What is the management approach for perianal swelling in a case of Tuberculosis (TB) psoas abscess?

Management of Perianal Swelling in TB Psoas Abscess

For perianal swelling in a patient with tuberculosis psoas abscess, surgical drainage of the perianal abscess is strongly recommended as the primary intervention, followed by appropriate anti-tuberculosis therapy. 1, 2

Diagnostic Approach

• Clinical diagnosis is usually sufficient for typical perianal abscesses, but imaging should be considered given the underlying TB psoas abscess 2
• CT scan is recommended due to its short acquisition time and widespread availability, with 77% sensitivity for detecting perirectal abscesses 1
• MRI may provide better soft tissue definition for complex cases involving TB 1
• Obtain samples during drainage for microbiological confirmation of TB involvement 1

Surgical Management

• Immediate surgical drainage is indicated for the perianal abscess 1, 2
• The incision should be kept as close as possible to the anal verge to minimize potential fistula length while ensuring adequate drainage 1
• Complete drainage is essential as inadequate drainage is associated with high recurrence rates (up to 44%) 1
• For small perianal abscesses, a trial of antibiotic therapy may be considered before surgery 1

Timing of Surgery

• Emergency drainage is indicated if the patient shows signs of sepsis, immunosuppression, diabetes mellitus, or diffuse cellulitis 1
• In the absence of these factors, surgical drainage should ideally be performed within 24 hours 1

Anti-tuberculosis Therapy

• Following drainage, a standard 6-month regimen for TB is recommended 1, 3
• Initial phase (2 months): isoniazid, rifampicin, pyrazinamide, and ethambutol 1, 3
• Continuation phase (4 months): isoniazid and rifampicin 1, 3
• Recommended dosages: isoniazid 5 mg/kg (up to 300 mg) daily, rifampicin 10 mg/kg (up to 600 mg) daily, pyrazinamide 35 mg/kg (up to 2.0 g) daily, and ethambutol 15 mg/kg daily 3

Management of Concomitant Fistulas

• If a fistula is identified during abscess drainage, place a non-cutting seton to prevent recurrent abscess formation 1, 2
• Definitive surgical repair of any fistula should be delayed until TB treatment has been completed and inflammation has resolved 1

Post-Operative Care

• Regular wound care and monitoring for healing 2
• Monitor for hepatotoxicity from anti-TB medications with liver function tests 1, 3
• If liver enzymes (AST/ALT) increase to five times normal or bilirubin increases, rifampicin, isoniazid, and pyrazinamide should be discontinued temporarily 1, 3

Special Considerations for TB Psoas Abscess

• The psoas abscess component typically requires separate management, which may include percutaneous drainage under CT guidance for abscesses >2 cm 4
• Small psoas abscesses (<2 cm) may respond to antibiotics alone 4
• Surgical intervention for the psoas component is rarely required unless percutaneous drainage fails 4, 5
• TB psoas abscesses often have bilateral involvement requiring comprehensive drainage 6

Follow-up

• Regular monitoring of response to anti-TB therapy 1
• Imaging follow-up is suggested in cases of recurrence or non-healing wounds 1
• Complete the full course of anti-TB therapy even after resolution of symptoms to prevent recurrence 1, 3

Pitfalls and Caveats

• Failure to obtain appropriate samples for TB culture may lead to missed diagnosis and inadequate treatment 1
• Inadequate drainage is the most common cause of recurrence 1
• Anti-TB medications can cause significant hepatotoxicity requiring careful monitoring 1, 3
• Concurrent proctitis may complicate management and should be assessed 1