Retroperitoneal Abscess

• • Fever

  • Flank, abdominal, back, or thigh pain

  • Leukocytosis

Epidemiology

• • 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

    -Pancreatitis

    -Perforated diverticulitis

    -Posterior penetrating duodenal ulcer

    -Regional enteritis

    -Retroperitoneal trauma

    -Pyelonephritis

    -Osteomyelitis

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

Surgery

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

Indications

• • 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

Medications

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

  • Directed antibiotic therapy based on operative cultures

Treatment Monitoring

• • Failure of fever or sepsis ...