What is the management approach for a patient with a right psoas and paraspinal abscess?

Management of Right Psoas and Paraspinal Abscess

The optimal management combines prompt drainage (percutaneous CT-guided for most cases, surgical for complex or failed percutaneous attempts) with prolonged antibiotic therapy, while addressing any underlying spinal pathology that may be the primary source of infection. 1, 2

Initial Diagnostic Evaluation

Imaging is essential for diagnosis and treatment planning:

• CT scanning is the first-line imaging modality for identifying and characterizing psoas and paraspinal abscesses 3, 4
• MRI provides superior tissue characterization and is particularly valuable for evaluating spinal involvement as the primary infectious source 1, 4
• Ultrasound has superior sensitivity (81-88%) and specificity (83-96%) for identifying septations and loculations compared to CT 3

Critical clinical features to assess:

• Back pain (present in 76.8% of cases) and fever (53.6%) are the most common presenting symptoms 5
• History of recent spinal surgery, invasive spinal procedures, or intravenous drug use 1, 2
• Signs of spinal instability, neurological compromise, or epidural extension requiring urgent surgical consultation 6

Treatment Algorithm

Step 1: Determine Drainage Strategy Based on Abscess Characteristics

For abscesses ≤2 cm without loculations:

• Antibiotics alone may be sufficient (34% of cases successfully managed this way) 2
• Close monitoring with repeat imaging is essential 3

For abscesses >2 cm or symptomatic collections:

• CT-guided percutaneous drainage (PCD) is the preferred initial approach with 90% overall success rate 2
• PCD is particularly effective for uniloculated abscesses in patients with high operative risk 1
• Median abscess size successfully treated with PCD is 6 cm 2

Predictors of PCD failure requiring surgical intervention:

• Multiloculation with thick septations 3
• High viscosity contents or necrotic debris 3
• Abscesses >5 cm with complex anatomy 3
• Failed initial PCD (recurrence rate 1.8-10% depending on technique) 5, 2

Step 2: Surgical Approach Selection (When PCD Fails or Contraindicated)

Retroperitoneoscopic drainage is the preferred minimally invasive surgical option:

• Safe and effective with no major (Clavien-Dindo >3) complications reported 5
• Recurrence rate of only 1.8% at 21-month follow-up 5
• Allows direct visualization and complete evacuation of loculated collections 5

Open surgical drainage indications:

• Failed retroperitoneoscopic or percutaneous approaches 1, 7
• Presence of spinal instability or epidural abscess requiring concurrent spinal surgery 6, 1
• Multiple recurrences after less invasive approaches 2

Step 3: Address Primary Spinal Source

The spine is frequently the primary source of infection and must be treated concurrently:

• Obtain surgical spine consultation early, particularly if imaging shows spondylodiscitis, vertebral destruction, or epidural involvement 6, 1
• Aggressive surgical debridement of infected spinal tissue is essential as antifungal/antibiotic therapy alone is often insufficient 6
• Multiple operations may be necessary to eradicate bone and soft-tissue infection and restore spinal stability 1

Specific spinal surgical considerations:

• Anterior approach for disc space or vertebral body infections with less morbidity 6
• Posterior approach for epidural abscess decompression, though associated with higher pain and wound complications 6
• Immobilization with external bracing for isolated discitis without instability 6

Antibiotic Therapy

Broad-spectrum IV antibiotics must accompany all drainage procedures:

• Cover Gram-positive (including Staphylococcus aureus), Gram-negative (including Klebsiella pneumoniae, Enterobacter), and anaerobic bacteria 3, 5
• Obtain cultures during drainage to guide targeted therapy 3
• Continue antibiotics for 2-3 weeks after normalization of inflammatory markers (ESR, CRP) 1

Special pathogen considerations:

• Mycobacterium tuberculosis is the causative agent in 92.8% of cases in some series, requiring prolonged anti-tuberculous therapy 5
• Adjust antibiotic duration based on culture results and clinical response 1

Adjunctive Measures for Complex Collections

For inadequate drainage or persistent loculations:

• Upsize drainage catheter to larger bore 3
• Consider intracavitary thrombolytic therapy to break up septations 3
• Place multiple drainage catheters for complex multiloculated collections 3
• Ultrasound guidance during drainage helps identify and break up septations 3

Critical Pitfalls to Avoid

Inadequate drainage is the primary cause of treatment failure:

• Incomplete evacuation leads to high recurrence rates (up to 10%) 3, 1
• Underestimating abscess viscosity results in inappropriate catheter selection 3

Delayed diagnosis of spinal source:

• Always evaluate the spine with MRI when psoas abscess is diagnosed, as spinal pathology is increasingly common 1, 4
• Missing concurrent spondylodiscitis or epidural extension leads to treatment failure 6, 1

Premature discontinuation of antibiotics:

• Continue therapy for full 2-3 weeks after inflammatory markers normalize, not just until clinical improvement 1

Monitoring and Follow-up

Imaging surveillance is essential:

• Weekly MRI for patients managed conservatively with immobilization to detect disease progression 6
• Repeat CT or MRI if clinical improvement plateaus or symptoms recur 1, 7
• Monitor for spinal instability development requiring delayed surgical stabilization 6, 1