Pilonidal Sinus

Today, I went to colorectal clinic- only to discover that it was also a general surgery clinic when all the hernias came rolling in… There was also quite a bit of post-op colorectal cancer follow-up, an anal fissure and a teen with pilonidal sinuses.

This teen came in with pilonidal sinuses that she required treatment for, describing them as extremely painful, with a discharge of bloody pus, for which she had previously been prescribed antibiotics. After an examination, the doctor consented her for a pilonidal sinus excision +/- primary closure, and also advised that she have the hair of her lower back/natal cleft removed.

I’d sort of heard of these before and the way she was describing it I was pretty surprised when it came to having a look, because I could barely see these little monsters. I was expecting this massive pus-filled thing but instead I had to pretend that I could see something when the doctor pointed them out.

Pilonidal Sinus

Definition: an abnormal epithelium-lined tract filled with hair that opens to the skin surface, most commonly in the natal cleft (groove between buttocks), ~6cm above the anus

Aetiology/risk factors:

-ingrowing of hair, which penetrates the skin and excites a foreign body reaction, leading to sinus formation, with intermittent negative pressure drawing in more hair and perpetuating the cycle. May cause secondary tracks to open laterally +/- abscesses, with foul smelling discharge.

Image result for pilonidal sinus

Epidemiology: common, annual incidence 26 per 100,000

-Male: Female = ~ 10:1

-Mean age of presentation = 19yr (women), 21yr (men)

-Higher risk in obese Caucasians, Asian, Middle-Eastern, and Mediterranean

-Associated with hirsute (hairy) individuals


-painful natal cleft, especially if inflamed or infected

-discharge from sinuses

-swelling of sinuses


-midline openings or pits seen between buttocks, from which hair may protrude

-if associated infection or abscess: tender swelling that may be fluctuant or discharge pus or bloodstained fluid on compression


Diagnosis can be made on clinical examination.


If acute pilonidal abscess has formed:

-incision and drainage of abscess for evacuation of pus and hair

-cavity irrigated and packed (with dressing), and dressings changed regularly until there is secondary closure

Chronic pilonidal sinus:

-Excision of the sinus tract +/- primary closure (otherwise, leaving wound open and allowing healing by secondary intention = slower healing but less recurrence)

-Consider pre-op antibiotics

-Offer hygiene and hair removal advice for prevention of recurrence

Complications: pain, infection, abscess, recurrence

Prognosis: good with appropriate management. Complicated disease can be troublesome and cause recurrent infection. Usually resolves by age of 40.

References: Cheese & Onion, Rapid Surgery


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