Outcomes of Pilonidal Surgery Performed in the Setting of Standard Adjunct Laser Hair Removal: A Retrospective Cohort Study

ABSTRACT

Pilonidal sinus disease (PSD) is associated with substantial morbidity because of wound complications and recurrence after surgery. Adjunct laser hair removal (LHR) has been incorporated into postoperative management in some settings, but real‐world outcomes in cohorts treated uniformly with LHR remain incompletely described. This study aimed to characterize postoperative outcomes after PSD surgery in a large integrated healthcare system in which adjunctive LHR was standard practice and to compare outcomes by surgical approach. We performed a retrospective descriptive cohort study of patients aged 14–89 years who underwent operative treatment of PSD with adjunctive LHR at Kaiser Permanente Northern California between 2012 and 2024. Outcomes included repeat procedures, 30‐day surgical site infection (SSI), and unplanned clinic visits. Outcomes were summarized as proportions overall and by surgical approach. Exploratory bivariable logistic regression examined associations between sex or body mass index (BMI) and outcomes. Multivariable modeling was not performed because of low event counts and sparse covariate distributions, which resulted in unstable models. Among 168 patients, the overall repeat procedure rate was 16.7%, the 30‐day SSI rate was 14.4%, and 39.3% had at least one unplanned clinic visit. Patients treated with Bascom flap closure had fewer repeat procedures (10.4% vs. 20.8%) and fewer unplanned visits (33.8% vs. 43.6%) than those undergoing pilocystectomy, with similar SSI rates (14.9% vs. 14.0%). In exploratory analyses, sex and BMI were not significantly associated with outcomes in either surgical group. In this real‐world cohort managed uniformly with adjunctive LHR, postoperative outcomes appeared to vary more by surgical approach than by sex or BMI. These findings are descriptive and do not estimate the independent effect of LHR. Controlled comparative studies are needed to determine the contribution of LHR to PSD outcomes.

Key Points

• What are the postoperative outcomes of pilonidal sinus disease surgery when adjunctive laser hair removal is incorporated as standard postoperative care, and do outcomes differ by surgical approach?

• In this retrospective cohort of 168 patients treated surgically for pilonidal sinus disease with adjunctive laser hair removal, the overall repeat procedure rate was 16.7%, the 30‐day surgical site infection rate was 14.4%, and 39.3% of patients had at least one unplanned clinic visit. Patients treated with Bascom flap closure had fewer repeat procedures than those treated with pilocystectomy alone, 10.4% versus 20.8%, and fewer unplanned clinic visits, 33.8% versus 43.6%, while 30‐day surgical site infection rates were similar. Exploratory analyses did not identify significant associations between sex or BMI and postoperative outcomes.

• In a real‐world cohort where adjunctive laser hair removal was standard practice, postoperative outcomes appeared to vary more by operative approach than by sex or BMI. These findings provide descriptive benchmarks for pilonidal surgery performed with adjunctive laser hair removal but do not establish the independent effect of laser hair removal because no non‐LHR comparison group was available.

1. Introduction

Pilonidal sinus disease (PSD) predominantly affects adolescents and young adults and is associated with substantial morbidity, recurrence, and healthcare costs [1, 2]. Reported recurrence rates have reached as high as 30%, and much of the disease burden stems from repeat interventions and prolonged wound healing [1]. PSD, once believed to be congenital, is now understood as an acquired condition caused by loose hairs penetrating the skin and triggering chronic inflammation [3]. Known risk factors include dense hair growth, obesity, deep gluteal clefts, poor hygiene, and prolonged sitting [1].

Surgical excision remains the principal treatment, but recurrence and wound morbidity remain common challenges [2]. Adjunctive laser hair removal (LHR) has emerged as a potential strategy to address one of the underlying contributors to disease persistence—hair density—while avoiding some of the limitations of shaving, including poor adherence, inaccessibility, and skin irritation [4]. However, evidence supporting LHR remains heterogeneous.

