Crotch protection. In the interyagic fold, between the coccyx and the anus, it is necessary to put a cotton wool or gauze “ear”, so that the antiseptic does not burn the perineum, especially the mucous membrane of the anus (it is near).
Treatment of the skin with an antiseptic should be careful (so that it does not cover the perineum), but reliable (the skin here contains many micro organisms). This treatment should be wide enough to encompass all landmarks (including both spinae iliacae posteriores superiores), which will have to be palpated before the injection.
First of all, you should reliably determine the median line. The first landmark lumbar and sacral spinous processes. If they are hard to find, you can feel the tip of the coccyx with your left index finger and move cranially 4-5 cm (in an adult), where the fingertip will be in the hole above the cruciform orifice, just between the sacral horns that you need to feel, slightly moving your finger left and right. Strong pressure on the horns is not necessary — the patient will be hurt. These horn should be almost the same size. If one of them is much smaller, it is possible that this is not the horn, the asympulum of the lower cuspidal ridge. That is why the main thing is to clearly define the median line. An additional, confirmatory, landmark is that both spinae iliacae posteriores superiores form a regular, equilateral, triangle with the sacral foramen. As soon as the tip of the left index finger is above the sacral opening, it is not necessary to move the finger, so as not to “lose” this place. It is here, between the tips of the cornua sacralia, that a thin needle is injected to anesthetize the skin (“lemon peel”) or they simply pierce the skin with a sharp needle.
Anesthesia of the skin (if a puncture with a thick needle is planned) must be reliable (the place is rather painful), but not too abundant, so that a large volume of the injected solution does not interfere with re-palpation of the landmarks. When performing infiltration anesthesia under the skin, one can “feel” the sacrum-coccygeal membrane and the entrance to the sacral canal with the tip of the same thin needle, in order not to make it a thicker needle.
Puncture of the skin with a thick needle (for example, a Dufot needle), before the introduction of a thick and blunt needle for caudal anesthesia, will not only facilitate its introduction, but also prevent a piece of skin always infected in this area from entering its tip into the epidural space. However, in most cases, a one-time anesthesia (not a thick and not a blunt needle) all this is superfluous.