Balloon defecation as a predictor of outcome in children with functional constipation and encopresis

Objective: To evaluate whether the ability to defecate a rectal balloon might predict 12-month recovery in children with functional constipation and encopresis. Methods: We evaluated the ability to defecate within 5 minutes a 100 mi water-filled rectal balloon by 20 healthy children and 139 children with functional constipation and encopresis. Results: All healthy children and only 47% of the patients were able to defecate the balloon. Twelve months after the start of treatment, 51% of patients able to and 34% of patients unable to defecate the balloon had recovered (p < 0.03). Logistic regression revealed that the ability to defecate the balloon and a history of secondary encopresis were related to recovery (p < 0.04). Patients who were unable to defecate the balloon or who did not recover had significantly more impairment in anorectal functions than those who were able to defecate the balloon or who did recover. The ability of the balloon defecation test to predict recovery had a sensitivity of 57%, a specificity of 60%, a positive predictive value of 0.51, and a negative predictive value of 0.66. Conclusion: Children with functional constipation and encopresis who were able to defecate the rectal balloon were twice as likely to recover. Even though there was a clinically significant difference in the recovery rates between patients who could and those who could not defecate the balloon, calculation of predictive values showed that the balloon defecation test could not reliably predict recovery.