Postoperative recurrent pilonidal sinus disease is troublesome and its treatment is challenge. Many treatment modalities have been advocated in the treatment of recurrent pilonidal sinus disease; however, there is still no consensus in the literature. Some minimally invasive techniques are used alone or as an adjunct to surgery. Crystallized phenol is the most popular method in the nonoperative treatment of primer pilonidal sinus disease. But its long term effect in the postoperative recurrent cases is unclear. Investigators aimed to present the long-term efficacy of crystallized phenol treatment on postoperative recurrent pilonidal sinus disease through our results collected within the last 20 years.

Study data were collected prospectively and analyzed retrospectively. The demographic data of the patients, other parameters such as smoking, whether they sit a lot due to occupation (sitting at work for at least 6 hours a day), skin tone (whiter, darker), presence of positive family history, BMI (kg/m2, patients were divided into BMI <30 and BMI> 30), pilosity levels (mild,moderate, severe) were also recorded. In addition, the time from the recurrence to admission, the number and type of previous operations, and the status of the sinus at presentation (acute, chronic) were recorded. The presence of purulent discharge from the sinus opening and the presence of signs of inflammation or abscess formation in this region were evaluated as acute pilonidal sinus disease (PSD). The presence of serous discharge from the sinus opening and absence of abscess formation were evaluated as chronic PSD. Investigators investigated whether the factors mentioned above affect the number of applications and recurrence after crystallized phenol treatment (CPT).

The treatment procedure was applied to all patients by one surgical team. One day before the procedure, patients were asked to clean the hair from the waist to the middle of the thighs with depilatory creams or epilation. After local anesthesia was performed around the holes, a thin mosquito clamp was inserted into the sinus and the hairs were removed and the skin around the hole was covered by nitrofurantoin pomade to prevent chemical irritation. Then crystallized phenol was introduced into the sinus with the same clamp. Patients were allowed to return to their daily activities after the procedure. This procedure was performed every 3 weeks. If there was discharge from the wound during the follow-up examination, the procedure was repeated. The closure of the sinus hole and the complete disappearance of the discharge were accepted as healing. After the treatment, follow-up was started. Follow up was done first yearly than five years intervals. All of our patients' contact information was recorded by us and we tried to reach the patients every 5 years by any means (phone or e-mail). Investigators tried to follow them up by contacting them periodically, whether they contact us or not. According to this follow-up, patients were analyzed by divided into 3 groups(1-5 years, 5-10 years, 10-20 years). Patients who could not be reached by any means of communication were included in the unreachable group. Patients were recommended to have hair removal at the wound site once a month for 6 years.

Number of crystallized phenol application, presence of recurrence and number of recurrence after CPT and follow-up data were evaluated. Recurrence of the sinus hole which was found to occur again at least 6 months after being determined to be closed was considered as recurrence. If no recurrence was observed during the follow-up or if post-CPT recurrence was healed after treatment, CPT was considered successful.

Inclusion Criteria:

• Previous operated recurrent pilonidal sinus disease
• Follow-up period of more than 12 months
• The patients who connection by e-mail or telephone

Exclusion Criteria:

• Primer pilonidal sinus disease
• Follow-up period of less than 12 months
• The patients who can't connection by e-mail or telephone

The patients who previous operated recurrent pilonidal sinus disease and who accepted crystallized phenol treatment were included in the study. Patients who at least one year of treatment and contacting later were included in our study.

We are planned to share that all of individual participant data.

The data will become available starting 6 months after publication.

The data will share as SPSS dataset.