Children with enuresis - are they more constipated than others?

The bowel-bladder interaction is well established, as is the fact that constipation can lead to daytime incontinence and/or recurrent urinary tract infections. However, the link between constipation and enuresis is less clear. The bowel's influence on enuresis is possibly important even though fecal disimpaction by itself will not make the child dry at night. Furthermore, parents and patients may be unaware of the child's constipation until the enuresis is evaluated. The same should apply to healthy children. The hypothesis that a full bowel affects bladder function appears to be logical; however, this may not be applicable in enuresis. A crucial question is if constipation is more common among children with enuresis than in the general population.

To evaluate the prevalence of constipation in children with enuresis as compared to children without bladder problems.

In this case-control study the former group was recruited from a pediatric clinic and the latter from the general population in the same geographic area. All children had their horizontal rectal diameter measured via abdominal ultrasound. Their bowel movements over two weeks and bladder function over two days were recorded at home.

We recruited 66 children with enuresis and 58 healthy controls. The ages ranged from 6 to 11 (mean 7.3 ± 1.3) years and 50 (40 %) of them were girls. The groups had no difference in rectal diameter (28.9 ± 7.7 vs 28.2 ± 10.1 mm, P = 0.672) and they had a similar prevalence of constipation according to the Rome IV criteria. The children with enuresis had fewer bowel movements per two weeks (11.2 ± 4.1 vs 14.8 ± 6.9, P < 0.001) than controls, but they had no more constipation symptoms. However, bladder diaries showed that children with enuresis had smaller voided volumes (87.1 ± 31.8 vs 127.5 ± 44.5 % of expected bladder capacity; P < 0.001) than controls.

We did not find support for constipation being more prevalent among children with enuresis than controls. But we did find decreased functional bladder capacity in patients with enuresis which may be an indirect sign of detrusor overactivity.