Pilonidal Sinus

Pilonidal disease most often affects young adults and is more common in men. It develops when loose hairs penetrate the skin in the natal cleft, the groove between the buttocks, and trigger a reaction that forms small pits and tracts under the skin. Friction, prolonged sitting and coarse body hair all contribute.

The condition runs a spectrum. Some people have a single episode of pain and swelling that settles. Others develop recurrent abscesses, or one or more small openings that discharge intermittently and never fully heal. Once the disease is recurrent, it usually continues until it is treated definitively.

Symptoms depend on whether the sinus is quiet, inflamed or infected.

Severe pain with fever, or a rapidly enlarging painful swelling, suggests an acute abscess and should be assessed promptly.

• Pain and tenderness at the top of the cleft between the buttocks, worse with sitting.
• A small pit or pits in the midline of the cleft, sometimes with hairs protruding.
• Intermittent discharge of fluid or pus, often staining underwear.
• Recurrent swelling or a painful lump, which may burst and drain before settling again.
• An acutely painful, red, hot swelling when an abscess forms.

The diagnosis is usually clear from the history and a gentle examination. The characteristic findings are midline pits in the natal cleft, sometimes with surrounding swelling, scarring or discharge.

Assessment establishes how extensive the disease is, whether there is an active abscess, and what previous treatment has been tried. This guides the choice between simple measures, a limited procedure and more definitive surgery. Tests are not usually needed; imaging is reserved for unusual or recurrent cases where the extent of the tracts is uncertain.

Treatment is matched to how the disease is behaving. Mild disease with a single settled episode may be managed with hair removal and observation. An acute abscess usually needs a small drainage procedure, performed promptly to relieve pain.

For recurrent or persistent disease, surgery is recommended. Limited procedures remove the midline pits and clean the tracts through small incisions, and suit less extensive disease. More extensive or recurrent disease is better treated by excising the affected tissue and reconstructing the area so that the scar sits away from the midline and the cleft is flattened, which lowers the chance of recurrence.

The reasoning behind the recommended approach, the alternatives and the expected benefits and risks are discussed in full before any decision is made.

Recovery depends on the procedure performed. Limited procedures usually involve a short period of wound care and a return to light activity within one to two weeks. Excision with reconstruction takes longer, and comfortable sitting can take several weeks.

Where the wound is left open to heal from the base, or where a reconstructed wound is at higher risk of breaking down, a negative pressure wound dressing (often called a VAC dressing) may be used. This is a sealed foam dressing connected to a small portable pump that applies gentle suction to the wound. It removes fluid, reduces swelling, keeps the wound clean and encourages new tissue to form, which can shorten healing time and reduce the number of dressing changes. The dressing is changed every few days, either in hospital or through a home nursing service, and the pump is small enough to carry during normal daily activity. Whether it is appropriate depends on the type of surgery and the wound, and it is discussed as part of your recovery plan.

Wound care instructions, review appointments and advice on returning to work, driving and exercise are provided for your specific procedure. Keeping the cleft free of hair during healing, and often longer term, is an important part of reducing recurrence.