What is pilonidal sinus and what causes it?

Pilonidal sinus is a chronic infection of the skin in the region of the buttock crease (Figure 1). The condition results from a reaction to hairs embedded in the skin, commonly occurring in the cleft between the buttocks. The disease is more common in men than women and frequently occurs between puberty and age 40. It is also common in obese people and those with thick, stiff body hair.

What are the symptoms?

Symptoms vary from a small dimple to a large painful mass. Often the area will drain fluid that may be clear, cloudy or bloody. With infection, the area becomes red, tender, and the drainage (pus) will have a foul odour. The infection may also cause fever, malaise, or nausea.

There are several common patterns of this disease. Nearly all patients have an episode of an acute abscess (the area is swollen, tender, and may drain pus). After the abscess resolves, either by itself or with medical assistance, many patients develop a pilonidal sinus. The sinus is a cavity below the skin surface that connects to the surface with one or more small openings or tracts. Although a few of these sinus tracts may resolve without therapy, most patients need a small operation to eliminate them.

A small number of patients develop recurrent infections and inflammation of these sinus tracts. The chronic disease causes episodes of swelling, pain, and drainage. Surgery is almost always required to resolve this condition.

How is pilonidal disease treated?

The treatment depends on the disease pattern. An acute abscess is managed with an incision and drained to release the pus, and reduce the inflammation and pain. This procedure is performed as an emergency in hospital under general anaesthesia.  The patient is discharged either on the same or following day. A chronic sinus may persist after the abscess cavity has healed and this usually needs to be excised or surgically opened.

Complex or recurrent disease must be treated surgically. Procedures vary from unroofing the sinuses to excision (Figure 2) and possible closure with flaps. Larger operations require longer healing times. If the wound is left open, it will require dressing or packing to keep it clean. Although it may take several weeks to heal, the success rate with open wounds is higher. Closure with flaps is a bigger operation that has a higher chance of infection; however, healing and recovery is quicker. Mr Abulafi or a member of his team will discuss these options with you and help you select the appropriate operation.

What care is required after surgery

If the wound can be closed, it will need to be kept clean and dry until the skin is completely healed. If the wound must be left open, dressings or packing will be needed (usually by the district or practice nurse) to help remove secretions and to allow the wound to heal from the bottom up.

After healing, the skin in the buttocks crease must be kept clean and free of hair. This is accomplished by shaving or using a hair removal agent every two or three weeks until age 30. After age 30, the hair shaft thins, becomes softer and the buttock cleft becomes less deep.

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