Understanding pilonidal sinus
A pilonidal sinus is a small tunnel or cavity in the natal cleft — the groove just above the buttocks, over the tailbone. It develops when loose hairs are driven into the skin by the constant friction and movement of the area. The body treats the buried hair as a foreign body, and a chronic infected cavity forms around it.
It affects young adults far more than any other group, is more common in men, and is strongly associated with prolonged sitting, a deep natal cleft, coarse body hair, obesity and sweating. Drivers, IT professionals, students and people who sit for long stretches are disproportionately affected — which is why it was once known as “jeep driver’s disease”.
Symptoms range from an intermittent painless pit that occasionally discharges, to a full-blown acute abscess with severe pain, swelling and fever that makes sitting impossible. Many patients have a history of repeated abscess drainages over several years.
The historical treatment — wide excision leaving the wound open to heal by itself — cures the sinus but leaves a large wound that takes two to three months of daily dressings to heal, with significant time off work. Modern minimally invasive options have changed this substantially. Laser closure (SiLaC) and endoscopic treatment (EPSiT) deal with the cavity through a small opening, with far shorter healing times. For complex or recurrent disease, flap procedures that flatten the cleft and move the scar off the midline give the lowest recurrence rates.
Types & classification
A small midline dimple found incidentally, with no infection. Often needs only hygiene and hair control, with monitoring.
A painful, swollen, red collection needing prompt drainage for relief. Definitive treatment follows once the infection settles.
A persistent cavity with one or more openings, discharging on and off for months or years. The commonest presentation for elective surgery.
Multiple tracks, wide involvement, or disease returning after previous surgery. Usually best treated with a flap procedure.
Symptoms & causes
Symptoms to look for
- Pain and swelling in the cleft just above the buttocks
- Discharge of pus or blood, sometimes with an odour
- One or more small pits or openings in the midline
- Visible hair protruding from an opening
- Pain on sitting, driving or lying on the back
- Fever and severe pain when an abscess forms
- Repeated episodes settling and recurring over months or years
Common causes & risk factors
- Loose hair being driven into the skin of the natal cleft by friction
- Prolonged sitting — driving, desk work, long study hours
- A deep natal cleft and coarse, dense body hair
- Obesity and excessive sweating in the area
- Poor local hygiene, or conversely aggressive shaving that leaves sharp hair stubble
- Local trauma or repeated pressure
- A family tendency, and being aged between fifteen and forty
When to see a surgeon
- Pain or swelling over the tailbone, especially if recurring
- Any discharge from a pit or opening in the natal cleft
- A painful swelling with fever — this is an abscess and needs drainage soon
- A sinus that has returned after previous surgery
- A pit noticed incidentally, even without symptoms, so hair control can be started early
How it is diagnosed
The characteristic midline pits, often with a hair visible, make the diagnosis straightforward in most cases.
To assess how far the cavity extends and whether there are secondary openings off the midline.
Occasionally used to define the extent of a complex or recurrent cavity before surgery.
Reserved for extensive recurrent disease, or where an anal fistula needs to be excluded as an alternative diagnosis.
Blood counts, sugar and inflammatory markers where there is active infection or repeated recurrence.
Treatment options
The appropriate option depends on your diagnosis, examination and general health. Your clinician will explain the benefits and risks of the available approaches.
For an acute abscess, incision and drainage under local or short anaesthesia gives immediate relief. Definitive surgery is planned separately once the inflammation has settled.
A laser fibre is introduced into the cleaned cavity and withdrawn slowly, sealing the tract from within. A small wound, no packing, minimal downtime and a rapid return to sitting and work.
A fine endoscope is passed into the sinus so the cavity is visualised directly, all hair and debris removed, and the lining ablated under vision. Excellent for complex tracks.
The midline pits are excised through tiny incisions and any lateral cavity drained off the midline. Minimal tissue removal, quick recovery, suited to limited disease.
The sinus is excised and the wound closed. Faster healing than an open wound, but a midline closure has a higher recurrence rate — which is why off-midline techniques are preferred.
The sinus is excised and healthy tissue rotated in, flattening the cleft and placing the scar away from the midline. The lowest recurrence rate for extensive or recurrent disease.
Reliable and still occasionally necessary in severe disease, but involves a large wound and eight to twelve weeks of dressings. Now used selectively rather than routinely.
Preparing for treatment
- Hair in the natal cleft is trimmed or clipped before surgery
- Any active infection is settled with drainage and antibiotics first
- Standard blood tests, sugar control and anaesthetic review
- Six hours fasting before anaesthesia
- Arrange a few days where you can avoid prolonged sitting
- Plan for long-term hair removal — laser hair reduction is the single most effective way to prevent recurrence
The procedure, step by step
- AnaesthesiaSpinal, general or in limited disease local anaesthesia with sedation.
- Identification of the tracksAll pits and tracks are identified and probed; dye may be used to reveal branches that are not obvious.
- Clearing the cavityHair, debris and unhealthy granulation tissue are removed completely — leaving hair behind is a common cause of recurrence.
- Laser ablation or endoscopic ablationThe laser fibre or endoscopic electrode is drawn along the tract, destroying the lining and shrinking the cavity so it collapses and seals.
- Pit excisionThe small midline openings are excised so they cannot admit hair again.
- Closure or flapFor laser and EPSiT, the small wound is left to close naturally. In flap surgery, tissue is rotated to flatten the cleft, with the scar placed off the midline.
- Dressing and drainA light dressing, and a small drain in flap procedures for the first day or two.
Recovery timeline
- Day 0 – 1Home the same day after laser or EPSiT; one night after a flap procedure. Avoid sitting directly on the area; use a cushion.
- Days 2 – 7Wound cleaned daily. Mild discharge is expected. Most patients return to desk work within this week after laser treatment.
- Weeks 2 – 4The wound closes progressively. Flap sutures are removed around day ten to fourteen. Prolonged sitting is gradually resumed.
- Weeks 4 – 8Healing completes in most laser cases. Driving and gym resume once cleared.
- Long termRegular hair removal from the natal cleft, keeping the area clean and dry, weight control and avoiding uninterrupted sitting are what prevent recurrence. This aftercare matters as much as the operation.
Benefits of this approach
- A small wound instead of a large open excision
- No prolonged daily packing and dressing
- Return to sitting and desk work within days rather than weeks
- Day-care procedure for most patients
- Significantly less pain than open excision
- Repeatable if a track persists, with other options still available
- Better cosmetic result and, with off-midline flaps, a lower recurrence rate
Risks & possible complications
Every operation carries risk, and you should hear about it before you consent rather than afterwards. These are discussed individually at consultation in the context of your own health.
- Recurrence — the main issue in pilonidal disease, and strongly linked to whether hair control is maintained afterwards
- Wound infection or a collection under a flap
- Delayed healing, especially in smokers, diabetics and obese patients
- Seroma under a flap, occasionally needing aspiration
- Some patients need a second procedure if a track persists
- Numbness around the scar after flap surgery
What affects the cost
- Extent of the sinus — single track versus complex, multi-track or recurrent disease
- Technique used: laser, EPSiT, pit picking, primary closure or flap
- Whether an abscess needs draining first as a separate procedure
- Anaesthesia type and length of stay
- Dressings and follow-up over the healing period
- Covered by most insurance policies; the team assists with authorisation