The effect of anorectal manometry on the outcome of treatment in severe childhood constipation: a randomized, controlled trial.

OBJECTIVE
Approximately 50% of constipated children contract rather than relax the external sphincter complex during a defecation attempt. Although biofeedback training (BF) is able to change this defecation behavior, there is no additional effect of BF to conventional treatment (CT) on clinical outcome compared with CT alone. It has been postulated that the absence of a significant difference between these 2 treatment options might be because of a therapeutic, "demystifying" effect of performing anorectal manometry in conventionally treated children, necessary to obtain basal manometric data. The objective of this prospective, controlled, randomized study was to evaluate the effect of CT with 2 anorectal manometry sessions compared with CT alone (dietary advice, diary, toilet training, oral laxatives, and enemas) on clinical outcome.


METHODS
A total of 212 constipated children (143 boys) who were visiting a referral pediatric gastroenterologic practice were randomized prospectively to CT alone (115 patients) or to CT combined with 2 manometry sessions (CTM; 97 patients). Patients were included in the study when they fulfilled at least 2 of the 4 following criteria: stool frequency fewer than 3 per week, 2 or more soiling and/or encopresis episodes per week, periodic passage of very large amounts of stool every 7 to 30 days, or a palpable rectal or abdominal fecal mass. CT comprises dietary advice, a daily diary, toilet training, and oral laxative treatment preceded by rectal disimpaction with enemas on 3 consecutive days. During both manometries, the child and the parent could watch the tracing on the computer screen. No explanation was given to either the child or the parents during the procedure. When the procedure was finished, the tracings were clarified. Successful treatment was defined as a defecation frequency of 3 or more per week and fewer than 1 soiling/encopresis episode per 2 weeks and no use of laxatives.


RESULTS
Only 4 and 2 children from the CT and CTM groups showed no soiling and/or encopresis, whereas 76% and 65%, respectively, reported the periodic passage of large stools. In 26% and 30% of the patients, a rectal scybalum was found on physical examination. The success rates at 6, 26, 52, and 104 weeks' follow-up were 4%, 24%, 32%, and 43% and 7%, 22%, 30%, and 35% in the CT and CTM group, respectively. No significant difference in success percentage was observed between the 2 groups at any time of follow-up with relative risks (CT/CTM) and 95% confidence intervals, respectively, of 0.55 (0.16-1.89), 1.13 (0.67-1.89), 1.07 (0.69-1.65), and 1.23 (0.81-1.85). A significant increase in defecation frequency was observed between the first (intake) and second visits, which was sustained at all subsequent visits and stages of follow-up in both groups (not significant). Also in relation to the first visit, a significant decrease in encopresis episodes was shown and a further slow but significant decrease at 52 weeks of follow-up in both groups. The manometric data obtained from the CTM group showed a low percentage of children with normal defecation dynamics, namely 28%, which (significantly) increased to 38% at the last manometry.


CONCLUSIONS
Anorectal manometry combined with CT compared with CT alone did not result in higher success rates in chronically constipated children. Therefore, anorectal manometry has no additional demystifying or educational effect on clinical outcome in chronically constipated children. This observation together with the observation in the current and previous studies that no correlation was found between (achievement of) normal defecation dynamics and success and that no relation was observed between volume of urge or critical volume and success leaves no diagnostic or therapeutic role for anorectal manometry in chronic constipated children, except its use as a diagnostic test to exclude Hirschsprung's disease. A simple CT is successful in 30% of severely constipated children who are referred to a tertiary hospital, underscoring the importance of long-lasting and adequate laxative treatment.