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Pilonidal disease.


The number of terms associated with this phenomenon are evidence of its poorly understood pathophysiology and the varied views of different clinicians. These are frequently called pilonidal cysts, but the terms pilonidal sinus, pilonidal disease, and pilonidal abscess may be applied. The term cyst generally applies to a lined subcutaneous cavity and does not indicate whether infection is present. Pilonidal cysts are generally only discussed when an individual has an obvious infection. Following a surgical procedure, patients are frequently referred to physical therapy for management of the wound created during surgical management.

In its general usage, the term pilonidal cyst refers to an area located at the superior aspect of the gluteal cleft in the sacrococcygeal area as shown in Figure 1. This area is known as the natal cleft. Speculation on the etiology of pilonidal disease frequently centers on either the development of the natal cleft or the environment created within the natal cleft. The terms pilus and nidus imply a nest of hair; while hairs may occasionally be found within the abscessed area, their presence is not required or necessarily expected.

Pilonidal cysts may be relatively asymptomatic, chronic, or acute. A person might have an area that is softer or more firm than surrounding tissue, but not painful. The person can be aware of the area and even have an opening from the cyst (or sinus, i.e., a sinus tract), that drains chronically. Two such openings are seen in Figure 1. If the pilonidal cyst does not produce any overt signs of infection or cause distress, that individual is frequently not well motivated to seek medical attention. However, these areas of seemingly minor significance may become rapidly symptomatic.

With infection, the individual may progress rapidly from discomfort in the area of the coccyx during sitting to extreme pain, drainage of frank pus, and other typical signs of infection such as erythema and warmth. Medical treatment with antibiotics may be received and the pain, edema, and drainage may subside; however, recurrence is common. In other cases, medical attention may be delayed until the person has excruciating pain in positions in addition to sitting. At this point, surgical intervention in addition to use of antibiotics becomes imminent. Incision and drainage (I & D) may be performed by an emergency department physician and the patient sent home. Others may be seen by a surgeon and scheduled for more extensive surgery. A number of patients who have received I & D will have rapid recurrence and will receive either repeat I & D or be referred to a surgeon. Fever and sepsis can occur, but are rare. A rare complication of chronicity is squamous cell carcinoma.



Despite a long history of research into this problem, the etiology of the pilonidal cyst remains controversial and the relationships between abscess development and risk factors are unclear. The vast majority of abscesses are diagnosed in teenagers to young adults and virtually all of those who develop pilonidal abscesses demonstrate gluteal hypertrichosis (excessive hair growth) as demonstrated in Figure 1. This age range corresponds with the development of body hair and suggests a relationship between gluteal hypertrichosis and abscess development. Other risk factors suggested by various sources include obesity, poor hygiene, excess sweating, and coarseness of body hair.

The relationship with hairs is supported by the presence of similar abscesses that have been reported to develop on the hands of those who work on hair (barbers, sheep shearers, dog groomers). Loose hair in the gluteal cleft, inadequate hygiene, and prolonged sitting have been suggested as causative factors via penetration of contaminated hairs into the skin. Historically, military personnel who experienced frequent bumpy rides in jeeps have experienced disproportionate numbers of these abscesses. Others have suggested that trauma to hair follicles leads to rupture and infection with spread into an abscess.

Some suggest that a pre-existing subcutaneous defect may be present and later becomes infected with the development of coarse body hair. Although children may be born with a sacral dimple and some of these may develop abscesses, not all children with sacral dimples eventually develop abscesses. A familial link to pilonidal abscess has been shown clearly. (1) Both the appearance of abscesses and recurrence rate are associated strongly with a family history of abscesses. An anatomic basis is supported by a study showing a pre-existing structural difference in the skin of those developing abscesses. The natal cleft was found to be significantly deeper in those with pilonidal disease (27 mm) than in those without disease (21 mm), whereas other measures of body dimensions were not different (BMI of 25.71 vs 25.28 for control subjects). (2) Therefore, a combination of genetically determined difference in natal cleft anatomy, the presence of gluteal hypertrichosis, and trauma to the natal cleft may be responsible for this phenomenon. A genetic link has not yet been demonstrated conclusively between natal cleft anatomy and gluteal hypertrichosis. Whether these are genetically co-determined or independent risk factors has not yet been elucidated.

