This is a prospective study evaluating the effect of a treatment method of sacral neuromodulation (SNM), the use of which is approved and recommended for the treatment of both faecal incontinence (FI) and urinary incontinence (UI). A new aspect of the study is monitoring the effect of SNM in patients with both types of incontinence (faecal and urinary) occurring simultaneously. The study will use diagnostic methods and procedures that are part of the usual examination algorithm. The study will not impose any burden on patients beyond the scope of routine examination and treatment procedures.

Faecal incontinence (FI) is defined as the involuntary loss of solid or liquid stool in patients. Incontinence harms the patient psychologically, socially and medically. FI is associated with an increased incidence of various skin conditions and inflammatory diseases, including multiple urinary tract infections.

Treatment of FI usually begins with non-invasive strategies such as dietary and lifestyle changes, physiotherapy with biofeedback, and pharmacotherapy. If conservative methods do not improve symptoms, surgical options are considered, such as sphincter reconstruction, anal sphincter augmentation, and artificial sphincter. Neurostimulation methods, including sacral neuromodulation (SNM), are another option.

Participation in the study will be offered to patients with proven DI who have failed primary conservative treatment. Eligible patients will be indicated to perform the 1st phase of SNM, which consists of inserting a stimulating electrode into the sacral root area and connecting it to an external stimulation source according to the standard procedure [21].

After 2 weeks of stimulation in the test phase, its effectiveness will be evaluated. A positive treatment response is defined as:

An improvement of more than 50% in any of the DI symptoms (according to the bladder and bowel diary in 3 days or 7 days, respectively) and the patient also rates the improvement of her condition as 1 ("very much improved") or 2 ("much improved") using the PGI-I scale An improvement of at least 2 DI symptoms by more than 25% (according to the bladder and bowel diary in 3 days or 7 days, respectively) and the patient also rates the improvement of her condition as 1 ("very much improved") or 2 ("much improved") using the PGI-I scale If the patient achieves a positive treatment response at the end of the test phase, she will be indicated for the 2nd phase of SNM, during which the external stimulation source will be replaced by an implanted stimulation generator. The patient will then continue to be monitored 3, 6 and 12 months after implantation. This will terminate the patient's participation in the study and they will continue to receive treatment or follow-up according to the current clinical recommendations for the treatment of FI and UI.

If the patient does not achieve a positive treatment response at the end of the test phase, the electrode and external stimulator will be removed, the patient will be excluded from the study and will be further monitored or treated according to the current clinical recommendations for the treatment of FI and UI.

Urinary incontinence (UI) is defined as any involuntary leakage of urine. UI has a major impact on the quality of life of affected patients, as well as clearly documented health and socioeconomic consequences.

Conservative (pelvic floor muscle training), semi-invasive (application of so-called "bulking agents" into the urethra) and surgical methods (implantation of tension-free homologous or heterologous bands under the urethra) are used in the treatment of female stress incontinence.

Pharmacotherapy is mainly used in the treatment of urge incontinence. In those patients in whom it is not sufficiently effective or is accompanied by adverse effects, treatment with botulinum toxin applied to the bladder wall or various neuromodulation methods is recommended.

Coexistent fecal and urinary incontinence (double incontinence - DI) is a condition in which symptoms of FI and UI are expressed simultaneously.

Given its high prevalence, DI represents a significant cost to society and healthcare systems. Patients with DI face a number of significant problems that affect their physical (skin irritation and infection, unpleasant odour, hygiene problems, insufficient sleep, etc.) and psychological health (anxiety and depression, social isolation, disrupted relationships, etc.) and quality of life.

Therefore, the treatment of DI is very complex, multidisciplinary and it is very difficult to create uniform clinical recommendations.

Sacral nerve stimulation (SNS) delivers painless electrical impulses to the sacral nerves to improve pelvic organ function. Currently approved indications include urge urinary incontinence, non-obstructive urinary retention, and faecal incontinence. Further studies investigating the treatment outcomes of SNS in patients with DI are therefore highly desirable and needed.

Investigational tools used during the study Patient global impression of improvement (PGI-I) - is a simple screening tool that was created to assess the effect of treatment on a given pathological condition. It is a Likert scale with a rating from 1 ("very much improvement") to 7 ("very much deterioration").

