Overview
Definition:
A pilonidal sinus is an acquired condition characterized by a chronic inflammatory condition in the natal cleft, typically containing hair fragments and debris, leading to the formation of sinuses or abscesses
Excision with flap reconstruction, particularly the Karydakis technique, aims for complete removal of the sinus and surrounding diseased tissue with primary closure using a lateralized flap to reduce recurrence.
Epidemiology:
It predominantly affects young adults, with a male predominance (3:1 to 4:1)
Incidence is higher in Caucasians
Risk factors include obesity, deep natal cleft, sedentary lifestyle, and thick hair growth.
Clinical Significance:
Pilonidal sinus disease is a common surgical problem causing significant morbidity, pain, and disability
Recurrence rates are high with traditional open excision methods
The Karydakis flap technique offers improved outcomes with lower recurrence rates and faster healing, making it a critical procedure for surgical residents to understand and master for DNB and NEET SS preparation.
Clinical Presentation
Symptoms:
Acute presentation often includes severe pain and swelling in the natal cleft, suggestive of an abscess
Chronic symptoms include recurrent discharge (serous, purulent, or bloody), discomfort, and pain, especially with prolonged sitting
A palpable lump may be present
Recurrent infections can lead to tunneling and multiple external openings.
Signs:
A midline dimple or pits in the natal cleft, often with protruding hairs
Palpation may reveal tenderness, fluctuance (if abscessed), or induration
External openings of sinus tracts are visible, often with surrounding inflammation or granulation tissue
Edema and erythema may be present if acutely infected.
Diagnostic Criteria:
Diagnosis is primarily clinical, based on characteristic symptoms and physical examination findings
There are no formal diagnostic criteria
however, the presence of a midline natal cleft sinus tract with associated hair, discharge, or recurrent infection is pathognomonic.
Diagnostic Approach
History Taking:
Key history points include onset and duration of symptoms, nature of discharge, presence of pain, previous treatments (conservative or surgical), history of trauma to the area, and occupational/lifestyle factors (e.g., prolonged sitting, physical labor)
Inquire about fever or systemic symptoms if acute infection is suspected.
Physical Examination:
A thorough examination of the natal cleft is essential
Inspect for dimples, pits, sinus openings, hair extrusion, erythema, and swelling
Palpate for tenderness, induration, and fluctuance
Assess the extent of the sinus tract if possible
Avoid aggressive palpation of acutely inflamed or abscessed areas.
Investigations:
Generally, no investigations are required for a typical diagnosis
In complex cases, recurrent disease, or suspected malignancy (rare), imaging like MRI can delineate the extent of tracts and identify associated pathology
A complete blood count (CBC) may be useful to assess for signs of acute infection.
Differential Diagnosis:
Differential diagnoses include hidradenitis suppurativa, anal fistula, coccygeal osteomyelitis, superficial folliculitis, sebaceous cysts, and spinal dermoid sinus
Distinguishing features involve the specific location (natal cleft), characteristic hair findings, and pattern of discharge.
Management
Initial Management:
For acute abscesses, incision and drainage (I&D) are the initial steps
This provides symptomatic relief
Conservative management with local hygiene and antibiotics may be considered for very mild superficial infections or as an adjunct to I&D, but it does not address the underlying pathology.
Medical Management:
Antibiotics are primarily used to treat acute infections or cellulitis associated with pilonidal sinus
Broad-spectrum antibiotics targeting skin flora (e.g., Staphylococci and Streptococci) are typically prescribed
Examples include cephalexin 500 mg orally four times daily or clindamycin 300 mg orally three times daily for 7-10 days
This is usually an adjunct to surgical drainage for abscesses.
Surgical Management:
The Karydakis flap is the gold standard for definitive treatment
It involves wide excision of the sinus, subcutaneous tissue, and any tracts, extending to healthy tissue
The natal cleft is then flattened by excising a portion of the skin and subcutaneous tissue from the affected side and creating a rotation-advancement flap from the contralateral side to close the defect
This technique aims to eliminate the deep natal cleft predisposing to recurrence.
Postoperative Care:
Wound care is crucial
Patients are advised to keep the area clean and dry, avoiding prolonged sitting for the initial period
Pain management is essential
Antibiotics may be prescribed prophylactically or if signs of infection develop
Mobilization is encouraged to prevent deep vein thrombosis
Regular follow-up is required to monitor wound healing and detect any signs of recurrence.
Complications
Early Complications:
Wound infection, dehiscence, seroma formation, hematoma, flap necrosis, and delayed wound healing
Pain is a significant early complication requiring adequate analgesia.
Late Complications:
Recurrence of the pilonidal sinus disease is the most significant late complication, occurring more frequently with less radical excision techniques
Chronic pain and contour deformities are also possible.
Prevention Strategies:
Meticulous surgical technique with wide excision, complete removal of all sinus tracts, and effective flap closure are paramount
Postoperative wound care, hygiene, and avoidance of prolonged sitting in the early period help prevent complications and recurrence
Hair removal in the natal cleft area post-healing is often recommended.
Prognosis
Factors Affecting Prognosis:
The success rate is heavily dependent on the thoroughness of the excision and the technique used
The Karydakis flap has shown significantly lower recurrence rates (typically <5%) compared to simple excision or other flap techniques.
Outcomes:
With successful Karydakis flap surgery, patients can expect a durable cure with minimal risk of recurrence and a satisfactory cosmetic outcome
Most patients return to normal activities within 2-4 weeks.
Follow Up:
Follow-up appointments are scheduled at 1 week, 1 month, and 3-6 months post-operatively, or as needed
The purpose is to monitor wound healing, assess for any signs of infection or recurrence, and ensure patient satisfaction
Long-term self-monitoring for any new symptoms is important.
Key Points
Exam Focus:
Understand the anatomy of the natal cleft and the pathogenesis of pilonidal sinus
Differentiate between acute abscess and chronic disease
Know the indications and contraindications for Karydakis flap
Recognize early and late complications
The Karydakis flap is favored for its low recurrence rate due to elimination of the natal cleft depth.
Clinical Pearls:
Always perform a thorough examination in good lighting
When performing Karydakis, ensure adequate flap mobilization and tension-free closure
Advise patients on the importance of hygiene and avoiding prolonged sitting post-operatively
Remember that recurrence is a significant issue, so radical excision is key.
Common Mistakes:
Incomplete excision of sinus tracts and associated diseased tissue
Failure to create a tension-free closure
Not flattening the natal cleft sufficiently
Inadequate postoperative advice regarding hygiene and activity
Misdiagnosing pilonidal sinus as a simple boil or other perianal pathology.