A pilonidal sinus (PNS) is a small abnormal tunnel (sinus tract) that forms in the skin of the natal cleft (the groove between the buttocks, just above the anus). It often contains hair, debris, and pus, and can get infected repeatedly.

Causes / Risk Factors

• Ingrown hair penetrating the skin → foreign body reaction → sinus formation
• Prolonged sitting (drivers, students, office workers)
• Local trauma or friction
• Obesity
• Excessive body hair (especially coarse hair)
• Poor hygiene
• More common in young men (15–35 years)

Symptoms

• Small pit/opening in the natal cleft
• Pain and swelling in the sacrococcygeal region
• Discharge of pus or blood (foul smelling) from the sinus opening
• Recurrent abscess formation
• Tenderness and difficulty in sitting

• Acute pilonidal abscess – painful swelling with pus collection
• Chronic pilonidal sinus – persistent sinus with discharge, intermittent pain
• Recurrent pilonidal sinus – after inadequate healing or incomplete surgery

Treatment

Does not heal on its own – surgical treatment is needed.

1. Conservative (temporary relief)

• Good hygiene & regular shaving/laser hair removal around natal cleft
• Sitz baths
• Antibiotics for acute infection

2. Surgical

• Incision & drainage – for acute abscess
• Kshar Sutra Application
• Laser Ablation
• Excision with primary closure – sinus tract is removed and wound closed; quicker healing but higher recurrence
• Excision with open healing (marsupialization) – wound left open to heal by granulation; lower recurrence, but slower healing
• Cleft lift or flap procedures (Karydakis flap, Limberg flap) – for recurrent/complex cases, flatten the natal cleft to prevent recurrence

Complications

• Recurrent infection/abscess
• Chronic discharging sinus
• Rarely, malignant transformation (squamous cell carcinoma) in long-standing untreated cases