Bladder and bowel diary - is a basic screening tool for assessing the severity of urinary and faecal incontinence symptoms. The patient records data on the time and amount of fluids consumed and data on the time and volume of urine excreted in the diary. She also adds data on the number of episodes of urgency and urinary incontinence. Similarly, she records the number of defecations and data on the number of episodes of urgency and faecal incontinence. The patient records data on urination for 3 days, data on stool for a total of 7 days.

The Wexner Questionnaire - Wexner Score, is a widely used and recognized tool for assessing the severity of faecal incontinence. It serves to objectify and quantify symptoms, which is crucial for diagnosing, monitoring progression, and evaluating the effectiveness of FI treatment. The Wexner Score focuses on five key parameters related to faecal incontinence: gas leakage, liquid stool leakage, solid stool leakage, wearing pads/protective devices, and lifestyle changes. Each of these five parameters is scored on a scale from 0 to 4, where 4 is the worst, and the maximum possible score is 20 points - indicating complete faecal incontinence.

The Faecal Incontinence Quality of Life Scale (FIQL) is a specific quality of life questionnaire designed to assess the impact of FI on various aspects of a patient's life. Unlike incontinence severity scores (such as the Wexner or St. Mark's scores), which only quantify the frequency and type of leakage, the FIQL focuses on how incontinence affects the patient's daily life, psychological well-being, and social interactions. Patients typically rate their feelings or the frequency of the problems on a Likert scale (from 1 to 5, with higher numbers indicating better quality of life or less impact).

The International Consultation of Incontinence Questionnaire - Urinary Incontinence short form (ICIQ-UI SF) is one of the most commonly used tools to assess the effectiveness of interventions in functional urology. This validated questionnaire consists of 3 questions that assess the frequency, severity, and overall impact of incontinence on quality of life. The total score can range from 0-21, with higher scores indicating greater severity of urinary incontinence.

The International Consultation of Incontinence-Overactive Bladder (ICIQ-OAB) is a validated questionnaire used to assess the effectiveness of treatment for urge incontinence and overactive bladder. It consists of 4 questions, focusing on the main symptoms of frequency, nocturia, urgency and urge incontinence. Each question has a sub-question assessing the impact of a specific symptom on quality of life. The total symptom score can be 0-16, the impact score on quality of life can take values of 0-40. In both cases, the higher the score, the greater the severity of urinary incontinence and the greater the negative impact on quality of life.

The Incontinence - Quality of Life (I-QoL) questionnaire is a validated questionnaire assessing the impact of urinary incontinence on patients' quality of life. It consists of 22 questions that the patient answers using a Likert scale from 1 ("Always") to 5 ("Never"). The higher the total score, the better the quality of life, or the smaller the impact of incontinence on quality of life.

Monitoring of the number and severity of treatment-related adverse events (TRAE) will be carried out according to Good Clinical Practice standards.

Inclusion Criteria:

• Adult women over 18 years of age
• Consent to participate in the study
• Willingness to undergo examination, treatment and follow-up according to the protocol
• DI symptoms characterized by:
• Grade III fecal incontinence (patient is unable to consciously hold in wind, loose or hard stools)
• At least 2 episodes of fecal incontinence during the week (according to bladder and bowel diary)
• At least 1 episode of involuntary urine leakage per day (according to bladder and bowel diary)
• Total score of the ICIQ-UI SF questionnaire
• DI symptoms for more than 6 months
• Failure of previous conservative treatment

Exclusion Criteria:

• Rapidly progressing neurological diseases
• Known severe congenital malformations of the anorectum and/or lower urinary tract
• Presence of a foreign body in the urinary tract - urolithiasis, urinary catheter, ureteral stent
• Pregnancy, lactation
• Active urinary tract infection
• Active malignant disease
• Clinically significant pelvic organ prolapse
• Active inflammatory bowel disease (Crohn's disease, ulcerative colitis)
• In the case of an associated lesion of the external anal sphincter, a defect greater than 90 degrees
• Previous pelvic radiotherapy less than 12 months prior to study enrolment
• Previous pelvic organ descent surgery less than 12 months prior to study enrolment
• Previous stress urinary incontinence surgery less than 12 months prior to study enrolment
• Previous childbirth less than 12 months prior to study enrollment
• Anatomical malformations of the sacrum that preclude implantation of the SNM electrode
• Low patient compliance
• Inability to control the neurostimulator

The study is intended for female patients with double incontinence only.

There is no plan to make the individual participant data available to other researchers. The data may be provided upon reasonable request.

No masking is being used in the study.