ENVELOP: Wound Care Following Pilonidal Sinus Surgery (ENVELOP)

September 21, 2026 updated by: Royal College of Surgeons, Ireland

Excision and Negative Pressure Wound Therapy Versus Excision and Leaving Open With Standard Wound Care for Management of Chronic Pilonidal Sinus Disease - A Randomised Controlled Trial

This is a single-blinded, multicentre, prospective randomised controlled trial (RCT) comparing post-operative and patient-reported outcomes for patients undergoing application of negative-pressure wound therapy (NPWT) after sinus tract excision as compared to excision and standard open wound care in chronic pilonidal sinus disease (PSD).

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Pilonidal sinus disease (PSD) is a chronic inflammatory condition of the skin and subcutaneous tissues arising from hair follicles in the natal cleft. The definitive aetiology of the condition is unknown, however, it is theorised that it is the result of either the obstruction and subsequent inflammation of hair follicles or secondary to hair penetrating through the skin into the subcutaneous tissue. This results in infection, abscess formation, chronic discharge and pain. PSD is a common condition affecting 26 per 10,000 population, with the prevalence reaching 1.1% in young adult males.

PSD causes a significant burden on healthcare services due to high rates of recurrence and readmission following surgery, together with negative impacts on patients' quality of life and self-image. An effective management strategy for the disease is necessary to ensure that post-operative outcomes are optimised and patient-reported outcomes are satisfactory in those whose PSD requires surgery.

The objective of this multicentre, national RCT is to prospectively investigate the effect of negative pressure wound therapy compared to leaving open with standard wound care on time to wound healing following surgical excision of chronic PSD.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
200

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • Ireland
      • Castlebar, Ireland
        • Recruiting
        • Mayo University Hospital
        • Contact:
          • Kevin Barry
      • Dublin, Ireland
        • Recruiting
        • Tallaght University Hospital
        • Contact:
          • Dara Kavanagh
      • Dublin, Ireland, D09V2N0
        • Recruiting
        • Beaumont Hospital
        • Contact:
          • John Burke
      • Dublin, Ireland
        • Recruiting
        • St James's Hospital
        • Contact:
          • Michael Kelly
      • Dublin, Ireland
        • Recruiting
        • St Michael's Hospital, Dún Laoghaire
        • Contact:
          • Helen Heneghan
      • Dublin, Ireland
        • Recruiting
        • St Vincent's Univeristy Hospital
        • Contact:
          • Eanna Ryan
      • Kilkenny, Ireland
        • Recruiting
        • St. Luke's Hospital
        • Contact:
          • Cathy Cronin
      • Limerick, Ireland
        • Recruiting
        • University Hospital Limerick
        • Contact:
          • Colin Peirce
      • Tullamore, Ireland
        • Recruiting
        • Midlands University Hospital
        • Contact:
          • Sean Johnston
      • Waterford, Ireland
        • Recruiting
        • University Hospital Waterford
        • Contact:
          • Peter Neary

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

i) They are aged 18 years or older

ii) They are undergoing elective pilonidal sinus excision without primary closure

Exclusion Criteria:

i) They are unable to adhere to protocol requirements e.g. questionnaire completion

ii) They are undergoing emergency drainage for a pilonidal abscess

iii) They are undergoing surgery for pilonidal sinus disease in locations other than the natal cleft

iv) They have underlying osteomyelitis

v) They have underlying fistulating disease e.g. Crohn's

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Negative Pressure Wound Therapy

The wound is dressed using negative pressure wound therapy.
Device: Negative Pressure Wound Therapy

Following elective excision of chronic pilonidal sinus disease with the wound left open, NPWT is applied in theatre using a polyurethane foam-based system (e.g. VAC, Renasys-GO, Prevena or equivalent) cut to fit the wound cavity, sealed with an adhesive drape and connected to a portable pump at -125 mmHg continuous pressure. Dressings are changed every 48-72 hours in clinic until granulation reaches skin level, followed by standard dressings until epithelialisation.
Active Comparator: Standard wound care (SWC)

Following excision, the wound is left open (no primary closure) and managed with standard dressings according to local protocol, with wound healing by secondary intention.
Other: Standard wound care

Standard wound care

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Time to complete wound healing
Time Frame: Up to 6 months post surgery

Number of days to complete epithelialisation or closure of the wound without any discharge, drainage, scab, and/or the requirement for further dressing.
Up to 6 months post surgery

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Measure of post operative pain
Time Frame: Day of surgery, 28 days post surgery & 3 months post surgery

Pain measured by visual analogue pain scale (0 = no pain, 10 = worst pain) at rest, on walking and on sitting
Day of surgery, 28 days post surgery & 3 months post surgery
Measure of post operative complications
Time Frame: 6 months post surgery

Post-operative complications, including surgical site infection (CDC criteria), seroma, abscess, readmission and return to theatre.
6 months post surgery
To compare recurrence rates
Time Frame: 6 months post surgery

To compare the 6-month recurrence rates (recurrence being defined as the development of a new sinus or abscess within the natal cleft occurring after wound healing had been achieved) between the NPWT and SWC Groups
6 months post surgery
Cost-effectiveness
Time Frame: 6 months post surgery

Within-trial cost-utility analysis from health-system and patient perspectives, expressed as incremental cost per QALY gained (QALYs from EQ-5D-5L, area under the curve). Resource use includes hospital and community contacts, dressing changes, complications, readmissions and returns to theatre, valued at Irish unit costs; patient costs and productivity losses via CoPaQ.
6 months post surgery
Health-related quality of life with the EuroQol-5 dimensions five level index questionnaire (EQ-5D-5L)
Time Frame: Baseline, 1 month, 3 months & 6 months

The questionnaire covers five dimensions of health: mobility, self-care, usual activities, pain or discomfort, and anxiety or depression. Each dimension has 5 levels: no problems (1), slight problems (2), moderate problems (3), severe problems (4) and extreme problems (5). The patient is asked to indicate his/her health state by ticking the box next to the most appropriate statement in each of the five dimensions. Index values derived using the EQ-5D-5L value set specified in the Statistical Analysis Plan (Irish value set where available).
Baseline, 1 month, 3 months & 6 months
Scar assessment - using the Patient and Observer Scar Assessment Scale (POSAS)
Time Frame: 28 days, 3 months, 6 months

The POSAS is made up of two scales: the patient and observer scales each comprise six items scored 1 to 10; each scale is summed (6 = normal, 60 = worst) and reported separately.
28 days, 3 months, 6 months
Health-related out-of- Pocket Costs assessed using the Costs for Patients Questionnaire (CoPaQ)
Time Frame: 28 days, 3 months, 6 months

The CoPaQ measures patient and caregivers out-of-pocket expenses (direct and indirect) associated with a health condition
28 days, 3 months, 6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Royal College of Surgeons, Ireland

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Sean T Martin, St. James's Hospital, Ireland

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 1, 2024

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 1, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
June 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 28, 2023

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 16, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 17, 2024

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 24, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 21, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • RCSI-ENVELOP

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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