- An abscess is collection of pus within soft tissues
- Occurs when hosts response to infection is inadequate
- Predisposing factors include foreign bodies, haematoma formation and poor blood supply
Pathology
- An abscess contains bacteria, acute inflammatory cells, protein exudate and necrotic tissue
- It is surrounded by granulation tissue (the 'pyogenic membrane')
- The organisms usually involved are:
- In superficial abscesses - Staph. aureus, Strep. pyogenes
- In deep abscesses - Gram negative species (e.g. E. coli) and anaerobes (e.g. Bacteroides)
Clinical features
- Superficial abscesses include infected sebaceous cysts, breast and pilonidal abscesses
- Show cardinal features of inflammation - calor, rubor, dolor, tumor
- Heat
- Redness
- Pain
- Swelling
- After a few days superficial abscess usually 'point' and are fluctuant
- Deep abscesses include diverticular, subphrenic and anastomotic leaks
- Patients shows signs of inflammation - swinging pyrexia, tachycardia, tachypnoea
- Physical signs are otherwise difficult to demonstrate
- Site of abscess may not be clinically apparent
- Radiological imaging often required to make the diagnosis
Treatment
- All abscesses require adequate drainage
- Should be performed under general anaesthesia
- Antibiotics have little to offer as tissue penetration is usually poor
- Prolonged antibiotic treatment can result in a chronic inflammatory mass (an 'antibioma')
- Superficial abscesses are usually suitable for open drainage
- For deep abscesses closed drainage may be attempted
Open technique
- Superficial abscesses can usually be drained through a cruciate incision
- Position of incision may allow depended drainage
- Pus should be sent for microbiology
- Loculi should be broken down and necrotic tissue excised
- A dressing should be inserted into the wound
- Packing is not required - it is painful
Closed techniques
- Deep abscess can be treated by ultrasound or CT guided aspiration
- Success can not always be guaranteed
- Multiloculated abscesses may not drain adequately
- Percutaneous access my be difficult because of the position of adjacent organs
Bibliography
Abraham N, Doudle M, Carson P. Open versus closed treatment of abscesses. a controlled
clinical trial. Aust NZ J Surg 1997; 67: 173-176. |