Safety and efficacy of low-volume transanal irrigation in adults with bowel dysfunction: a prospective multicenter study

Technical Summary: Safety and Efficacy of Low-Volume Transanal Irrigation in Adults with Bowel Dysfunction

Problem Statement
Fecal incontinence (FI) and chronic constipation (CC) are prevalent bowel disorders that significantly impair quality of life (QoL) and psychosocial well-being. While conventional management includes dietary modification, pharmacotherapy, and pelvic floor rehabilitation, a substantial proportion of patients, particularly those with long-standing disease or pelvic floor dysfunction, experience persistent symptoms and dissatisfaction with bowel routines. Transanal irrigation (TAI) is an established minimally invasive therapy for these conditions. However, while high-volume TAI systems have extensive evidence support, data regarding low-volume TAI systems (specifically those instilling up to 185 mL) remain limited, particularly within non-neurogenic populations. There is a need for clinical evidence to validate the efficacy, safety, and patient satisfaction of low-volume TAI for adults with functional bowel disorders.

Methodology
This study was a prospective, multicenter, single-arm observational clinical investigation conducted across two Swedish clinical sites (Sahlgrenska University Hospital and Skåne University Hospital).

• Participants: 40 adult patients (median age 66; 92% female) with FI and/or defecatory disorders persisting for ≥6 months were enrolled. The cohort was predominantly non-neurological (80%), with primary symptoms including FI (65%), Outlet Defecation Syndrome (ODS) (25%), and chronic constipation (10%).
• Intervention: Patients were treated with the Navina™ Mini, a low-volume TAI device designed to instill up to 185 mL of water into the rectum via a single-use cone. Treatment duration was 4 weeks. Participants received standardized training and were instructed to perform the procedure daily or on alternate days based on individual response.
• Study Design: The study utilized a "per-protocol" population (n=38) for efficacy analysis and an "intention-to-treat" population (n=40) for safety analysis.
• Endpoints:
  • Primary: Overall patient satisfaction assessed via a study-specific 5-point PRO scale (0 = Not at all satisfied to 4 = Very Satisfied).
  • Secondary: Changes in validated symptom scores (Wexner FI Score, Cleveland Clinic Constipation Score [CCCS], and Renzi Obstructed Defecation Score), ease of use, treatment adherence, and safety (adverse events).
• Statistical Analysis: Changes over time were analyzed using the Wilcoxon signed-rank test, with a two-sided p-value < 0.05 considered statistically significant.

Key Results

• Patient Satisfaction: There was a statistically significant increase in patient satisfaction. At baseline, only 8% of patients reported being satisfied or very satisfied with prior bowel management. After 4 weeks of low-volume TAI, 81% of patients reported being satisfied or very satisfied (p < 0.0001).
• Symptom Improvement: Significant improvements were observed in specific pathophysiological domains:
  • Accidental fecal leakage (Wexner score; p = 0.0027).
  • Excessive straining (Renzi score; p = 0.0356).
  • Vaginal/perineal pressure (Renzi score; p = 0.0029).
  • Sensation of incomplete evacuation (Renzi score; p = 0.0229).
  • Note: Global constipation scores (CCCS) showed numerical improvement but did not reach statistical significance (p = 0.0912).
• Usability and Adherence: Device handling was rated as "easy" or "very easy" across all steps (77–100% of participants). Treatment adherence was high, with 74% of subjects using the device more than three times per week. Post-study, 84% of participants expressed a desire to continue treatment.
• Safety: Four mild and transient adverse events were reported; none were serious or device-related. Three device deficiencies were recorded, none of which resulted in adverse events.

Significance and Claims
The authors conclude that low-volume TAI using the Navina™ Mini is a safe, well-tolerated, and effective treatment for adults with fecal incontinence and defecatory disorders, particularly those with predominant rectal evacuation dysfunction.

The study claims that the high patient satisfaction and ease of use support the role of low-volume TAI as a valuable option within phenotype-directed, individualized bowel management. The results suggest that low-volume irrigation is particularly suited for patients with distal bowel dysfunction (such as ODS and FI), where the mechanism relies on rectal distension and reflex evacuation rather than proximal colonic washout. The authors emphasize that this study contributes to the limited evidence base for low-volume TAI in non-neurogenic populations, reinforcing a treatment approach where irrigation volume is tailored to the specific underlying pathophysiology.

Limitations Acknowledged
The paper modestly notes that the uncontrolled design limits the ability to attribute effects solely to the intervention, as concomitant therapies and increased clinical attention may be confounding factors. Additionally, the relatively short 4-week follow-up precludes assessment of long-term efficacy, and the modest, predominantly female sample size may limit generalizability.