An interventional study of Transcutaneous Genital Nerves Stimulation in Refractory Visceral Pelvic Pain and Refractory Genital Pain, sponsored by Prof. Dr. med. Marc Possover. Not yet recruiting at 1 site in Switzerland. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-20.
Sponsored by Prof. Dr. med. Marc Possover · Not applicable, Interventional, and Treatment
This study will explore whether non-invasive electrical stimulation can reduce chronic genital pain, deep pelvic pain, or both in adult women whose symptoms have persisted for at least six months despite conventional treatment.
Approximately 50 women will participate at several clinical centers. After recording their pain for two weeks, participants will use a portable electrical stimulation device at home for 12 weeks. Two adhesive electrodes will be placed on intact skin beside the vulva. Stimulation will be applied for 30 minutes twice daily, at an individually adjusted, comfortable intensity. No surgery or implantation is required.
The main outcome is the proportion of participants achieving at least a 30% reduction in their main pain symptom after 12 weeks. Researchers will also assess daily functioning, quality of life, pain medication use, and side effects. Follow-up assessments will take place three and six months after treatment ends.
All participants will receive stimulation; there is no comparison group. This exploratory study aims to assess safety, tolerability, and preliminary signs of benefit to guide a future controlled trial.
GNS-PAIN is a prospective, multicenter, single-arm proof-of-concept study investigating transcutaneous perivulvar electrical stimulation in adult women with treatment-refractory chronic genital pain, deep visceral pelvic pain, or both. The study aims to estimate the proportion of participants experiencing clinically meaningful pain improvement and to assess feasibility, safety, and tolerability.
Eligible participants have experienced pain for at least six months despite appropriate conventional medical management. A diagnostic evaluation must exclude an active condition requiring specific causal treatment, such as active endometriosis adequately explaining the current symptoms, pelvic malignancy, infection, or identifiable pelvic nerve entrapment or injury. Previous endometriosis or pelvic surgery does not itself preclude participation. Participants must have an average baseline pain intensity of at least 4 on a numerical rating scale from 0 to 10 in their designated main pain domain.
Genital pain and visceral pelvic pain will be assessed separately. Before treatment begins, each participant will have an index pain domain designated as either genital or visceral pelvic pain. For participants with both types of pain, the more burdensome domain will be selected. This designation will remain unchanged throughout the study and will determine the primary outcome.
Following screening and informed consent, participants will complete a 14-day baseline period, recording daily pain intensity and analgesic medication use. They will then receive training in device operation, electrode placement, stimulation intensity adjustment, and safety precautions before beginning 12 weeks of home-based treatment.
Stimulation will be delivered using a portable transcutaneous electrical nerve stimulation (TENS) device and two self-adhesive electrodes placed on intact skin approximately 2-3 cm lateral to the vulva. Neither electrode will be placed on the clitoris or vulvar or vaginal mucosa. The intervention involves no intracavitary electrode, skin penetration, or implantation.
The stimulation frequency will be 20 Hz. Participants will gradually increase the intensity until a mild tingling sensation is perceived and then slightly reduce it to maintain comfortable stimulation. Treatment sessions will last 30 minutes and will be performed twice daily, in the morning and evening. Device use and electrode placement will be standardized across participating centers through a dedicated stimulation manual.
The primary endpoint is the proportion of participants achieving at least a 30% reduction in mean daily pain intensity in their prospectively designated index pain domain at Week 12. The mean score from the final seven days of treatment will be compared with the mean score from the 14-day baseline period.
Secondary outcomes include the proportion achieving at least 50% pain reduction, changes in mean and worst pain intensity, pain interference with daily activities, Patient Global Impression of Change, analgesic medication use, and health-related quality of life. Associated urinary, bowel, and sexual symptoms will also be assessed. Exploratory analyses will examine responses separately in participants with predominantly genital pain, predominantly visceral pelvic pain, and mixed genital-visceral pain.
Follow-up assessments will take place three and six months after completion of treatment, without continued study stimulation, to assess persistence or loss of any observed benefit. Adverse events, including skin irritation, stimulation-related discomfort, and worsening pain or pelvic symptoms, will be monitored throughout treatment and follow-up. Stimulation will be discontinued if clinically significant or intolerable treatment-related adverse effects occur.
