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What is a pilonidal sinus?

Literally meaning “nest of hairs”, a pilonidal sinus is a cavity under the skin that contains hairs. It most commonly occurs at the top of the natal cleft or more crudely – the butt crack. They can also occur in the belly button, between the fingers and on the sole of the feet. There are many theories as to how they occur. The most logical theory is that the hairs fall off the back and the head and land in the natal cleft. This friction and suction created here results in the hairs drilling under the skin. Over time, a small “pit” develops in the skin and continues to suck hairs into it. These sinuses are often there for years and the patient doesn’t know it. Often however, the sinus develops a bacterial infection. This results in an abscess causing pain, fever and an eventual discharge of pus from the sinus.

Pilonidal sinuses typically occur in people with course hair on their head and back. This is why they are most common in men. Women certainly do however, suffer from this disease. Sufferers tend to have a Middle-eastern or Mediterranean background. They also occur in people who work with hair e.g. hairdressers, horse workers. People that sit all day long are also at risk e.g. professional drivers – as there is a continual suction effect caused by sitting against a seat.

Interestingly, this is a disease of people between 15 and 40. The reasons for this are not known.

Why should a pilonidal sinus be removed?

The decision of remove an asymptomatic sinus is a difficult one and should be decided on a case by case basis. Not all sinuses will become infected. The recover from surgery can be very long, so repair of a sinus that is not causing trouble may not be attractive. Many want a pilonidal sinus repaired before they become infected, because this can occur at a very inconvenient time and has a higher risk of complications.

How is a pilonidal sinus repaired?

The treatment is different for an accidentally found, non infected pilonidal sinus and an inflamed one. An inflamed sinus requires urgent drainage done under general anaesthesia. A cut is made in the skin and the pus is drained. The cavity is then packed with absorbent material. The sinus is then allowed to heal from the bottom up. There will be a raw wound at the top of the natal cleft for many weeks. It will be quite sore for the first week and then you will be able to return to normal life wearing a pad in your underpants. A non inflamed sinus is treated by cutting out the entire sinus and closing the wound again. The aim with this closure is to flatten out the natal cleft and remove the suction effect that caused the sinus.  It is common for these wounds to be infected and the stitches have to be removed early.

What are the complications for pilonidal sinus surgery?

Like any surgery, there are small risks of severe allergy and even death during an anaesthetic. The complications specifically for pilonidal surgery are:

  • Recurrence of the sinus. A considerable number of these sinuses come back, because, aside from shaving the patients head and back regularly, it is impossible to remove the cause. It is common after emergency surgery to need a second procedure.
  • Delayed healing. After removal, these sinuses often heal for a while and then stop. It is common to need further operations to help the healing process and clean out the cavity.
  • Break down of wound. After a planned repair of pilonidal sinus, the wound is closed with stitches. It is very common that these wounds get infected. About 50% of patients will get an infection and the wound will have to be opened. The wound will then be packed and heal from the bottom up.
  • Bleeding: bleeding is very common just after and at any time during the healing process. The healing tissue is very raw and bleeds frequently. Occasionally patients have to return to theatre for this bleeding.

What to expect immediately after surgery

Pain Relief

Every effort will be made to minimize the discomfort. Your surgeon and nurses will be monitoring your level of pain control frequently. Local anaesthetic will be used in the wound and lasts for about 12 hours. You will feel more comfortable lying on your side.

There are two major types of pain relievers after pilonidal surgery.


You will be amazed the power of regular panadol. It will cut down the need for the very strong pain pills. It does not cause constipation. Do not take more than 8 tablets a day.

NSAIDs (Indocid, Brufen, Mobic)

Also excellent pain relievers. They do not cause constipation.Must be used very cautiously in the elderly and those with kidney problems.They may cause stomach ulcers.  If you experience any pain in the upper abdomen you must stop this medication immediately and seek advice. It is uncommon to need anything stronger than panadol after you go home. Try and avoid codeine containing products – like Panadeine and Panadeine Forte, they cause constipation.


It is usual to return to a normal diet within a day of surgery. There are no restrictions. It is very common to feel slightly nauseated for 12 hours following surgery.

Urinating/Bowel Movements

After any surgery a patient may have trouble passing urine. This is uncommon and usually temporary. Occasionally a catheter needs to be inserted to help you pass urine. There may be some disturbance to your bowels in the week after surgery. Discuss this with your local doctor if this occurs.


It is usual to be discharged one – two days after pilonidal sinus surgery. It is very important to begin light activity shortly after surgery. This is to prevent pneumonia, clots in the legs and loss of general condition. You should avoid strenuous activity until the sinus is healed.

After discharge

Your Wound

  • If you have elective pilonidal surgery, you will have several stitches in the wound. These are usually removed at about 2 weeks.
  • Initially you will have a dressing covering the wound. This will be a pad and a piece of gauze impregnated with Vaseline. The pad can be changed the day after you go home.
  • Try and avoid getting the wound wet for at least 5days after surgery. After this, you may get the wound in the shower and let the water run over.
  • Do not rub the wound. Pat it dry with a towel.
  • After your bowels work do not rub the wound hard. Wash it in the shower if needed.
  • You can cover the wound with a simple pad to keep your underpants from soiling. (Ladies sanitary pads a cheap way to do this.)
  • If you have emergency pilonidal surgery, you will have an open wound that may be several centimeters deep. This will be packed everyday with a seaweed type dressing. This keeps the skin edges open and allows the wound to heal from the bottom out. A nurse will come to your house to do this dressing or alternately a family member can learn to do it.


  • Do not drive until you feel you could respond in an emergency.
  • You may walk normally and climb stairs.
  • You may start some light exercise when you feel comfortable. Strenuous sport should be avoided until the sinus is healed.
  • You may gently swim when the wound is healed.
  • You may resume sexual activity when you feel ready unless your doctor has told you otherwise.

How you may feel

  • It is quite common to feel quite tired for a few weeks after surgery.


  • Pilonidal sinuses need intensive follow-up. Expect to see your surgeon every week or two until the sinus has healed. This can take several months.

What are the symptoms of a pilonidal sinus?

Often, these sinuses cause no symptoms at all. They are sometimes found during a routine medical check. More often however, they are found when they become infected. This is very painful and occurs suddenly. The patient will usually present to the emergency department.