Retention test in sacral nerve stimulation for fecal incontinence.

Introduction: Sacral nerve stimulation has become an established treatment for patients with fecal incontinence. However, the mechanism of its action remains obscure. We aim to assess whether sacral nerve stimulation improves patients' ability to retain rectal content.
Methods: Patients who had been treated successfully with sacral nerve stimulation underwent four retention tests during which the stimulator was turned either on or off. Both the patients and investigators were blinded to the status of the stimulator. The retention test results were assessed for interassessment agreement and for any differences between the on and off phases. Wexner scores, anorectal physiology tests, and patients' perceptions of stimulator settings were also recorded.
Results: Nineteen patients (16 women; mean age, 57.5 years) took part in the study. Retention tests showed moderate interassessment agreement (weighted Cohen's kappa index, 0.45). There were no sharp differences in retained volume between the stimulator's on and off phases (median 50 (range, 0-300) mL vs. 50 (range, 0-300) mL; P = 0.85).
Conclusion: Sacral nerve stimulation does not alter patients' ability to retain rectal content. Further studies are needed to investigate the mechanism of sacral nerve stimulation.