Anal tonometry in the neonatal period in mature and premature children.

Anal tonometry was performed during the first days of life in twelve premature and fourteen mature children without signs of gastrointestinal disease. A new tonometer with small dimensions was used. A pressure decrease of the internal anal sphincter after distension of the rectum could be demonstrated in all children examined and as early as two hours after birth. This was to be expected as the relaxation of the internal sphincter is part of the normal defecation reflex. Thus anal tonometry can be used in the early diagnosis of Hirschsprung's disease presumable already from the very first days of life.