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Anorectal manometry was performed in 48 Japanese children with Hirschsprung's disease and 61 normal children. The resting pressure of the rectum and anal canal was not significantly different between these groups of subjects. The frequency of rhythmical contractions of the anal canal of patients was significantly lower than for the normal subjects, but the frequencies overlapped considerably. Therefore, the frequency is an inadequate indicator for identifying these patients. Conventional manometry elicited a distinct rectoanal relaxation reflex from 90% of the normal children, and the rate increased to 98% when indistinct reflexes were regarded as positive. Indistinct reflexes often occur in neonates, possibly because the constriction of the anal canal is weak. However, when prostaglandin F2 alpha was intravenously administered during the examination, all ambiguous reflexes became distinct. Of patients with Hirschsprung's disease, 4% had a distinct reflex and 19% an atypical one. Most of the atypical reflexes were regarded as being artifacts and were mostly attributed to distension by a balloon. In these patients, the reflex was abolished in case of examination with electric stimulation or stimulation with cold water, procedures which do not dilate the rectum. Moreover these atypical reflexes did not fit the criteria for the normal rectoanal relaxation reflex prepared by the Japan Study Group of Pediatric Intestinal Manometry. The use of electric stimulation, cold water, or intravenously administered prostaglandin F2 alpha improves reliability of the conventional anorectal manometry. A clear and accurate definition of the normal reflex should aid in excluding the atypical reflex.

Bowel function after surgery for anorectal malformation was assessed by Kelly's score in 101 children over 3 years of age. Seventy-two were examined using anorectal manometry. In the "good" group, resting pressure of the anal canal was as high as in the normal children, and the frequency of contraction waves in the anal canal was the same as in the normal children. Recto-anal reflex was recognized in about three fourths of the "good" group. On the other hand, in the "poor" group resting pressure was low, in only one were contraction waves evident and in none was there a recto-anal reflex. The findings of the anorectal manometry placed the "fair" group between the "good" and the "poor" groups. The clear contraction waves of the anal canal or the clear recto-anal reflex related to a resting pressure in the anal canal of over 20 cmH2O. This high pressure in the anal canal is important for good and continence, and depends on a precise pull-through of the rectum into the puborectalis muscle.

The intraluminal pressure of the rectum and anal canal were measured in patients with Hirschsprung's disease before and after Ikeda's Z-shaped anastomosis, and the association of the pressure with postoperative capability of fecal continence was assessed. Radical operation did not alter rectal pressure but did decrease anal-canal pressure. Rhythmical anal contractions increased in frequency until a normal level was attained. The rectoanal relaxation reflex became distinct with time, and 45% of patients eventually attained the reflex after operation. In patients who postoperatively attained satisfactory fecal continence or, at least, only soiling, resting pressure in the anorectum and the frequency of rhythmical anal-canal contractions were similar to those for normal children. The rectoanal relaxation reflex was induced in 58% of the former and 27% of the latter. In patients with postoperative constipation, the intraluminal resting pressure of the anorectum was elevated without the relaxation reflex response. In patients with incontinence, the pressure of the anal canal was low, without a reflex response. These findings indicate that the high and low values of the resting pressure of the anal canal are responsible for constipation and incontinence, respectively, and that the presence of rectoanal relaxation reflex may represent one aspect of a normal defecation function.

Anorectal manometry was performed on mongrel dogs given various drugs in attempts to determine the effect of the drugs on rectoanal inhibitory reflex. Anal canal pressure was significantly increased by the administration of neostigmine and noradrenaline and significantly lowered by isoproterenol. The amplitude of the rectoanal inhibitory reflex was increased by the administration of neostigmine and prostaglandinF2 alpha (PGF2 alpha), decreased by atropine but was little affected by either noradrenaline or isoproterenol. These results suggested that cholinergic neurons have an excitatory effect both on the anal canal pressure and the rectoanal inhibitory reflex, while adrenergic alpha and beta receptors have little effect on the rectoanal inhibitory reflex. PGF2 alpha was though to increase the motor activity of the anal sphincter and facilitate the rectoanal inhibitory reflex. Neostigmine and PGF2 alpha may aid in clarifying rectoanal inhibitory reflexes in neonates or postoperative children with rectoanal diseases.

To improve the accuracy of diagnosis of Hirschsprung's disease by means of anorectal manometry, prostaglandin F2 alpha (PGF2 alpha) and scopolamine-N-butylbromide (Buscopan) were used. Normal rectoanal reflex was facilitated by PGF2 alpha in 6 out of 7 children and was abolished or markedly inhibited in 12 out of 13, when Buscopan was given. Obscure rectoanal reflexes in 7 normal neonates were clarified following the administration of PGF2 alpha. On the other hand, atypical rectoanal reflexes observed in 7 children with Hirschsprung's disease were unchanged with either PGF2 alpha or Buscopan. Therefore the use of PGF2 alpha or Buscopan facilitates the manometric diagnosis of Hirschsprung's disease. In 9 postoperative children with Hirschsprung's disease the reflexes were obscure. Five of these 9 reflexes became clear after the administration of PGF2 alpha and 4 remained unchanged. As the normal rectoanal reflex was enhanced by PGF2 alpha, the obscure reflex seen in the postoperative period can be positive or negative, using PGF2 alpha.