The first neonatal examination should be carried out from the delivery room to assess: 1. Initial neonatal well- being; 2. Vital signs at birth; 3. Somatometry; 4. Complete physical examination; 5. Verify anorectal permeability and 6. Detect congenital malformations, including Anorectal Malformations. The Clinical Practice Guideline and the experts in Anorectal Malformations recommend detection by introducing a rectal thermometer through the anus with which, at the same time, the rectal temperature is taken. However, there is no real well-structured technique for such a procedure. In Mexico, Latin America, and in countries with limited resources, a large part of the personnel who care for newborns, including doctors, nurses, and students, take rectal temperatures "in their own way" SIC, unaware of "a technique" and the "true objective" of this procedure, generating detection failure and risk of injuring the distal digestive tract by carrying out the procedure empirically and by the incorrect use of thermometers to take the rectal temperature. This issue has not been addressed for more than three decades nor has the way of 1. Checking anorectal patency changed; 2. Detect anorectal malformations; 3. Take the rectal temperature in neonates and infants. For this reason, our objective is to publicize our "New Technique to Verify Permeability and Anorectal Malformations and take the rectal temperature in neonates and infants", with which we carry out these three actions with a single non-empirical procedure of a scientifically medical nature.