Bedwetting can be due to undiagnosed constipation

Reporting online in the journal Urology, researchers found that 30 children and adolescents who sought treatment for bedwetting all had large amounts of stool in their rectums, despite the majority having normal bowel habits. After treatment with laxative therapy, 25 of the children (83 percent) were cured of bedwetting within three months.

"Having too much stool in the rectum reduces bladder capacity," said lead author Steve J. Hodges, M.D., assistant professor of urology at Wake Forest Baptist. "Our study showed that a large percentage of these children were cured of nighttime wetting after laxative therapy. Parents try all sorts of things to treat bedwetting -- from alarms to restricting liquids. In many children, the reason they don't work is that constipation is the problem."

Hodges said the link between bedwetting and excess stool in the rectum, which is the lower five to six inches of the intestine, was first reported in 1986. However, he said the finding did not lead to a dramatic change in clinical practice, perhaps because the definition of constipation is not standardized or uniformly understood by all physicians and lay people.

"The definition for constipation is confusing and children and their parents often aren't aware the child is constipated," said Hodges. "In our study, X-rays revealed that all the children had excess stool in their rectums that could interfere with normal bladder function. However, only three of the children described bowel habits consistent with constipation."

Hodges explained that guidelines of the International Children's Continence Society recommend asking children and their parents if the child's bowel movements occur irregularly (less often than every other day) and if the stool consistency is hard.

"These questions focus on functional constipation and cannot help identify children with rectums that are enlarged and interfering with bladder capacity," said Hodges. "The kind of constipation associated with bedwetting occurs when children put off going to the bathroom. This causes stool to back up and their bowels to never be fully emptied. We believe that treating this condition can cure bedwetting."

Children in the study ranged from 5 to 15 years old. The constipated children were treated with an initial bowel cleanout using polyethylene glycol (Miralax®), which softens the stools by causing them to retain water. In children whose rectums remained enlarged after this therapy, enemas or stimulant laxatives were used.

Hodges cautioned that any medical therapy for bedwetting should be overseen by a physician.

The study used abdominal X-rays to identify the children with excess stool in their rectums. Hodges and radiologists at Wake Forest Baptist developed a special diagnostic method that involves measuring rectal size on the X-ray. He said rectal ultrasound could also be used for diagnosis.

"The importance of diagnosing this condition cannot be overstated," Hodges said. "When it is missed, children may be subjected to unnecessary surgery and the side effects of medications. We challenge physicians considering medications or surgery as a treatment for bedwetting to obtain an X-ray or ultrasound first."

The study involved reviewing the charts of 30 consecutive patients treated for bedwetting. The authors cautioned that some cases may have improved on their own over time. They said a more accurate measure of the treatment's success would be to randomly assign constipated children to laxative therapy or an inactive therapy, an approach that would identify true response from cases that would resolve over time.

Hodges' co-author on the research is Evelyn Y. Anthony, MD, a radiologist at Wake Forest Baptist.