Recent studies have examined adjunctive LHR as a strategy to reduce PSD recurrence. A 2024 meta‐analysis by Muscat et al. including three randomized controlled trials, demonstrated significantly lower recurrence with LHR (odds ratio 0.319) [5]. Minneci et al. found lower recurrence with LHR versus standard care (10.4% vs. 33.6%) [6], while Ghnnam et al. reported no recurrences at 2 years in patients receiving adjunct LHR after excision with secondary‐intention healing compared with controls [4]. Conversely, Demircan et al. found higher recurrence in LHR groups after Karydakis flap (20% vs. 4%) [7]. Retrospective data from Khan et al. further suggest that adjunct LHR may prolong the disease‐free interval and reduce hair density [8]. These mixed findings underscore the difficulty of isolating the contribution of LHR across studies that vary substantially in operative approach, follow‐up duration, and recurrence definitions [9, 10, 11, 12].

In that context, there is value in describing outcomes in real‐world systems where adjunctive LHR has been incorporated into standard practice. Such cohorts cannot determine the independent efficacy of LHR in the absence of a non‐LHR comparator, but they can provide useful benchmarks for postoperative outcomes and may help clarify whether outcomes vary more by operative approach or by patient‐level characteristics in that setting.

The aim of this study was therefore to characterize postoperative outcomes in patients undergoing surgical treatment of PSD within a large integrated healthcare system in which adjunctive LHR was standard practice and to compare outcomes by surgical approach. Specifically, we examined repeat procedures, 30‐day surgical site infections, and unplanned clinic visits, and explored associations with sex and BMI.

2. Methods

This was a retrospective, descriptive, single‐arm cohort study of patients diagnosed with PSD and treated surgically with adjunctive LHR at Kaiser Permanente Northern California (KPNC) between January 1, 2012, and August 31, 2024. KPNC is an integrated healthcare system serving over 4.5 million members at 21 hospitals and more than 240 outpatient clinics across Northern California.

During the study period, LHR was standard practice at KPNC for patients undergoing surgical management of PSD. As such, a non‐LHR control group was not available. This study therefore describes outcomes in a cohort of patients treated with pilonidal surgery and adjunctive LHR and was not designed to estimate the independent effect of LHR.

Regarding LHR, patients were treated with a Candela GentleMax Pro laser that has both an Alexandrite laser (755 nm) and an Nd:YAG laser (1064 nm). Alexandrite was used for patients with skin Type I–III, and Nd:YAG was used for patients with skin Type IV–VI. All treatments were performed by registered nursing staff trained in laser hair reduction. For most patients, an area extending at least 2 cm on either side of and above and below the surgical scar was treated to reduce the risk of recurrence.

2.1. Study Population

Patients aged 14–89 years who underwent cyst excision with adjunctive LHR were included. Exclusion criteria included nonoperative management or diagnosis before age 14 or after age 89.

2.2. Data Sources and Variables

Data were extracted from the KPNC electronic health record and administrative databases, including demographics, operative details, comorbidities, perioperative antibiotic use, and postoperative outcomes. Outcomes included repeat procedures, 30‐day surgical site infection (SSI), and unplanned clinic visits. A repeat procedure was defined as any subsequent incision and drainage (I&D) or re‐excision following the index procedure. SSI was recorded as any documented infection within 30 days postoperatively. Unplanned clinic visits were defined as outpatient visits occurring outside of routine follow‐up. These outcomes were analysed as proportions of the study population, with missing data excluded listwise.

2.3. Statistical Analysis

Descriptive statistics were used to summarize baseline demographics and outcomes. Repeat procedure, SSI, and unplanned clinic visit rates were calculated as proportions. Logistic regression was used to examine associations between sex or BMI and binary outcomes. BMI was modelled as a continuous predictor, while sex was modelled categorically. Multivariable analysis was not performed because outcome events were relatively infrequent and several candidate covariates were sparse, which resulted in unstable models and singular matrix errors. To avoid overfitting and uninterpretable estimates, analyses were therefore limited to descriptive comparisons and exploratory bivariable models. Results are reported as odds ratios (ORs) with 95% confidence intervals (CIs) and p values.

