Perianal Abscess on Call

Jim Hill, Consultant Colorectal Surgeon

Powerpoint File

Why it's fun to drain abscesses? Because you can't infect pus - Aphorisms & Quotations for the Surgeon

1023 perianal abscesses

Ramanujam PS, Prasad ML, Abcarian H et al Dis Colon Rectum 1984;27:593-7

Perianal 43%

Ischiorectal 23%

Intersphincteric 22%

Supralevator 8%

Fistula 35%

Suprasphincteric 3.2%

Recurrence

1.7 % abscess drainage only

3.8% primary fistula with drainage

BSTs need to be taught the basic steps of abscess drainage and when to ask for assistance. They will not have read anything about general surgical emergencies nor have any experience of perianal abscess drainage.They need to know that the anal canal is inspected for pus emerging from an internal opening, rigid sigmoidoscopy is mandatory to look for proctitis and biopsy essential to exclude TB, lymphoma, mucinous adenocarcinoma etc. They need to recognise circumstances where Fournier's gangrene is more likely; elderly, immunocompromised, alcoholic, IVDAs, patients with co-existing cardiorespiratory and renal disease, diabetes and which abscesses are more likely to be complex; recurrent, bilateral, Crohn's disease, obese. Recurrent anorectal abscesses are associated with the presence of a fistula in nearly 80%. When any of these situations occur the BSTs must ensure that they get assistance and advice in theatre.

There is a reported incidence of early re-operation for peri rectal abscess as high as 10%. Surgical errors were the leading cause of early failures. The findings on re-operation are incomplete drainage, missed loculations, missed abscesses and bleeding. Horseshoe abscesses were associated with a 50% failure rate. When a fistula is identified fistulotomy results in fewer recurrences. Incision, curettage and primary suture under antibiotic cover is associated with recurrence rates of 15-24%. Healing time is about 10 days versus 35 days on standard treatment.

Simple incision and drainage of pilonidal abscess is associated with a permanent healing rate of only 37%. Median healing time for pilonidal sinus wounds is nearly 60 days. Left to their own devices BSTs will typically perform incision and drainage.

Patients with perianal sepsis come low down the order of priorities for the emergency list. Ways of improving management for simple cases include; following assessment in A&E and analgesia admitting the patient onto the day case unit the following morning, bookable cases on the emergency list, ensuring appropriate priority for serious cases and specialist wound dressing clinics. In the USA the initial drainage is frequently performed under local anaesthetic in the surgeon's office.

There have been two extensive reviews (Health Technology Assessment and Cochrane Systematic) of the clinical effectiveness and cost-effectiveness of debriding agents in treating surgical wound healing by secondary intention. Not a single large quality randomised clinical trial was found. Overall the reviews concluded that modern dressings hydrocolloid, alginate and foam (silicone and polyurethane) were associated with less pain, greater satisfaction and were cost effective compared to traditional gauze dressings.

Perianal infections are common complications in immuno-compromised patients; (leukaemia 8%, bone marrow transplant 2.5%). When there is evidence of fluctuance and a normal neutrophil count surgical drainage is safe and effective. When there is cellulitis without fluctuance and neutropaenia mortality rates are high, treatment with broad spectrum antibiotics is appropriate, but if the infection is resistant to medical treatment there should be no hesitation in proceeding to surgical treatment.

In HIV +ve patients low CD 4+ lymphocyte counts are associated with more severe septic complications, poor wound healing and metastatic abscess. Idiopathic ulcers of the anal canal in HIV +ve patients are frequently associated with an intersphincteric abscess. The prevalence and distribution of HIV related anorectal pathology has not been altered by the introduction of antiretroviral therapy.