3 degree fahrenheit difference to rectal temperature	axillary= 37% (38.7% of afebrile and 30.8% of febrile cases)
			>3 degree fahrenheit difference to rectal temperature	axillary= 25.2% (19.4% of afebrile and 46.2% of febrile cases)
Brown PJ et al 1992 New Zealand	49 paired readings from 10 afebrile infants (ages 1-11 months) in a paediatric ward.	Observational study	mean temperature	axillary= 36.6 degrees (+/- 0.38 degrees), rectal= 37.5 degrees (+/- 0.25 degrees)	The study had a small sample size (although up to 7 measurements were taken from each individual) and the recruitment strategy was convenience sampling.

Comment(s)

A wide variety of literature exists on the topic of temperature taking methods, however the evidence is relatively limited when one seeks to specify neonatal temperature taking methods. Generally literature advocated the use of rectal thermometers, however, some accepted the popularity of axillary thermometers and found that they were suitable alternatives. Wilshaw et al's study found rectal temperatures to be more reliable but as axillary thermometers detected all fevers of 38 degrees or more, the study concluded that axillary thermometers could be used, instead of rectal ones, with caution. Yetman et al's study also supported the use of axillary thermometers as results were similar in most cases. However, in this study none of the participants were febrile. Haddock et al's study found a wide variability between axillary and rectal temperatures and the difference was greatest in febrile children therefore it concluded axillary temperatures to be unreliable, however this study involved a wide age range of participants so this may have affected results. Brown et al's study also agreed with Yetman in finding axillary temperatures neither consistent or reliable indicators of body temperature, this study however shared a similar weakness as it included older infants of up to 11 months old. Haddadin et al's paper is the only one which supports the use of axillary temperature as a reliable alternative to rectal temperature, as although the ability to detect fever by axillary thermometry is lower than rectal thermometry and there is a difference in mean temperature recordings the study concluded that axillary temperature is safer as avoids the risk of rectal perforation.

Clinical Bottom Line

Rectal thermometry is more accurate than axillary thermometry. However, most studies accept that in neonates less than 28 days old the difference between the two methods is not significant enough to use rectal temperatures routinely due to the risk of rectal perforation. However, if there is any doubt over an axillary thermometer reading or concern about the neonate then rectal thermometry should be used instead.

References

1. Wilshaw R, Backstrand R, Waid D et al A comparison of the use of tympanic, axillary and rectal thermometers in infants Journal of Pediatric Nursing 1999; 88-93
2. Yetman RJ, Coody DK, West SM et al Comparison of temperature measurements by an aural infrared thermometer with measurements by traditional rectal and axillary techniques Journal of Pediatrics 1993; 769-773
3. Haddadin RB and Shamo'on HI Study between axillary and rectal temperature measurements in children Eastern Mediterranean Health Journal 2007; 1060-1066
4. Haddock BJ, Merrow DL, Swanson MS The falling grace of axillary temperatures Pediatric Nursing 1996; 121-125
5. Brown PJ, Christmas BF, Ford RPK Taking an infant's temperature: axillary or rectal thermometer? New Zealand Medical Journal 1992; 309-311