Five-year Follow-up and Recurrence Rates Following Surgery for Acute and Chronic Pilonidal Disease: A Survey of 421 Cases

Objective. The aim of the present study was to investigate the outcomes of different treatment options for acute and chronic pilonidal disease in a single large cohort of patients.Materials and Methods. Four hundred and twenty-one consecutive patients (171 with chronic disease and 250 with acute abscess formation) who underwent surgery between 2003 and 2012 were included in the present study. Primary outcomes included symptomatic recurrence, time to wound healing, and time off from work. The median follow-up was 5.3 years. Results. In patients with acute abscess formation, the relapse rate was significantly higher (P = 0.0001) if they were treated with abscess excision (38.9%) compared with a wide local excision (13.3%). Time to relapse was significantly longer (P = 0.0205) in patients treated with wide local excision (median 7 vs 3 months), whereas time to wound healing and the days off from work were similar among groups. In chronic disease, the relapse rate was similar in patients treated with wide local excision followed by secondary wound healing (11.3%) when compared with patients treated with limited excision (27.6%) or wide excision with primary wound closure (26.8%). The time to wound healing was shortest in patients with primary wound closure following wide local excision, and the time off from work was not significantly different between groups. Conclusion. Wide local excision with secondary wound healing seems to be the favorable operation method for acute and chronic pilonidal disease.

Pilonidal disease (PD) refers to a common disease affecting mostly young males.^1,2 It may present as asymptomatic pits, acute and painful abscess formation, or chronic discharging sinuses.² Several different treatment options exist for the latter 2 manifestations.² Surgical therapies of acute abscess formation include—among other techniques—incision and drainage, abscess excision, and wide local excision. A chronic disease may be treated with limited or wide excision followed by secondary wound healing, direct skin closure, or reconstructive cutaneous flaps including fasciocutaneous V-Y advancement flaps.^3-6 More recently, fibrin glue injection showed convincing results for treatment of patients with only 1 sinus tract and without previous infections.⁷ Therefore, wide local excision followed by secondary wound healing is presumably the most frequently performed procedure for a chronic disease,⁴ whereas acute abscess formation is commonly treated by abscess drainage followed by elective secondary pilonidal sinus excision.^2,8 None of these surgical therapies has found widespread acceptance.⁹

The aim of the present study was to compare the outcomes of different treatment options for acute and chronic PD, including recurrence rates, time to recurrence, time to complete wound healing, and time off from work.

Patients. All patients treated for PD at a single institution between January 2003 and December 2012 were eligible for inclusion in this retrospective study. Patients treated with primary closure after surgery for acute abscess formation (n = 2) were excluded from the present analysis as well as patients with limited excision of acute abscess formation (n = 5). One of these 2 patients with primary closure and 1 of 5 patients with limited excision of acute abscess showed relapse. These patients were excluded because the authors do not consider limited excision and/or primary closure as standard procedures for acute abscess formations. Eight patients with abscess incision were also excluded from the study because this is not considered a definitive treatment. Furthermore, patients with limited excision and primary closure (n = 2) for chronic disease were excluded due to the small sample size of this group of patients. Both patients showed relapse and were excluded before the statistical analysis was performed independent of their outcome. In total, 433 patient records were analyzed retrospectively. All patients and/or their family doctors were interviewed by phone and/or written questionnaires by the same researcher between February 2013 and March 2014. Four hundred twenty-one patients and/or patients’ family doctors responded to the survey, corresponding to a response rate of 97.2%. When presenting at the authors’ clinics, 14.7% (62 of 421) of patients showed disease recurrence from prior surgery. The median follow-up was 5.3 years (mean: 5.5 years), ranging from 3.5 months to 11.4 years. The local ethics committee approved the study.

Limited excision. Participating patients were placed in the prone position, the buttocks were spread apart using tape, and the cleft of the buttocks was shaved. Diluted methylene blue was injected into the visible pits to mark the course of the sinus tracts. The sinus tracts were closely cut down with electrocautery or using a scalpel following the methylene-marked track, and all tracts and openings were resected.

Wide excision. Patients were placed in the prone position, the buttocks were spread apart using tape, and the cleft of the buttocks was shaved. Diluted methylene blue was injected in all visible pits and a wide spindle-shaped midline excision of the skin and the underlying subcutaneous tissue down to the coccygeal fascia including all sinuses was performed with electrocautery or using a scalpel.

Skin closure was performed in the midline by edge-to-edge approximation of the 2 skin margins using multiple or single-layer sutures. Subcutaneous sutures were used to reduce the wound cavity.

Abscess excision. The patient was placed in the prone position, the buttocks were spread apart using tape, and the cleft of the buttocks was shaved. A spindle-shaped midline excision of the abscess formation was performed with electrocautery or using a scalpel in the operating theatre. The wound cavity was curetted and rinsed.

