PILONIDAL SINUS EXCISION

Pilonidal Sinus Disease

Pilonidal sinus disease is a tract with an opening on the skin leading to a collection of hair. It most commonly occurs in the natal cleft(in the midline between the buttocks) but it can also occur elsewhere - eg in hands(especially in barbers) and around the belly button.

How Pilonidal Sinus Develops

The natal cleft is often moist. The hair shafts (which under the microscope look like barbs) drill into the soft moist skin when one sits(the buttocks can also create a suction type effect - suckiing in the hair deeper). This may be then lead to localized inflammation(folliculitis) which further weakens the skin. Over time a nest full of hair forms under the skin. This may be connected to the outside skin by a small sinus tract.

Interestingly, the sinus may also be congenital(present from birth) in some people. This may explain why people who are not hairy develop pilonidal sinus disease too.

Complications

An abscess can develop when an infection forms within this nest of hair and the tract is not able let the pus drain out. This can be very painful. In addition, it may be complicated by sepsis (with high fever) and surrounding skin infection(cellulitis).

The emergency treatment for this is to drain the abscess - it is important that the incision is placed to one side of the midline(this is so that in future when curative surgery is performed, the scar from the incision can be excised as well)

Surgery

The principles of surgery for pilonidal sinus disease is :

(i) To excise the sinus tract and the nest of hair

(ii) To leave a scar away from the midline to reduce the risk of recurrence

(iii) To make the natal cleft shallower to have less chance for hair to reaccumulate or be sucked inwards

The operation involves:

1. Marking out the area prior to making the incisions and putting in local anaesthetic around the area

2. Excising the sinus tract and the nest of hair- this is identified by prior iinjection with blue dye. This is done in a way which will leave the resulting scar away from the midline

3. Raising a local flap of skin to cover to allow closure of the wound - ensuring that the wound stays away from midline and the natal cleft becomes shallower

(This operation is known also as the Modified Karydakis operation)

Other options:

1. Direct excision and closure - but this will leave a scar in the midline and has a high recurrence rate (20-30% - info from the Australian Colorectal Society website)

2. Excision and closure with other types of flaps including rhomboid flaps- again the principle is the same

3. Excision and wound left open - this will take months to heal.

4. Excision of pit, removal of hair and cleaning of the tract - this is a smaller operation but has a high recurrence rate.

Risks of Surgery

1. Recurrence - the Modified Karydakis has a very low recurrence rate(1-3%).

2. Bleeding - there is a risk of a small amount of bleeding and bruising. During the operation, any bleeding blood vessels would be cauterized to reduce the risk of a haematoma developing after the operation.

3. Wound infection / breakdown - this would need treatment with antibiotics and occassionally surgical drainage. This may lead to an area that would take longer to heal. To reduce the risk, intravenous antibiotics is given at the time of surgery.

4. Pain in the wound as with any other cuts.

Useful link: www.pilonidal.org

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