Body Temperature Measurement Sites: Accuracy, Indications, and Technique

Core temperature (blood in hypothalamus) is the gold standard. Peripheral sites approximate it with varying accuracy.

Common Sites

Site	Method	Normal Range	Accuracy vs. Core	Best For
Oral (sublingual)	Digital, 30–60s	36.1–37.5°C (97–99.5°F)	Good (±0.3–0.5°C)	Adults, cooperative children >5y
Rectal	Digital, 10–20s	36.6–38.0°C (97.9–100.4°F)	Gold standard peripheral	Infants <3m, unconscious, critical care
Axillary	Digital, 30–60s	35.5–37.0°C (95.9–98.6°F)	Lower (±0.5–1.0°C); lag	Screening, uncooperative, safety
Tympanic	Infrared, 1–2s	36.1–37.5°C	Good if technique perfect	Quick screen, children >6m
Temporal Artery	Infrared scan	36.1–37.5°C	Variable; technique-sensitive	Non-invasive screen, all ages

Less Common Sites

• Esophageal/nasopharyngeal (OR/ICU core).
• Bladder (Foley probe).
• Skin (zero-heat-flux).

Site Selection Factors

• Age/cooperation
• Required accuracy (diagnosis vs. screening)
• Equipment availability
• Patient comfort/safety
• Clinical context (surgery, fever workup, hypothermia)

Document site used. Trends > single values. Rectal remains reference for infants; oral for adults.