Advances in pediatric care have led to a growing population of adults with spina bifida (SB), in whom long-term management of lower urinary tract (LUT) and bowel dysfunction is essential. Both systems share central and peripheral neural pathways, suggesting that dysfunction in one may be reflected in the other. We hypothesized that bladder emptying strategy, specifically clean intermittent catheterization (CIC) versus spontaneous voiding, would be associated with differences in both urinary parameters and bowel function. The aim of this study was to evaluate the relationship between LUT and bowel dysfunction in adults with SB, with particular focus on the interplay between bladder management method and bowel symptoms, intestinal sensation, and management strategies.

We performed a retrospective, single-centre cohort study including adult SB patients attending a multidisciplinary clinic at a university referral hospital. Data from 79 patients were screened, of whom 57 met inclusion criteria (exclusive use of either spontaneous voiding or CIC, no history of augmentation cystoplasty).

Clinical data were obtained from standardized intake assessments. Bowel function was evaluated through structured history taking, including constipation, fecal incontinence, intestinal sensation, and use of bowel management techniques (laxatives, colonic irrigation, or both). Bladder function was assessed using a two-day bladder diary, from which voiding frequency and minimum and maximum voided volumes were derived.

Patients were stratified into two groups based on bladder emptying method: spontaneous voiding (n=27) and CIC (n=30). Statistical analyses included chi-square tests for categorical variables and independent t-tests for continuous variables, with significance set at p≤0.05.

CIC users demonstrated a significantly higher prevalence of constipation compared with spontaneous voiders (76.7% vs. 37.0%, p=0.003). Reduced intestinal sensation was also more common in the CIC group (50.0% vs. 14.8%, p=0.001).

Use of bowel management strategies differed markedly between groups. Patients using CIC more frequently required interventions such as laxatives, colonic irrigation, or combined approaches (all p=0.001), whereas the majority of spontaneous voiders did not use structured bowel management.

Regarding bladder diary parameters, minimum and maximum voided volumes were significantly higher in the CIC group (approximately 300 mL vs. 185 mL, p=0.008; and 845 mL vs. 610 mL, p=0.005, respectively). In contrast, no significant difference was observed in voiding frequency between groups (p=0.275).

The associations observed are most consistent with a shared neurogenic substrate affecting both bladder and bowel function. Patients using CIC likely represent a subgroup with more extensive neurological impairment, reflected in diminished intestinal sensation and increased reliance on bowel management strategies. Importantly, the substantially larger minimum and maximum bladder volumes observed in this group suggest delayed or insufficiently frequent emptying, placing patients at risk of chronic bladder overdistension. Over time, this may contribute to structural and functional deterioration of the bladder.

Bladder and bowel dysfunction in adults with spina bifida are closely interconnected and reflect shared neurogenic mechanisms. Patients using CIC exhibit both increased bowel dysfunction and bladder volumes exceeding desirable ranges, suggesting a risk of chronic bladder overdistension. These findings underscore the need for integrated management strategies that combine structured bowel care with active monitoring and optimization of catheterization regimens to prevent long-term bladder damage.