Surgical treatment

Surgical treatment for these abscesses may entail simple incision and drainage, excision with primary closure, excision with coverage by a flap procedure, and excision allowing closure by secondary intent. Although pilonidal abscesses are frequently treated with incision and drainage, they do not heal well and these infections are notoriously recurrent even after wound closure. (1,3) Although recurrences may appear within days, they may also appear much later. As many as 25% of recurrences have been found more than five years after the first surgical procedure. (1) Many reasons have been proposed for recurrence, such as the type of surgical procedure done or failure to address risk factors. Closure of a midline incision has been suggested as the reason for such high recurrence with simple excision and closure procedures. Failure to identify the entire infected mass may also be to blame. Pre-op ultrasound imaging has the potential to identify areas of the abscess that might be missed with a simple I & D procedure. In one study, 23% of abscesses had areas that were found by ultrasound, but were missed by physical exam by the surgeon. (4)

More complex procedures using flaps have been designed to avoid leaving a suture line within the natal cleft. The modified Karydakis procedure is also known as a cleft lift or cleft closure. This procedure is used to create a shallower natal cleft. The justification for this procedure is that deeper clefts are a risk factor for recurrence; therefore, a procedure that flattens the cleft is less likely to have a recurrence. After the involved tissue is excised, a flap of tissue is pulled from one side to the center, which creates the shallower natal cleft and replaces the original midline skin with more lateral skin that is believed to be less prone to infection. This procedure appears to have a much lower recurrence rate (5%) than procedures with midline closure (18%). (5) A similar procedure is the Limberg flap, which uses a rhomboidal excision and movement of a flap into the cleft. The area from which the tissue is moved is sutured closed in a manner similar to z-plasty.5

In spite of the successes touted in studies of flap procedures, a Cochrane database study showed that excision with secondary intention has the best outcome statistically. Incision and drainage was found to have the worst rate of complications and recurrence, and excision with closure was found to have intermediate results. (1,6) One specific method of insuring that the wound does not prematurely close is unroofing and marsupialization. After the infected tissue is removed, tissue is sutured such that the wound must granulate in and reepithelialize. Compared with rhomboid excision and Limberg flap, unroofing and marsupialization required longer healing times, but patients spent less time hospitalized, and had faster functional recovery and fewer complications. (7)

Post-op care

Hair removal has been suggested as a means of decreasing the risk of recurrence. However, results are inconsistent. Shaving and depilatories do not appear to be as effective as laser hair removal. In one study, none of the patients who received Nd:YAG laser hair removal experienced recurrence, compared with a control group that experienced 70% recurrence within two years. (8) On the other hand, those who used shaving in an effort to decrease risk of recurrence instead had a greater recurrence rate (30%) compared with control subjects (20%). (9)

Research into best practices for healing post-op are lacking. In general, one expects patients to return to previous function within four weeks following surgical closure and eight weeks following excision with closure by secondary intent. However, closure of such wounds may lead to recurrence and referral of a patient to physical therapy for debridement due to the persistence of purulence or necrosis. In the cases of patients who received excisional surgery, examination of the wound is very straightforward. Visual examination, palpation around the wound and probing with a cotton-tipped applicator are easily performed with this type of open wound. However, in the case of an I & D wound, visualization of the wound bed is more difficult. Use of a light and magnifier is somewhat beneficial, but meticulous palpation of the wound margins and probing become very important as visualization becomes limited by intact edges over the wound. Sinus tracts can be multiple and quite long, especially in those who have received multiple I & D procedures.

Early on, daily treatment is frequently necessary, for perhaps up to 1-2 weeks. This may be followed by treatment every 2-3 days for an additional 2-3 weeks. Treatment should continue until the patient has a clean stable wound. A plan of care should include selective debridement with some combination of sharp instruments, pulsed lavage, or use of a low frequency ultrasonic debridement device. In addition to debridement of visible necrotic tissue, pulsed lavage with a flexible tip is useful to clear sinus tracts, which can be multiple and quite long. Patient education includes dressing changes, cleansing between visits and determining whether the patient needs to call his/her physician or go to an emergency department. Evidence of a clean stable wound includes a red wound bed, the quality and quantity of drainage on removed dressings, clear effluent from pulsed lavage, and absence or, at least, significant regression of any induration, bogginess, erythema, or warmth surrounding the wound.