All analyses excluded missing data listwise and were conducted using Python (v3.11). This study was approved by the Kaiser Permanente Northern California Institutional Review Board (IRB #2235580).

3. Results

A total of 168 patients met inclusion criteria, including 101 who underwent pilocystectomy with adjunctive LHR and 67 who underwent cyst excision with Bascom flap closure and adjunctive LHR. Demographics are shown in Table 1. Mean age was 23 years in the pilocystectomy group and 24 years in the Bascom flap group. Most patients in both groups were male.

TABLE 1.

Demographics.

Procedure	Pilocystectomy only (n = 101)	Bascom flap only (n = 67)
Age
Mean	23	24
STD	9	10
Min	13	14
50%	20	20
Max	68	67
Sex, n (%)
M	73 (72.3%)	49 (63.6%)
F	28 (27.7%)	18 (23.4%)
Co‐morbidity, n (%)
DM	3 (3.0%)	1 (1.5%)
Smoker	11 (11.0%)	2 (3.0%)
Steroid use	0 (0%)	2 (3.0%)
Immunosuppression	1 (1.0%)	2 (3.0%)
Immobility	0 (0%)	0 (0%)
Malnutrition	1 (1.0%)	0 (0%)

3.1. Primary Outcomes

Across the full cohort, the repeat procedure rate was 16.7%, the 30‐day SSI rate was 14.4%, and 39.3% of patients required at least 1 unplanned clinic visit (Table 2).

TABLE 2.

Complication rates.

Group	Total repeat procedure rate (%) (re‐excision, I&D) (n)	30‐day SSI (%)	≥ 1 Unplanned clinic visit (%)
All patients (n = 168)	16.7 (21.7)	14.4	39.3
LHR after pilocystectomy only (n = 101)	20.8 (16.5)	14.0	43.6
LHR after Bascom flap only (n = 67)	10.4 (5.2)	14.9	33.8

Note: Repeat procedure rate is the total rate including re‐excision and I&D cases.

By surgical approach, patients undergoing pilocystectomy with adjunctive LHR (n = 101) had a repeat procedure rate of 20.8% (including re‐excision and I&D), a 30‐day SSI rate of 14.0%, and an unplanned clinic visit rate of 43.6%. Those treated with Bascom flap closure and adjunctive LHR (n = 67) had lower repeat procedures (10.4%), similar 30‐day SSI rates (14.9%), and fewer unplanned clinic visits (33.8%) (Table 2).

When repeat procedures were limited to re‐excision and excluded I&D, re‐excision remained less frequent after Bascom flap closure (7.5%) than after pilocystectomy (14.9%) (Table 3). In the pilocystectomy group, re‐excisions included 11 sharp re‐excisions in the operating room, 4 sharp re‐excisions in the office, and 1 trephination procedure. In the Bascom flap group, re‐excisions included 4 sharp re‐excisions in the operating room and 1 sharp re‐excision in the office.

TABLE 3.

Re‐excision approach.

	Sharp re‐excision in OR (n)	Sharp re‐excision in office (n)	Trephination (n)	Re‐excision rate excluding gips (%)
LHR after pilocystectomy only (n = 101)	11	4	1	14.9
LHR after Bascom flap only (n = 67)	4	1	0	7.5

3.2. Secondary Outcomes

Sex and BMI were not significantly associated with repeat procedure, SSI, or unplanned clinic visit in either surgical group (Tables 4 and 5). These findings should be interpreted cautiously because the analyses were exploratory and not adjusted for additional clinical covariates.

TABLE 4.

Association of demographics with outcomes: pilocystectomy only.

Outcome	Variable	OR	95% CI	p
Repeat procedure	Sex (M vs. Ref)	1.21	0.35–4.23	0.76
Repeat procedure	BMI	0.94	0.84–1.06	0.31
30‐day SSI	Sex (M vs. Ref)	5.71	0.70–46.92	0.1
30‐day SSI	BMI	1.04	0.93–1.16	0.47
Unplanned clinic visits	Sex (M vs. Ref)	1.45	0.57–3.71	0.43
Unplanned clinic visits	BMI	1	0.92–1.08	0.93

TABLE 5.

