A pilonidal sinus is a small pit that occurs at the bottom of the tailbone or coccyx that can become infected and filled with pus. Pilonidal means a ‘nest of hairs’.

Sinus tract is a abnormal narrow tunnel in the body which goes between a focus of infection in deeper tissues to the skin surface. This channel discharges pus occasionally on the skin,

Pilonidal tract is a sinus tract which contains hairs. It appears under the skin between the buttocks (the natal cleft) a short distance above the back passage (anus). It goes in a vertical direction between the buttocks.

However, in some rare cases, pilonidal sinus can appear in other parts of the body.



What causes a pilonidal sinus?
There are no clear reasons for the incidence of pilonidal sinus, Some theories say that people were born with this minor abnormality between the buttocks. Therefore, it can be inherited. In this condition, the hairs grow into the skin rather than outwards.

Another theory says that pilonidal sinus occurs due to the development of skin dimples in the skin between the buttocks. Presumably, they develop as a result of local pressure which damages the hair follicles. Growing hair in the natal cleft may get pushed into the skin pits because of local pressure.

Once hair fragments become ‘stuck’ in the skin they irritate it and cause inflammation. Inflamed skin quickly becomes infected and so a recurring or persistent infection tends to develop in the affected area. This kind of infection causes the sinus to develop which often contains broken pieces of hair.

Who gets pilonidal sinus?
Certain factors increase the risk of developing the condition and include:

A job involving a lot of sitting (a sedentary occupation)
Being overweight (obesity)
A previous persistent irritation or injury to the affected area
Having a hairy, deep natal cleft
A family history of the condition
What are the symptoms of pilonidal sinus?
Rapid-onset (acute) symptoms
The patient notices increasing discomfort and swelling over a number of days and the pain may be severe by the time of presentation. On examination there is a localised fluctuant swelling in the midline of the natal cleft with overlying cellulitis. The area is exquisitely painful to touch and often simply the act of separating the buttocks to examine the area is intolerable for the patient.

Persistent (chronic) symptoms
This is common for patients to present with chronic pain and discharge, often with a history of up to two years. On examination a single, or occasionally, multiple sinuses may be seen. Tufts of hair or other debris, such as clothing fibres, are often visible arising from the sinus. Localised edema, swelling and inflammation may be present masking the underlying sinus.



What is the treatment for pilonidal sinus?
If you have no symptoms
If you have no symptoms then you should clear the affected area of hairs by shaving or other means of hair removal. Also, keep the area clean with proper personal hygiene.

If you have rapid-onset (acute) symptoms
If you have an infection then you should take antibiotics. Painkillers (such as paracetamol and/or ibuprofen) may be very helpful to relieve the pain. Maybe you will need to have an emergency operation to puncture (incise) and drain the ball of pus with surrounding skin infection (abscess).

3. If you have persistent (chronic) symptoms
Generally, an operation is recommended.. The options include the following:

Wide excision and healing by secondary intention. This operation consists of cutting out the sinus but also cutting out a wide margin of skin which surrounds the sinus. The wound is left open to heal by natural healing processes (healing by ‘secondary intention’). This usually requires several weeks of regular dressing changes until it heals completely. The advantage of this method is that all inflamed tissue is removed and the chance of the condition coming back (recurrence) is low.

Excision and primary closure. This means removing the section of skin which contains the sinus. This is done by cutting out an oval-shaped (ellipse) flap of skin either side of the sinus, which takes out the sinus, and stitching together the two sides of the ellipse. After this the wound heals very The risk of a recurrence or of developing a wound infection after the operation is higher than the above procedure.

A plastic surgery technique. Sometimes, when the sinus recurs or is extensive, plastic surgery may be advised to remove the sinus and refashion the nearby skin.

After any operation
Surgeons recommend keeping the area free of hair growing by shaving regularly, or by other methods to remove the hair. This prevents the coming back (recurring) of the problem.