Wound care. All patients were advised to cleanse the wounds in the shower at least once a day until the wound was completely healed. Patients were then instructed to apply a hair removal cream or to use laser hair removal for at least 6 months after complete wound healing was achieved. Calcium alginate (Algisite, Smith & Nephew, Auckland, New Zealand), hydrofiber (Aquacel, ConvaTec, Deeside, Flintshire, United Kingdom), or wet gauze dressings were inserted into the wounds, or negative pressure wound therapy was applied to promote secondary wound healing. Wound controls were performed as needed by the patients’ general practitioners, by the patients’ relatives, or by home care nurses until complete wound healing was achieved.

Symptomatic recurrence. Disease recurrence was defined as any reappearance necessitating conservative or surgical therapy.

Statistics. The results reported as mean and standard deviation (SD) are shown in Tables 1,2,3. Different statistical tests were applied: 2-tailed unpaired t tests, 2-tailed Fisher’s exact tests, 2-tailed Mann-Whitney tests, 1-way Analysis of Variance (ANOVA) with post hoc Bonferroni’s multiple comparisons tests, Kruskal-Wallis tests with post hoc Dunn’s comparisons of all columns, and chi-square tests with post hoc Bonferroni-corrected 2-tailed Fisher’s exact tests. Furthermore, Kaplan-Meier curves were compared using Log-rank (Mantel-Cox) tests. Changes were rated as significant at P-values < 5 %. Graphic representations and statistical analyses were performed using GraphPad Prism (GraphPad Software, Inc., La Jolla, CA). 

Acute abscess formation. Relapse (21 of 54 patients; 38.9%) and reoperation (20 of 54 patients; 37.0%) rates were significantly higher following abscess excision when compared with wide local excision (26/196; 13.3% and 22/196; 11.2%, respectively). The time to relapse was significantly longer for patients with wide local excision (median: 7 months), compared with patients with abscess excision (median: 3 months). Comparing Kaplan-Meier curves of symptomatic recurrence rates confirmed significantly more (P < 0.0001) recurrences following abscess excision when compared to wide local excision (Figure 1). Multiple reoperations were performed in 3 patients with 1 patient having 3 further surgeries after primary wide local excision and the other 2 patients having 2 additional operations. The length of hospital stay and time away from work were not different between groups. As expected, the length of operation was significantly longer in patients with wide local excision. The time to complete wound healing was not different when comparing patients with wide local excision (median: 8 weeks) to patients treated with abscess excision (median: 6 weeks) (Table 2). 

Chronic pilonidal disease. None of the 29 patients treated with limited excision and 71 of 142 patients (50%) treated with wide local excision had primary wound closure. The remaining patients were treated with secondary wound healing. The relapse rate was not different among groups (11.3% for patients treated with wide local excision, followed by secondary wound healing; 27.6% for patients treated with limited excision; and 26.8% for patients operated with wide excision and primary wound closure). The median time to relapse was also not different among groups (3 months in patients with limited excision, 7 months in patients with wide excision with secondary wound healing, and 9 months in patients with wide excision and primary closure). Comparing Kaplan-Meier curves of symptomatic recurrence rates revealed no significant differences among groups (Figure 2). Multiple reoperations were performed in only 1 patient per group with 1 patient having 3 further surgeries after wide local excision and primary closure and 2 patients undergoing 2 reoperations. As expected, the duration of wound healing was shortest in patients treated with wide excision and primary closure (median: 3 weeks). The length of time to return to work was similar among groups. The length of the hospital stay and the operation time were highest for patients treated with wide excision and primary wound closure (Table 3). 

Several different treatment options for PD exist and the adequate surgical treatments for acute and chronic PD are still unclear.¹⁰ An operation method resulting in low recurrence rates and permitting a short time away from work would be favorable.¹ Thus, the present study was conducted to assess and compare different surgical treatments for PD (including acute abscess formation and chronic disease) with respect to these outcomes. 

The drawback of the present study lies in its retrospective study design, most likely leading to selection bias. The allocation to different treatment groups (ie, different types of surgeries, additional antibiotic treatments, and types of dressings) was not performed randomly, but by the intention of different surgeons to offer the optimal treatment to each patient. Thus, the choice of procedure may reflect the surgeon’s treatment preference, the surgeon’s clinical and operative experience, and/or the patient’s individual clinical presentation. A further drawback represents the follow-up method, since patients’ data were assessed by phone calls or written questionnaires. Hence patients with asymptomatic recurrence or minor discharge from chronic wounds might have been missed or ignored by the general practitioners. This might have led to false negative results. Due to the long follow-up period (median: 5.3 years), information on time to complete wound healing and time away from work arising from the general practitioners’ notes and/or the patients’ memories might be imprecise.