No recommendations regarding topical medications or type of dressing can be supported by the literature. Packing with iodoform initially, and alginate or hydrofiber later as the bioburden diminishes seems reasonable. The use of antibiotics and type of dressing do not appear to have any effect on healing rate, (10) but use of saline gauze has been shown to be more painful. (10) Most patients respond well to this plan of care and can be discharged with a clean stable wound that can be managed by the patient and physician within 2-3 weeks. Some patients will have very complex wounds with difficult to reach tracts and may need additional I & D of these tracts. In patients who were not referred to physical therapy, rate of healing is quite variable. In one particular study, only 60% of wounds were closed within 12 weeks post-op. (10) Return to work may vary with the patient's response to treatment, physician preferences, and the patient's particular duties at work.


Patients with surgical treatment of pilonidal cysts are frequently referred to physical therapy for management of their wounds. Although theories abound, the etiology and pathogenesis are not understood. Risk factors and age of those developing these infections point to the role of hair, shape of the natal cleft, and possibly trauma as causative. Wounds treated with I & D are more difficult to manage. They may close prematurely or continue to form tracts. Thorough examination of the wound for sinus tracts extending subcutaneously is imperative to avoid a protracted episode of care. A combination of sharp debridement, pulsed lavage and patient education along with meticulous examination may allow faster return to function. Excisional wounds are less likely to become complicated, but the prudent therapist will continually monitor these wounds for complications as well.

Glenn Irion, PhD, PT, CWS is Associate Professor of Physical Therapy at the University of South Alabama in Mobile. He is Editor of Acute Care Perspectives and author of the textbook Comprehensive Wound Management and co-editor of the textbook Women's Health in Physical Therapy. He maintains a wound management practice at Mobile Infirmary Medical Center.


(1.) Doll D, Krueger CM, Schrank S, Dettmann H, Petersen S, Duesel W. Timeline of recurrence after primary and secondary pilonidal sinus surgery. Dis Colon Rectum. 2007 Nov;50(11):1928-34.

(2.) Akinci OF, Kurt M, Terzi A, et al. Natal cleft deeper in patients with pilonidal sinus: implications for choice of surgical procedure. Dis Colon Rectum. 2009 May;52(5):1000-2.

(3.) Doll D, Matevossian E, Wietelmann K, et al. Family history of pilonidal sinus predisposes to earlier onset of disease and a 50% long-term recurrence rate. Dis Colon Rectum. 2009; 52(9):1610-5.

(4.) Mentes O. Oysul A, Harlak A, et al. Ultrasonography accurately evaluates the dimension and shape of the pilonidal sinus. Clinics (Sao Paulo). 2009 Jun;64(3):189-92.

(5.) Can MF, Sevinc MM, Yilmaz. Comparison of Karydakis flap reconstruction versus primary midline closure in sacrococcygeal pilonidal disease: results of 200 military service members. Surg Today. 2009;39(7):580-6.

(6.) McCallum I, King PM, Bruce J. Healing by primary versus secondary intention after surgical treatment for pilonidal sinus. Cochrane Database Syst Rev. 2007 Oct 17;(4):CD006213

(7.) Karakayali F, Karagulle E, Karbulut Z, et al. Unroofing and marsupialization vs. rhomboid excision and Limberg flap in pilonidal disease: a prospective, randomized, clinical trial. Dis Colon Rectum. 2009;52(3):496-502.

(8.) Badawy EA, Kanawati MN. Effect of hair removal by Nd:YAG laser on the recurrence of pilonidal sinus. J Eur Acad Dermatol Venereol. 2009 Aug;23(8):883-6.

(9.) Petersen S, Wietelmann K, Evers T, et al. Long-term effects of postoperative razor epilation in pilonidal sinus disease. Dis Colon Rectum. 2009;52(1):131-4.

(10.) Stewart A, Donoghue J, Mitten-Lewis S. Pilonidal sinus: healing rates, pain and embarrassment levels. J Wound Care. 2008;17(11):468-70,472,474.
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Author:Irion, Glenn
Publication:Acute Care Perspectives
Article Type:Report
Geographic Code:1USA
Date:Sep 22, 2009
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