Makindo Medical Notes

🦴 The diagnosis of an iliopsoas abscess may be suspected if a patient prefers lying supine with the knee flexed and hip mildly externally rotated – the position of greatest comfort.

📖 About

• ⚡ Early recognition and drainage reduce morbidity and mortality.
• 🫀 Involves the psoas and iliacus muscles (iliopsoas).
• 👨 More common in younger patients and males.

🧩 Anatomy

• 📍 Psoas originates T12–L5 → inserts at lesser trochanter of femur.
• 🧬 70% have only psoas major, 30% also have psoas minor (anterior).
• 💪 Fibres blend with iliacus → main hip flexor.
• ⚡ Innervated by L2–L4 (lumbar plexus).
• 🩸 Surrounded by venous plexus → prone to haematogenous spread.

🦠 Aetiology

• Spinal TB (esp. developing countries).
• IV drug use, diabetes, AIDS, renal failure, immunosuppression.
• Inflammatory bowel disease – Crohn’s is the most common secondary cause.

📌 Types

• Primary: Haematogenous spread (e.g. Staph aureus, TB).
• Secondary: Spread from Crohn’s, diverticulitis, appendicitis, or post-procedural infections.

🧫 Microbiology

• 🟡 Staphylococcus aureus → ~88% of primary cases.
• 🟢 Streptococcus → ~5%.
• 🔵 E. coli → ~3%.
• 🧬 Mycobacterium tuberculosis (common worldwide in TB endemic regions).
• Other: Proteus, Klebsiella, Bacteroides, Clostridium, MRSA, Salmonella, atypical mycobacteria.

🩺 Clinical Presentation

• Fever, weight loss, malaise.
• Flank, back, or abdominal pain radiating to groin.
• Limp or groin lump may be present.
• 🛏️ Classic posture: supine, hip flexed & externally rotated, knee flexed.
• Psoas signs:
  • Resisted hip flexion → pain.
  • Passive hip extension (patient on side) → pain.
  • May also be positive in appendicitis with psoas irritation but no abscess.

🔬 Investigations

• 🩸 FBC: ↑ WCC, ↑ ESR, ↑ CRP.
• 🧪 U&E: may show AKI; lactate if septic.
• 🖼️ CT abdomen/pelvis = gold standard for diagnosis.
• 💉 Fluid aspiration → culture & sensitivity.

⚠️ Complications

• 🩸 Compression of iliac vein → DVT.
• 🟡 Ureteric compression → hydronephrosis/renal impairment.
• 💥 Retroperitoneal haemorrhage.
• 🌡️ Sepsis, multi-organ failure.

💊 Management

• 🫁 ABC resuscitation → oxygen, IV fluids, analgesia, sepsis protocol.
• 💉 Broad-spectrum antibiotics (cover Staph/Strep/Gram negatives) → adjust after culture.
• 💉 Drainage: CT-guided percutaneous drainage (preferred) or surgical drainage if large/complex.
• ⚖️ Optimise comorbidities (e.g. diabetes control).

📌 UK Exam Pearls

• 👨 Young male with fever + back pain + limp → think psoas abscess.
• 🛏️ Classic posture (hip flexion + external rotation) is a diagnostic clue.
• 🧪 Staph aureus = most common cause (esp. primary abscess).
• 🌍 TB is an important cause worldwide (spinal spread).
• 📸 CT scan is the diagnostic gold standard.
• 💉 Early drainage + antibiotics = key to reducing mortality.
• 🇬🇧 In UK practice, consider Crohn’s disease when secondary psoas abscess is suspected.

🔗 References

• Iliopsoas Abscesses – Postgrad Med J Review