Acute abscess formations may be treated by incision and drainage, unroofing, excision of the abscess, wide local excision, or marsupialization. The percentage of patients sustaining a subsequent surgery following abscess incision shows a huge variation among different reports (ranging from 18%¹¹-85%¹²). This most likely arises because some surgeons routinely perform elective surgical excisions following every drainage or after a certain time period with outstanding wound healing,¹¹ arguing that incision alone may not be a curative procedure.¹³ The ideal interval between incision and definite surgery still needs to be determined.^13,14 Others report curative treatments following incision in more than 50% of the cases and hence do not recommend elective secondary surgery.^2,11,15 Finally, other surgeons perform primary wide local excisions of acute abscess formations and of sinus tracts, arguing these excisions not only treat the acute infection, but also the underlying disease, therefore rendering reoperation unnecessary.^13,16 In the present study, patients with acute abscess formation were either treated by wide local excision of the abscess formation and the underlying sinus tracts or by excision of the abscess cavity only. For patients with abscess excision, relapse rate (38.9%) and necessity for reoperation (37.0%) were in accordance to reports in the literature.^2,11,15 The median time to wound healing was 6 weeks, which is rather short when considering that midline incisions were performed, which probably increased the time to wound healing in comparison to lateral incisions, as reported by Webb and Wysokci.¹¹ Many centers do not perform wide midline excisions of abscess formations, because of the fear of nonhealing wounds.¹⁷ Accordingly, mean time to wound healing was almost 10 weeks in the present study and ranged from 2-68 weeks. Furthermore, in 20 of 196 patients (20%) wound healing lasted 20 weeks or longer.  Two of 196 patients had to undergo multiple additional operations following wide midline abscess excision.

Different treatment options exist for PD presenting with chronically discharging, painful sinus tracts. Limited excision comprises the excision limited to the sinus tracts yielding to shorten the healing period.¹ Three of 29 patients (10.3%) with limited excision in the current study showed more than 4 orifices and 4 of 29 patients (13.8%) presented with relapse, whereas in the literature limited excision is not recommended for patients with complicated (ie, more than 4 pits) or recurrent disease.¹ Furthermore, according to the literature, limited excision may be performed in an outpatient setting under local anesthesia,⁴ whereas in the present study only 3 of 29 patients (10.3%) were outpatients and none of the patients was operated on under local anesthesia. The rather high recurrence rate (27.6%) in this subgroup might be explained by including patients with complicated and/or recurrent disease. Wide excision consists of resection of the entirety of suppuration cavity and all associated pits, aiming to minimize recurrence rates. Whereas some surgeons routinely excise the whole anal cleft, a wide clearance distance was considered as “wide” excision by the present authors. The surgical wound may be closed (ie, primary wound closure) or left open to heal after surgery (ie, secondary wound healing). Secondary wound healing is supposed to reduce recurrence rates, whereas primary closure aims to reduce the healing period. Different types of primary closures exist, consisting of midline sutures with the wound lying in the natal cleft, nonmidline sutures, and different types of tissue flaps. There is no consensus reached yet on which is the best technique of wound closure following pilonidal sinus excision.¹⁸ Despite evidence favoring off-midline sutures,¹⁶ likely by reducing mechanical stress to the wound during postoperative motion,⁹ in the present study, all 71 patients with primary wound closures following wide excision had direct midline closures. When comparing direct wound closure, recurrence rates were not different.

The postoperative course following pilonidal sinus operation may be challenging and different factors contribute to optimal healing conditions. In the present study, patients were advised to use hair removal creams or laser hair removal following complete wound healing in the hopes of limiting the risk of recurrence by preventing bacteria-contaminated hairs from getting into the wound.⁹ Nevertheless, incomplete and traumatic hair removal increases the risk of recurrence,¹⁹ and the optimal method of hair removal (cream, laser, or mechanical shaving) has yet to be determined.²⁰

Taken together, for acute PD wide local excision is more favorable because it results in lower recurrences and similar periods away from work when compared with abscess excision. Abscess excision displayed curative treatments during the study period in slightly more than 60% of the patients suffering from acute PD.

In summary, wide local excision with secondary wound healing appears to be the favorable operation method for chronic PD.

The authors kindly thank Hans Fahrni for his help with data assessment and statistical analysis.They are also grateful towards Ian Forster, PhD, Institute of Physiology, University of Zurich, for proofreading the manuscript.

From the Department of Surgery, Hospital Bülach, Zürich, Switzerland; Department of Pediatric Surgery, University Children’s Hospital of Zurich, Zürich, Switzerland; University of Zurich, Zürich, Switzerland; Department of Surgery, Clinic for Visceral and Thoracic Surgery, Hospital Winterthur, Switzerland; and Mathematic faculty, Cantonal School of Wil, St. Gallen, Switzerland

^*Each of these authors contributed equally to this work.

Address correspondence to:
Raphael Nicolas Vuille-dit-Bille, MD, PhD
Department of Pediatric Surgery
University Children’s Hospital of Zurich
Steinwiesstrasse 75
8032 Zürich, Switzerland
raphael.vuille@access.uzh.ch

Disclosure: The authors disclose no financial or other conflicts of interest.