Pit-Picking Combined with Microwave Ablation Versus Pit-Picking Alone for Pilonidal Sinus Disease: A Retrospective Multicenter Comparative Cohort Study

1. Introduction

Pilonidal sinus disease (PSD) is a chronic inflammatory disorder of the sacrococcygeal region that predominantly affects young adults and is associated with significant morbidity, prolonged wound care, loss of productivity, and impaired quality of life [1,2]. Although numerous surgical techniques have been described, an ideal treatment modality that simultaneously minimizes recurrence, postoperative pain, and wound complications has not yet been established [3].

Traditional excisional procedures remain effective but are associated with prolonged healing time, postoperative discomfort, and delayed return to work [4,5]. Pit-picking, first popularized by Bascom, represents one of the most widely adopted minimally invasive techniques [6], allowing rapid postoperative recovery through limited excision. Nevertheless, recurrence rates remain variable [7,8].

Several adjunctive modalities — including endoscopic treatment (EPSiT), laser ablation, phenol application, and radiofrequency-based techniques — have been investigated to improve treatment durability [9,10,11,12,13]. Among these, microwave ablation (MWA) has recently attracted attention as a novel energy-based modality capable of achieving effective thermal destruction of sinus epithelium and inflammatory tissue with minimal collateral injury [14,15]. The Tezel classification (Figure 1) is used to grade disease morphology and guide treatment selection [16].

The aim of the present study was to compare perioperative outcomes, postoperative recovery, complications, and recurrence rates between pit-picking combined with MWA and conventional pit-picking alone in patients with PSD.

2. Materials and Methods

2.1. Study Design and Patient Population

This retrospective multicenter comparative cohort study included consecutive patients who underwent surgical treatment for PSD at two tertiary referral centers between January 2022 and January 2024. A total of 403 patients were enrolled: 200 in the MWA group and 203 in the PP group. The study protocol was conducted in accordance with the Declaration of Helsinki, and the study protocol, covering both participating centers, was approved by the Scientific Research Ethics Committee of the University of Health Sciences Şehit Prof. Dr. İlhan Varank Training and Research Hospital (approval no: 2026/336; date of approval: 24 June 2026); institutional permission for participation was additionally obtained from Balıkesir Atatürk City Hospital. A flow diagram of patient selection is shown in Figure 2.

2.2. Treatment Allocation and Patient Counseling

All patients received standardized counseling regarding both procedures. Treatment allocation was entirely patient-driven, minimizing surgeon-related selection bias. The groups did not differ meaningfully in terms of disease severity, symptom duration, or prior abscess history (Table 1).

2.3. Surgical Technique

All procedures were performed under local anesthesia in an outpatient setting by surgeons experienced in the management of PSD.

In the PP group, all visible midline pits were excised using 3–4 mm skin punches. The sinus tracts were subsequently curetted to remove hair and granulation tissue, followed by irrigation with saline solution. The wounds were left open to heal by secondary intention.

In the MWA group, pit excision and sinus tract debridement were performed in the same manner as described for the PP group. Subsequently, microwave ablation was applied using the ECO Microwave Ablation System (Medel Healthcare, Turkey). This system consists of a touchscreen-controlled microwave generator and dedicated disposable microwave antennas designed for precise thermal energy delivery. The device permits controlled tissue ablation through flexible probes of varying lengths, facilitating effective destruction of residual sinus epithelium while minimizing collateral tissue injury.

Following pit excision and curettage, the microwave antenna was introduced into the sinus tract through each pit opening, and microwave energy was delivered along the entire tract according to the manufacturer's recommendations. The same microwave platform was used throughout the study period to ensure procedural consistency and minimize device-related variability. Procedural steps and device settings were standardized across both participating centers.

2.4. Outcome Definitions and Follow-Up

The primary outcome was disease recurrence, defined as any clinical reappearance of a pit, abscess, or discharging sinus confirmed on physical examination. Secondary outcomes included operative time, VAS pain scores (0–10), complications, SSI, wound healing time, time to pain-free sitting, and time to return to work.

All patients were assessed at 1 week, 4 weeks, 3, 6, and 12 months, and annually thereafter. Median follow-up was 16 months (IQR 12–22) with no significant between-group difference (p=0.812).

2.5. Statistical Analysis

Categorical variables were compared using the chi-square or Fisher's exact test; continuous variables using Student's t-test or Mann–Whitney U test, and reported as mean ± SD or median (IQR). Odds ratios (OR) with 95% confidence intervals (CI) were calculated for binary outcomes. Multivariable binary logistic regression was performed incorporating variables with p<0.10 on univariable analysis. Recurrence-free survival was estimated using the Kaplan–Meier method and compared with the log-rank test. Statistical significance was defined as p<0.05. All analyses were performed using SPSS version 27.0 (IBM Corp., Armonk, NY, USA). This study was reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.

3. Results

3.1. Baseline Characteristics

A total of 403 patients were included. Baseline demographic and clinical characteristics were comparable between groups (Table 1). All patients had Tezel Class III or higher disease, reflecting the referral population of the participating tertiary centers. Tezel Classes I and II were absent because these patients are typically managed conservatively at our institutions.

