The development of anorectal continence and its significance in the diagnosiso of Hirschsprung's disease.

The development of the anorectal continence reaction was studied in a series of 138 electromanometric recordings performed in 62 newborn and six premature infants. Forty-five babies were observed in a longitudinal study. In 11% an internal sphincter relaxation was observed at the time of birth. The same reflex was present in about 50% after the third day and in all infants after the 12th day of life. The development of a rectal continence reaction depends on an intact internal sphincter relaxation. The puborectalis muscle, is fully functional at birth. On the basis of these findings electromanometric recordings can be used to exclude aganglionic megacolon as early as the first day of life. An absent internal sphincter relaxation reflex, is diagnostic only after the 12th day of life.