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Pilonidal Sinus M008

Last amended 
14 December 2021
Current RMA Instruments
Reasonable Hypothesis SOP27 of 2019 as amended
Balance of Probabilities SOP28 of 2019
Changes from previous Instruments

SOP Bulletin 227

ICD Coding
  • ICD-9-CM Code: 685
  • ICD-10-AM Code: L05
Brief description

A pilonidal sinus is a small hole, tunnel or pit of the skin. It is usually located in the fold between the buttocks but can develop elsewhere, including the hands and feet (interdigital spaces).  It generally contains embedded hair and can become infected, resulting in abscess formation with pain and discharge. It is most common in young adult males.

Confirming the diagnosis

The diagnosis is made on clinical grounds, from the history and findings on examination.  The diagnosis can be made by a treating GP.

The relevant medical specialist is a general surgeon.

Additional diagnoses covered by SOP

  • Pilonidal cyst
  • Pilonidal abscess
  • Sacrococcygeal fistula
Conditions not covered by SOP
  • Anal fistula#
  • Perianal abscess#
  • Hidradenitis suppurativa#

# Non-SOP condition

Clinical onset

Time of clinical onset will be based on reported symptoms, particularly pain.  The condition can be acute, recurrent or chronic.

Clinical worsening

 Treatment generally involves absecess drainage with debridement and/or surgical excision.  There is a low recurrence rate (< 10%) following surgery.