Six studies (n=386) were included in the review. These comprised five pre-test post-test case series (two in adults, n=75; three in children, n=300) and one post-test only case series (11 children).
In terms of quality, all studies were rated as level IV evidence (representing case series).
Studies in adults.
A study in 52 elderly patients undergoing individual pharmacological management for chronic constipation and LUTS found that alleviating constipation resulted in a significant decrease in post-void residual volume (85 to 30 mL, p<0.001) and improvements in urinary flow, number of weekly defecations, time taken up with toileting, incidence of symptoms of urgency and frequency, incidence of burning sensation during urination and number of bacteriurial events, self-reported quality-of-life measures and satisfaction with sexual activity treatment.
One study in 23 women attending a urogynaecology clinic found that participants reported their first desire to void occurred earlier when undergoing rectal distension using rectal balloon catheters than in the absence of a full rectum. Detrusor pressure was significantly increased in response to increases in detrusor pressure generated during balloon filling. However, data were not reported in the review.
Studies in children.
A study in 234 children attending an out-patient encopresis clinic that provided education to the child and parents as well as treatment reported that among the 52% of children reported as having their constipation relieved, no further symptoms of daytime incontinence were reported by 89% and night-time incontinence was reported as resolved by 63%. The study reported that all of the children who had been successfully treated for constipation were free of recurrent UTI at re-evaluation. However, all of the data were self-reported by parents or children.
A study of treatment with polyethylene glycol 3350 in 46 children with symptoms of dysfunctional elimination compared urinary symptoms of children who had their constipation successfully treated (n=36) with the symptoms of those children who remained constipated (n=10). Children in whom constipation was resolved had a significantly lower post-void residual (11.8% compared with 30.6%, p=0.01) and were significantly more likely to become dry or improved than those who remained constipated (p=0.045).
In a study of 20 children with voiding dysfunction (only 8 of whom had co-existing 'obstipation') undergoing a multifaceted individualised and noninvasive intervention for recurrent UTIs and 'obstipation' reported that 'obstipation' was alleviated in 5/8 children. However there were no differences in outcomes between children whose 'obstipation' was resolved and those who did not have 'obstipation'.
A post-test only study in 11 children with severe chronic constipation and LUTS undergoing colonic mamometry and urodynamics reported that all urinary symptoms persisted in all children, despite improvement in constipation.