The human rectal temperature is normally around 37-37.5 ° C and tends to increase in relation to the depth at which it is measured. It is therefore advisable to measure the rectal temperature at a standard depth (about 5 cm in the adult), especially in the case of repeated tests.
Once inserted, the thermometer must be kept in place for at least two or three minutes. Before proceeding with the measurement, however, it is a good rule that the subject is kept at rest for at least half an hour.
Among all, the rectal temperature is the best representative of the central or basal temperature, while the values measured in the oral and axillary areas are respectively lower by about 0.5 / 1 ° C. The rectal temperature is in fact less susceptible to changes due to external factors (such as the ambient temperature), although it is still subject to the typical circadian fluctuations (higher in the late afternoon), to muscular activity, to emotional stress and to the phase of the menstrual cycle ( increases by half a degree in the period between ovulation and the beginning of menstruation).
To relate the rectal temperature to the axillary temperature it is necessary to subtract 5-10 dashes (half a degree / one degree) and vice versa. In practice, therefore, a value of 38 ° C at rectal level corresponds to about 37-37.5 ° C of axillary temperature.
Rectal temperature measurement techniques
How to measure the rectal temperature in the child
- Clean the thermometer with soap and water, then rub it with a towel soaked in alcohol or disinfectant and rinse it.
- The thermometer (of the small ones for children), should be held firmly between the index and the middle finger. If an old mercury model is used (not recommended), it will be shaken with energy until the column has fallen below 34 ° C.
If you use the digital thermometer, this must be turned on before using it.
- Spread the baby supine (belly up) in a rigid plane (changing mat or bed). With the left hand grasp the ankles of the little one and raise the legs, as shown in the first figure on the left.
- Immerse the bulb of the thermometer in the oil or in the Vaseline with your right hand, then gently introduce only the bulb (not more than 1.5 / 2 cm) into the child's rectum.
- Tighten the buttocks of the child holding them firmly and wait two or three minutes.
- Once the necessary time has elapsed, read the measured rectal temperature value on the thermometer.
Among all the possible detection sites, the measurement of rectal temperature - by virtue of the greater degree of adherence to the basal temperature - is the most reliable, especially in infants and young children. Measuring temperature below the armpit gives more reliable results from the age of four or five. Furthermore, in children it is strongly recommended to use digital thermometers to replace older models in glass, containing mercury and as such rather dangerous in the event of accidental breakage.
The rectal temperature measurement must be performed with the child lying on its side and with the thighs flexed at right angles (central figure), even if other positions are possible. The thermometer should be inserted into the anus gently, avoiding the maneuver in the presence of bleeding or other contraindications reported by the pediatrician. The thermometer must be previously washed under lukewarm running water with a little soap, then rubbed with gauze soaked in alcohol or disinfectant and rinsed again; the same operation will be repeated at the end of the measurement. Before insertion, the bulb should be sprinkled with a special lubricant that can be purchased in pharmacies (vaseline). The maneuver will have to be performed with particular delicacy, making it penetrate for no more than a couple of centimeters and without forcing the maneuver if resistance is encountered.
Regarding the correct interpretation of rectal temperature in children, it is good to rely on what the pediatrician has reported. In general, however:
a rectal temperature value greater than 38 ° C can be considered febrile.
When to contact the pediatrician
Observe the following characteristics beforehand: - is the child pale - is he / she lively? Do you have an appetite or do not feel like eating? do you want to play? are you crying all the time? is it much calmer than usual? Do you breathe with difficulty? Do you have a stuffy nose, cough, ear pain and / or difficulty moving your head? Is there vomiting or diarrhea? What is your rectal temperature?
Warning signs : the child is very irritable, cries continuously and is difficult to console; he is very sleepy and it is hard to wake him up; he moves his head and neck with difficulty; violently shakes his arms or legs, remaining rigid or abandoned (convulsions); has red or dark spots on the skin; has more than 50 breaths per minute (between 3 and 12 months of life) or more than 40 breaths per minute (after 13 months of life); he has severe pain in his belly.
In the first three months of life, temperatures even slightly above the norm deserve careful medical evaluation, since they could be associated with a severe infection. From three months to three years of life, all cases of rectal temperature above 39 ° C should be brought to the attention of the pediatrician. In these cases, the temperature level (ie a more or less high fever) is not sufficient to make the extent of the problem clear. In fact, fever is not a disease in itself, but a reaction of the body to the attack of bacteria or viruses. For this reason it is necessary first of all to observe the child and realize how he is; in addition to the rectal temperature, characteristics such as appearance, agitation, suffering state, the type of rest that it is able to have and the presence of respiratory difficulties should therefore be evaluated. These signs will help the pediatrician to better interpret the condition and decide to plan the visit at the most appropriate time.