The proposed rationale is that stimulation of sensory pathways in the genital region may influence pelvic pain processing. However, recruitment of specific deep pelvic autonomic structures has not been demonstrated with this skin-electrode configuration, and analgesic efficacy in the study population remains unproven.
There is no control or sham-stimulation group. Accordingly, observed improvements cannot be conclusively attributed to stimulation rather than placebo effects, natural symptom fluctuations, or regression to the mean. The findings will provide preliminary response estimates and feasibility information to inform the design of a subsequent randomized, sham-controlled trial.
117 studies on the registry are indexed under Vulvodynia; 21 are open to participants now.
This study's planned enrollment of 50 is close to the median of 46 across 89 interventional studies indexed under Vulvodynia.
Browse Vulvodynia studies →Prof. Dr. med. Marc Possover is the lead sponsor of 4 studies on the registry; 3 are open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
All of the following must be met:
Exclusion Criteria:
Participants will be excluded in the presence of:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Relapsed and refractory
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive bilateral transcutaneous genital nerve stimulation (GNS) using adhesive skin electrodes placed on the perivulvar skin, approximately 2-3 cm lateral to the vulva. Stimulation will be administered at 20 Hz for approximately 30 minutes twice daily. Stimulation intensity will be adjusted to a comfortable sensory level. The intervention aims to evaluate the feasibility, safety, and preliminary therapeutic effects of GNS in women with refractory chronic genital and/or visceral pelvic pain.
Device: Transcutaneous Genital Nerves Stimulation
Transcutaneous genital nerve stimulation (GNS) will be administered using an external electrical nerve stimulation device connected to bilateral adhesive skin electrodes positioned approximately 2-3 cm lateral to the vulva on intact perivulvar skin. Stimulation will be delivered at a frequency of 20 Hz for approximately 30 minutes twice daily. The stimulation intensity will be individually adjusted to produce a comfortable tingling sensation and then slightly reduced to maintain tolerability. Following initial instruction, participants will self-administer the treatment at home according to the study protocol. No vaginal or mucosal electrodes, surgical procedures, or implanted devices will be used.
Change in Genital and/or Visceral Pelvic Pain Intensity
Change in patient-reported pain intensity from baseline, assessed using a 0-10 Visual Analog Scale (VAS), where 0 represents no pain and 10 represents the worst imaginable pain. Genital and visceral pelvic pain will be assessed separately, according to the symptoms present at baseline. Higher scores indicate greater pain intensity. A reduction in score indicates improvement.
Time frame: Baseline and 12 weeks after initiation of treatment
Patient Global Impression of Improvment (PGI-I)
Patient-reported overall improvement assessed using the 7-point PGI-I scale, ranging from 1 (very much better) to 7 (very much worse).
Time frame: Baseline and 12 weeks after initiation of treatment
Change in Sitting Tolerance
Change in the maximum duration of sitting tolerated before pain becomes intolerable, measured in minutes and compared with baseline.
Time frame: Baseline and 12 weeks after initiation of treatment
Change in Health-Related Quality of Life assessed by the EQ-5D-5L Visual Analogue Scale (EA VAS)
Change from baseline in self-reported health status assessed using the EuroQol 5-Dimension 5-Level questionnaire (EQ-5D-5L), specifically its visual analogue scale (EQ VAS). The EQ VAS ranges from 0 (worst imaginable health) to 100 (best imaginable health). Higher scores indicate better self-reported health status. The outcome is the change in EQ VAS score from baseline to 12 weeks.
Time frame: Baseline and 12 weeks after initiation of treatment
Proportion of Participants Achieving at Least 50% Pain Reduction
Percentage of participants achieving a reduction of at least 50% in their prespecified target pain score compared with baseline, measured on a 0-10 pain scale.
Time frame: Baseline and 12 weeks after initiation of treatment
Incidence of Treatment-Related Adverse Events
Number and proportion of participants experiencing treatment-related adverse events, including skin irritation, discomfort during stimulation, or worsening of pelvic or genital pain.
Time frame: Baseline and 12 weeks after initiation of treatment
Plan to share: No
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From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Prof. Dr. med. Marc Possover