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  • • Fever

    • Flank, abdominal, back, or thigh pain

    • Leukocytosis


  • • Retroperitoneal abscesses are less common than intraperitoneal abscesses

    • Primary abscesses are caused by hematogenous bacterial spread, most commonly S aureus

    • Primary abscesses are more common in underdeveloped countries

    • Secondary abscesses result from spread of infection from adjacent organs, principally from the intestine

    • Most common cause of retroperitoneal abscesses in developed countries is complicated Crohn disease

Symptoms and Signs

  • • Fever

    • Flank, abdominal, back, or thigh pain

    • Anorexia

    • Weight loss

    • Nausea and vomiting

    • Positive iliopsoas sign

    • Hip pain on extension

Laboratory Findings

  • • Leukocytosis

    • Evidence of inflammation: Elevated C-reactive protein and ESR levels

    • Common to have mild hematuria and pyuria when abscess adjacent to ureter or bladder

Imaging Findings

  • CT scan

    • -Most accurately delineates these lesions and can differentiate between retroperitoneal hematomas or tumors

      -Gas bubbles are diagnostic of a retroperitoneal abscess

      -Helpful in diagnosing the underlying etiology in patients with secondary retroperitoneal abscesses

    • Abscesses are confined to specific compartments whereas neoplasms frequently violate fascial barriers

  • • Etiology of retroperitoneal abscess:

    • -Crohn disease

      -Ruptured appendicitis


      -Perforated diverticulitis

      -Posterior penetrating duodenal ulcer

      -Regional enteritis

      -Retroperitoneal trauma



Rule Out

  • • Retroperitoneal hematoma

    • Retroperitoneal tumors

    • Intra-abdominal process with retroperitoneal extension

  • • CBC

    • Basic chemistries

    • Amylase and lipase

    • UA, culture, and sensitivity

    • Blood cultures

    • Most retroperitoneal abscesses are discovered radiographically during the work-up for another diagnostic consideration (ie, appendicitis)

    • Abdominal/pelvic CT scan with IV and PO contrast essential to characterize

When to Admit

  • • All patients should be admitted for definitive therapy and treatment monitoring

When to Refer

  • • Most patients should be managed by general surgeons

    • Subspecialty referral depends on underlying diagnosis (eg, Crohn disease)

  • • Percutaneous drainage may be attempted in well-defined uniloculated abscesses

    • Percutaneous catheter-based drainage has a lower success in retroperitoneal abscesses than with intra-abdominal abscesses


  • • Most patients will require open surgical debridement and drainage, ideally via an extraperitoneal flank approach


  • • Multiloculated abscesses

    • No clinical improvement within 2 days of percutaneous drainage

    • Involvement of psoas muscle or significant amount of necrotic debris present (catheters provide poor drainage for thick liquid or solid debris)

    • Large stellate-shaped abscesses that dissect along fascial planes


  • • Systemic empiric antibiotics that cover aerobic and anaerobic enteric organisms

    • Directed antibiotic therapy based on operative cultures

Treatment Monitoring

  • • Failure of fever or sepsis ...

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