Pilonidal sinus

What is a pilonidal sinus?

This is a small, enclosed pit located under the skin. It's most commonly found in the cleft between the buttocks and is caused by a hair that penetrates the skin. Barbers and hairdressers may also get them between their fingers when a hair penetrates the skin here.

Symptoms

Most people are unaware they have a pilonidal sinus until it causes them trouble. Infection is the most likely problem to have occurred if the area becomes uncomfortable and sore.

Causes and risk factors

Men develop them more often than women, especially those men with a large amount of body hair (especially around the buttocks). They're more common in younger adults, too, as well as those whose jobs require them to sit down for long periods (for example, in World War II, so many US soldiers who drove jeeps developed the problem that it became known as Jeep Disease). There's also often a family history of the condition.

Quite why it happens isn't entirely clear. When they occur in the cleft between the buttocks, one popular explanation is that there's a developmental defect in the direction that the hair grows - that is, the hair grows inwards rather than outwards.

Treatment and recovery

Soaking the area in warm water will relieve discomfort, as will painkillers and anti-inflammatory medication. Antibiotics are needed to treat the infection and, if an abscess develops, this may need surgical drainage in hospital.

Despite these treatments, 40 per cent of people find the problem recurs and will require surgery to remove the sinus for good.

The pilonidal sinus can be removed with an operation in hospital and this usually prevents problems with infection arising in the future. But recovery from surgery can be quite slow and painful as the wound has to be packed and re-dressed regularly by a nurse while it heals, during which time it can be very uncomfortable, especially while someone is sitting down.