Rectal diameter assessment in enuretic children—exploring the association between constipation and bladder function

Objectives: Detrusor overactivity and constipation often co-exist in children with enuresis. Constipation is known to be linked to detrusor overactivity. The voiding chart is the best non-invasive way to investigate bladder function, whereas the ultrasonographical detection of rectal dilatation is the best way to objectify constipation. We wanted to investigate a possible relationship between the rectal diameter and voiding chart data in enuretic children. Methods: Children with therapy-resistant enuresis were retrospectively evaluated. All had completed a voiding chart for at least 48 h. The rectal diameter was assessed ultrasonographically. The cutoff for rectal dilatation was set at 30 mm. Results: We evaluated 74 patients (12 girls) aged 10.2 ± 2.8 years, 35 of whom had rectal dilatation. No significant differences in voiding chart parameters were found between children with normal versus dilated rectum. Neither did urgency or a history of daytime incontinence differ between the groups. Boys were more likely to have rectal dilatation than girls (p = 0.02). Conclusions: The absence of differences regarding voiding chart data may be explained as two mechanisms neutralizing each other: behavioral factors may make the constipated children void seldom and with large volumes, whereas detrusor overactivity caused by rectal compression of the bladder may have the opposite effect. Another option may be that the voiding chart is too blunt an instrument to detect detrusor overactivity. Constipation, and thus presumably bladder dysfunction, seems to be more important in enuretic boys than girls.