Pilonidal Sinus
A small tunnel containing hair and debris near the tailbone that tends to become infected and painful.
A pilonidal sinus is a small tunnel or cavity in the skin at the top of the buttock cleft, near the tailbone, that often traps hair and debris. It can become infected, causing a painful swelling and discharge. Treatment ranges from drainage of an abscess to minimally invasive laser surgery for a lasting cure.
A pilonidal sinus develops in the crease at the top of the buttocks, near the tailbone. It is especially common in young adults, particularly men, and in people who sit for long periods. Although it can be uncomfortable and prone to repeated infection, modern minimally invasive techniques now allow it to be treated with small wounds and a quicker return to normal life.
पाइलोनिडल साइनस भनेको ढाडको तल पुच्छरको हड्डी नजिक छालामा बन्ने सानो नाली हो, जसमा कपाल र फोहोर जम्मा भई संक्रमण, दुखाइ र पिप बग्ने हुन्छ; लेजर शल्यक्रियाबाट न्यून चिरामा उपचार गर्न सकिन्छ।
Understanding Pilonidal Sinus
A pilonidal sinus is a small tract or pocket under the skin in the natal cleft — the groove between the buttocks near the tailbone. The word means \"nest of hair\", and the condition is thought to begin when loose hairs and skin debris are driven into the skin, triggering a foreign-body reaction that forms a cavity. Friction, sitting and moisture in the area encourage this process.
The sinus may stay quiet for long periods, or it may become blocked and infected — forming a painful abscess that discharges pus and fluid. Repeated infections can lead to several openings and a chronic, discharging sinus.
Symptoms
- Pain, swelling and redness in the crease above the buttocks
- A tender lump near the tailbone that may come and go
- Discharge of pus or blood, sometimes foul-smelling
- One or more small openings (pits) in the skin of the cleft
- Visible hair protruding from an opening
- Fever and feeling unwell during an active infection
Causes & risk factors
- Ingrown or loose hairs pushed into the skin of the cleft
- Prolonged sitting (drivers, students, office workers)
- Friction and pressure over the tailbone area
- Excess body hair and a deep natal cleft
- Being overweight and poor local hygiene
- A family tendency and being a young adult male
Possible complications
- Recurrent painful abscesses in the same area
- A chronic, non-healing sinus with persistent discharge
- Multiple tracts and openings that widen over time
- Spread of infection to surrounding skin (cellulitis)
- Slow wound healing and recurrence after wide open surgery
How it is diagnosed
A pilonidal sinus is usually diagnosed by simply examining the skin over the tailbone, where the characteristic pits, openings and any hair are visible. During an active infection, the area is tender, red and swollen. Dr. Sujan Shrestha assesses the extent of the tracts to plan treatment; imaging is rarely needed for straightforward cases but may help map complex or recurrent disease.
Treatment options
If there is an acute abscess, the first step is usually to drain it and relieve the pain, along with antibiotics if infection is spreading. Keeping the area clean and free of loose hair (with hygiene measures and hair removal) helps prevent flare-ups. A quiet, uninfected sinus still needs definitive treatment to prevent it from recurring, and several techniques are available depending on its size and complexity.
Surgical treatment
Dr. Sujan Shrestha offers minimally invasive laser treatment for pilonidal sinus (such as laser sinus ablation), in which a fine laser fibre is used to clean and seal the tract through a tiny opening. This avoids the large, slow-healing wounds of traditional wide excision, so patients usually have less pain and a faster recovery. For more extensive disease, procedures such as pit-picking or a flap technique that flattens the cleft may be recommended to lower the chance of recurrence.
Recovery & aftercare
Recovery after minimally invasive laser treatment is generally quick, with most patients going home the same day and returning to normal activities within a short time. Keeping the area clean, removing hair regularly, avoiding prolonged sitting during early healing, and attending follow-up are important. Traditional open surgery involves a larger wound that heals more slowly and needs regular dressing care.
When to see a doctor
See a doctor if you notice a painful lump, swelling or discharge in the crease above your buttocks, or a persistent opening that leaks fluid. Seek prompt care if there is increasing pain, spreading redness or fever, which suggests an abscess that may need urgent drainage.
Frequently asked questions
It is thought to form when loose hairs and skin debris are pushed into the skin of the buttock cleft, triggering a reaction that creates a small cavity. Prolonged sitting, friction, excess hair and a deep cleft all increase the risk.
An abscess can be drained and hygiene measures may keep it quiet, but an established sinus tends to recur without definitive treatment. A procedure is usually needed to clear the tract and prevent repeated infections.
Laser treatment cleans and seals the tract through a very small opening, avoiding the large open wound of traditional wide excision. This usually means less pain, a smaller scar and a faster return to normal activities.
Keeping the area clean and dry, removing hair regularly from the cleft, avoiding long periods of sitting where possible, and maintaining a healthy weight all help reduce the risk of recurrence after treatment.
No. A pilonidal sinus sits over the tailbone, not at the anus, so it is a separate condition from piles or an anal fistula. It does, however, share the theme of an infected tract that benefits from minimally invasive treatment.
Get a clear answer from a specialist
Dr. Sujan Shrestha (MBBS, MS, MCh) offers evidence-based, minimally invasive care for pilonidal sinus and the full range of GI conditions.