Neuromodulation for Accidental Bowel Leakage

This study is a multi-center, randomized clinical trial of women with refractory accidental bowel leakage (ABL) symptoms who have failed to achieve satisfactory symptom control from 2 first-line treatments for ABL: supervised pelvic muscle training (PMT) and constipating medication. The purpose of this study is to compare percutaneous tibial nerve stimulation (PTNS) to a validated sham to determine if PTNS is effective for the treatment of fecal incontinence (FI) in women.

The investigators will test the null hypothesis that change from baseline in St. Mark's (Vaizey) score after 12 weeks of stimulation is not significantly different in women with symptomatic ABL receiving PTNS treatments compared to women receiving sham PTNS treatments.

The overarching goal of this randomized clinical trial is to determine if PTNS is more effective than sham PTNS for the treatment of FI in women after 12 weeks of treatment and 1 year after initiating treatment. This is a two-part trial with a Run-In Phase prior to randomization. The trial has the following primary aim:

To determine whether the change from baseline in St. Mark's (Vaizey) score in women with symptomatic ABL undergoing PTNS differs from sham after 12 weeks of stimulation.

Additional secondary aims include:

1. To compare changes from baseline in self-reported functional outcomes after 12 weekly stimulation sessions in both PTNS and sham groups in Part 1.
2. To determine whether symptom relief amongst study "responders" can be sustained for one year with maintenance treatments in Part II.
3. To determine the impact of completing a bowel diary and receiving education on FI on symptom severity.
4. To determine the ability of the PFDN ABL phone app bowel diary to detect changes from baseline in fecal incontinence episodes recorded to after 12 weeks of stimulation sessions.
5. To determine the association between St. Mark's score and both fat and fiber intake alone and in combination.

Eligibility Criteria:
Inclusion Criteria:

* Women ≥ 18 years of age
* FI symptoms ≥ 3 months
* Baseline St. Mark's score of ≥ 12
* Attended ≥ 2 supervised PMT for ABL
* Intolerance, unwillingness, or inadequate response to constipating medications
* Current negative colon cancer screening based on the USPSTF's recommendation for colorectal cancer screening (2016)

Exclusion Criteria:

* Previous PTNS treatment
* History of uncontrolled diarrhea in the past 3 months (usual or most common stool type over the preceding 3 months of 7 on the Bristol Stool Form Scale)
* History of severe constipation in the past 3 months (usual or most common stool type over the preceding 3 months of 1 on the Bristol Stool Form Scale)
* History of inflammatory bowel disease (includes Crohn's disease and ulcerative colitis, but does not include irritable bowel disease)
* Unrepaired rectovaginal fistula/chronic 4th degree laceration
* Full thickness rectal prolapse
* History of congenital anorectal malformation
* History of bowel resection surgery for any indication
* Minor anal procedures within 6 months for treatment of ABL (injection of bulking agent or radiofrequency energy) or ligation of hemorrhoids
* Prior pelvic or abdominal radiation
* Diagnosis of cancer of the descending colon or anus
* Diagnosis of cancer in the region where the PTNS or sham needles or surface electrodes would be placed
* Pacemaker, implantable defibrillator
* Current use of Interstim sacral nerve stimulator or TENS in the pelvic region, back, or legs
* Clinically significant neurological disorders known to affect anal continence
* Coagulopathy
* Severe peripheral edema preventing accurate placement of PTNS needles
* Chronic swollen, infected, inflamed skin or skin eruptions (e.g., phlebitis, thrombophlebitis, varicose veins) in the region where the PTNS or sham needles or surface electrodes would be placed
* Metal implant in foot/toes near TENS electrode location
* Marked sensory deficit (numbness) of feet or ankles in the region where the PTNS or sham needles or surface electrodes would be placed
* Childbirth within the last 3 months
* Pregnant or planning to become pregnant during the study duration 1 year; a urine pregnancy test will be performed and must be negative by the first intervention visit if the participant is of childbearing potential
* Unwilling to use acceptable form of contraceptive if the participant is of childbearing potential
* Participation in another intervention trial impacting bowel function
* Inability to provide informed consent, complete questionnaires independently, or to attend intervention sessions
* Unable or unwilling to complete the bowel diary in Run-In Phase (valid diary defined as data from ≥ 10 of 14 days with minimum of 3 consecutive days per week)
* Unwilling to download bowel diary app onto smartphone if the participant owns a smartphone
* Visual impairment prohibiting reading the paper diary, the smart phone screen
* Unable to speak, read, or write in English or Spanish at a basic level