Retroperitoneal Abscess



  • A collection of purulent fluid located in the space between the peritoneum and transversalis fascia lining the posterior abdominal cavity
  • Classified as primary if spread hematogenously or secondary if spread through infection of an adjacent organ
  • The retroperitoneum can be further subdivided into three compartments:
    • Anterior pararenal space
      • 2nd and 3rd segments of the duodenum, pancreas, bile duct, portal and splenic veins, appendix, ascending/descending colon, transverse mesocolon
    • Perirenal space
      • Kidneys, renal vessels, adrenal glands
    • Posterior pararenal space
      • Contains no major organs and is filled with fat, blood vessels, and lymphatics
      • Bounded by renal fascia and the muscles of the posterior abdominal wall



  • Most common in the 3rd to 6th decades (1)
  • Slight male predominance (1)

Rare condition in which perirenal abscesses are more common (2)

Etiology and Pathophysiology

  • Bowel perforation secondary to neoplastic disease, diverticulitis, pancreatitis, pancreatic cancer, retroperitoneal appendicitis, biliary tract disease, peptic ulcer disease, inflammatory bowel disease, peritonitis, colonoscopy following GI surgery, bowel infarction (1)
  • Genitourinary (GU) extravasation secondary to obstruction, nephrolithiasis, pyelonephritis, urinary tract infection, urologic surgery, pelvic surgery, ovarian cancer
  • Osteomyelitis of vertebral bodies or 12th rib, epidural abscess (1)
  • Less common causes are trauma, hematogenous or lymphatic seeding from a distant infection, or postoperative complication (1).
  • Infection seeds a confined space within the retroperitoneum.
  • Can be a monomorphic or polymorphic predominance of organisms
  • Typically consists of normal flora from adjacent organs (i.e., GI, GU, and female reproductive tract)
  • Hypoxia and lack of appropriate blood supply limit effective immune response.
  • Osmotic forces produce growth of abscess cavity.
  • Mycobacterium tuberculosis was previously a common pathogen but is less common today.
  • Most common pathogens
    • Staphylococcus aureus
    • Streptococcus sp.
    • Enterobacteriaceae
      • Citrobacter sp.
      • Escherichia coli
      • Klebsiella
      • Proteus sp.
      • Pseudomonas aeruginosa
      • Serratia
    • Anaerobes
      • Actinomyces
      • Peptostreptococcus
    • Bacteroides fragilis
      • Prevotella sp.
      • Clostridium sp.
    • Enterococcus sp.
    • Tuberculosis sp.
    • Fungus
      • Candida sp.

Pediatric Considerations
Consider necrotizing enterocolitis as an etiology in newborns.

Risk Factors

  • Appendicitis
  • Bowel perforation
  • Chronic urinary retention
  • Diabetes
  • Diverticulitis
  • Epidural infection
  • GU tract obstruction
  • Immunosuppression
  • Inflammatory bowel disease
  • Malignancy of the GU, GI, or female reproductive tract
  • Osteomyelitis of the spine or ribs
  • Pancreatitis
  • Pelvic inflammatory disease
  • Pregnancy
  • Pyelonephritis
  • Recent surgery of GU or GI
  • Renal biopsy
  • Tuberculosis (TB)

General Prevention

  • Treatment of the primary disease
  • Prevention of infection, such as perioperative antibiotic prophylaxis
  • Prompt treatment of symptomatic infection

Commonly Associated Conditions

  • Bowel perforation
  • Diabetes mellitus
  • Diverticulitis
  • Immunosuppression (HIV, glucocorticoid use)
  • Inflammatory bowel disease
  • Malignancy (GI or GU)
  • Nephrolithiasis
  • Osteomyelitis of the spine or ribs
  • Pelvic inflammatory disease
  • Renal insufficiency
  • Retroperitoneal hematoma
  • Surgery (GI or GU)
  • Urinary tract infections

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