3.2. Surgical and Postoperative Outcomes

Median operative time was modestly longer in the MWA group (22 vs 15 min, p<0.001). All postoperative recovery parameters significantly favored the MWA group: shorter pain-free sitting (2 vs 4 days, p<0.001), faster healing (11 vs 16 days, p<0.001), and earlier return to work (3 vs 5 days, p<0.001). Complication rates were lower (4.5% vs 11.3%; OR 0.37, 95% CI 0.16–0.84; p=0.018) and SSI rates were lower (1.5% vs 5.4%; OR 0.26, 95% CI 0.07–0.95; p=0.031). Full results are shown in Table 2.

3.3. Recurrence

Recurrence rates were significantly lower following pit-picking combined with MWA compared with pit-picking alone (5.5% vs 13.8%; OR 0.36, 95% CI 0.17–0.75; p=0.006). Kaplan–Meier analysis demonstrated significantly higher recurrence-free survival in the MWA group (log-rank p=0.005) (Figure 3). Median time to recurrence was not reached in the MWA group; in the PP group, median time to recurrence was 14 months (IQR 9–18).

Figure 3. ECO Microwave Ablation System (Medel Healthcare, Turkey) used for microwave-assisted treatment of pilonidal sinus disease. The system comprises a touchscreen-controlled microwave generator and dedicated disposable microwave antennas for controlled thermal tissue ablation.

Figure 3. ECO Microwave Ablation System (Medel Healthcare, Turkey) used for microwave-assisted treatment of pilonidal sinus disease. The system comprises a touchscreen-controlled microwave generator and dedicated disposable microwave antennas for controlled thermal tissue ablation.

Figure 3. Kaplan–Meier curves for time to recurrence comparing pit-picking alone (red) versus pit-picking with microwave ablation (blue). Tick marks indicate censored observations (log-rank p=0.005).

Figure 3. Kaplan–Meier curves for time to recurrence comparing pit-picking alone (red) versus pit-picking with microwave ablation (blue). Tick marks indicate censored observations (log-rank p=0.005).

3.4. Recurrence Risk Stratification

Kaplan–Meier analysis by Tezel classification demonstrated significantly higher recurrence rates with increasing disease severity (Tezel III: 5.5%; IV: 16.5%; V: 11.5–11.9%; log-rank p<0.001) (Figure 4). Patients with postoperative complications had significantly higher recurrence rates compared with those without complications (log-rank p<0.001) (Figure 5).

3.5. Multivariable Analysis

On multivariable logistic regression, MWA treatment remained an independent predictor of reduced recurrence (adjusted OR 0.35, 95% CI 0.16–0.76; p=0.007). Higher Tezel class (Class V vs III: OR 2.81, 95% CI 1.09–7.25; p=0.032) and previous abscess drainage (OR 2.14, 95% CI 1.03–4.42; p=0.041) were independently associated with increased recurrence risk (Table 3).

4. Discussion

The principal finding of the present study is that the addition of microwave ablation to pit-picking significantly improved postoperative outcomes and reduced recurrence rates compared with pit-picking alone in patients with pilonidal sinus disease. Our results demonstrated that pit-picking combined with MWA was associated with lower postoperative pain scores, fewer wound-related complications, faster recovery, and superior long-term disease control, with MWA remaining an independent predictor of reduced recurrence on multivariable analysis.

Recurrence following pit-picking alone remains a significant concern. Our recurrence rate of 13.8% in the PP group is consistent with previously reported rates of 10–18% for pit-picking alone [7,8], while the 5.5% recurrence rate in the MWA group compares favorably with endoscopic and laser-assisted techniques [9,10,11,12,13]. MWA may improve treatment durability through more effective eradication of residual sinus epithelium and inflammatory tissue. Its localized thermal effect may additionally reduce bacterial burden and contribute to coagulative tissue sealing [14,15].

Postoperative pain and recovery parameters significantly favored pit-picking combined with MWA. Patients in the MWA group experienced earlier pain-free sitting, shorter healing time, and faster return to work — findings of particular clinical importance given that PSD predominantly affects young adults during their most productive years.

Tezel classification and prior abscess drainage emerged as independent recurrence predictors on multivariable analysis, reinforcing existing literature on disease severity as a determinant of outcome [16]. These factors should be considered in patient counseling and preoperative risk stratification.

Several limitations should be acknowledged. The retrospective design inherently carries risk of unmeasured confounding. The median follow-up of 16 months may be insufficient to capture late recurrences. Procedural standardization across surgeons and centers may not have been entirely uniform. Propensity-score matching was not feasible given the sample size. Future prospective randomized studies with larger cohorts and extended follow-up are necessary to validate these findings.

5. Conclusions

Pit-picking combined with microwave ablation represents an effective and promising minimally invasive treatment strategy for pilonidal sinus disease. Compared with pit-picking alone, adjunctive microwave energy application provided significant advantages regarding postoperative pain control, wound healing, complication rates, and time to functional recovery while also achieving substantially lower recurrence rates. MWA treatment was an independent predictor of reduced recurrence on multivariable analysis, even after adjusting for disease severity. Further prospective randomized multicenter studies with longer follow-up are necessary to confirm the long-term efficacy of microwave-assisted treatment.