Association of demographics with outcomes: Bascom flap only.

Outcome	Variable	OR	95% CI	p
Repeat procedure	Sex (M vs. Ref)	0.9	0.16–5.16	0.91
Repeat procedure	BMI	0.94	0.80–1.11	0.49
30‐day SSI	Sex (M vs. Ref)	0.49	0.12–1.98	0.32
30‐day SSI	BMI	1.01	0.88–1.14	0.93
Unplanned clinic visits	Sex (M vs. Ref)	1.38	0.44–4.29	0.58
Unplanned clinic visits	BMI	1.01	0.92–1.11	0.82

4. Discussion

In this 12‐year, single‐system cohort of patients undergoing surgical treatment of PSD in the setting of standard adjunctive LHR, outcomes appeared to vary more by surgical approach than by sex or BMI. Patients treated with Bascom flap closure had fewer repeat procedures and fewer unplanned clinic visits than those treated with pilocystectomy, while SSI rates were similar. This pattern is consistent with prior reports suggesting that off‐midline flap‐based approaches may reduce wound tension, hair trapping, and recurrent midline disease [13, 14, 15, 16, 17].

The principal contribution of this study is descriptive rather than causal. Importantly, this study does not evaluate the independent efficacy of LHR because all included patients received adjunctive LHR as part of standard care and no non‐LHR comparator group was available. Instead, it provides real‐world benchmarking data from a large integrated healthcare system over a 12‐year period and describes outcomes across 2 commonly used operative approaches within a uniform LHR‐treated cohort. This distinction is important because the literature on LHR remains mixed. Prior randomized and retrospective studies have varied considerably in operative technique, recurrence definition, comparator groups, follow‐up duration, and laser protocols [4, 5, 6, 7, 8, 11, 12].˒ As a result, it is difficult to isolate the contribution of LHR across studies. Our cohort cannot answer whether LHR improves outcomes relative to no LHR, but it does provide clinically relevant information about what postoperative outcomes look like in routine practice when LHR is embedded in care delivery.

The exploratory regression analyses did not identify significant associations between sex or BMI and outcomes. These null findings should be interpreted cautiously. The study was not optimized for robust adjusted modelling, and outcome events were relatively infrequent. In addition, several candidate covariates were sparse, making multivariable modelling unstable. For this reason, we limited analyses to descriptive comparisons and exploratory bivariable regression.

The strengths of this study include the relatively large sample size, long study period, integrated healthcare setting, and detailed characterization of repeat procedure types. The limitations are threefold. First, the retrospective single‐arm design precludes causal inference regarding the effect of adjunctive LHR. Second, recurrence‐related outcomes in the PSD literature are inconsistently defined, limiting external comparison [9, 10, 11, 12]. Third, because this was a real‐world EHR‐based study, some variables of interest, including disease severity, adherence to postoperative care, and degree of hair reduction achieved, were not available in a standardized fashion.

Durable control of PSD likely depends on both surgical technique and adjunctive measures like LHR. While LHR may contribute to reduced recurrence risk by addressing hair regrowth, comparative studies are needed to define the independent contribution of LHR and to determine how best to integrate LHR with specific surgical techniques and patient subgroups [18, 19, 20].

5. Conclusion

In this real‐world cohort of patients undergoing PSD surgery in the setting of standard adjunctive LHR, Bascom flap closure was associated with fewer repeat procedures and fewer unplanned clinic visits than pilocystectomy, while SSI rates were similar. These findings do not establish the independent benefit of LHR, but they provide descriptive benchmarks for outcomes in routine practice. Prospective controlled studies are needed to determine the specific contribution of LHR to postoperative PSD outcomes.

Funding

The authors have nothing to report.

Ethics Statement

This study was reviewed and approved by the Kaiser Permanente Northern California Institutional Review Board (IRB #2235580).

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.