Description

A peritoneal space on each side of the falciform ligament, directly beneath the diaphragm and above the upper edge of the liver and the spleen. Subphrenic abscesses are infected focal fluid collections as a result of direct contamination due to surgery, trauma, local disease, or inflammatory processes.

Epidemiology

Incidence

• The specific incidence of subphrenic abscess is not well known; occurs after 1–2% of abdominal surgeries
• Most subphrenic abscesses are right-sided. Structures in the left upper quadrant (spleen and ligamentous attachments) protect the left subphrenic space. When a patient is supine, bacteria may traverse the paracolic gutters into the right subdiaphragmatic area.
• Risk of subphrenic abscess increases to 10–30% if:
  • Preoperative perforation of a hollow viscus
  • Significant fecal contamination of the peritoneal cavity
  • Bowel ischemia
  • Immunosuppression
  • Delayed diagnosis and treatment of peritonitis

Etiology and Pathophysiology

• Subphrenic abscesses most often form when bowel contents contaminate the peritoneal cavity.
• Subphrenic abscesses are generally polymicrobial (1):
  • Enteric gram-negative bacilli: Escherichia coli, Klebsiella spp., Enterobacter spp., Pseudomonas aeruginosa
  • Gram-positive cocci: Streptococcus spp., Enterococcus spp.
  • Obligate anaerobes: Bacteroides fragilis and other members of the Bacteroides group
• Microbiology is affected by exposure to the health care setting and prior antibiotic treatment, which can select for multidrug-resistant organisms (1).
• Health care–related isolates: Enterobacter spp., P. aeruginosa, and Enterococcus spp.; community isolates: E. coli (1)
• Local macrophage response to bacteria and foreign material leads to cytokine release, inflammatory cell and pathogen sequestration within an abscess. Fibrin and other adhesive molecules may also contribute to abscess formation within the mesentery, abdominal wall, omentum, or loops of bowel (1).

Risk Factors

• Abdominal surgery; inadvertent viscus perforation
• Anastomotic leak
• Peptic ulcer perforation
• Ruptured appendicitis
• Perforated diverticulitis
• Mesenteric ischemia with bowel infarction
• Penetrating abdominal trauma
• Infected pleural effusion or empyema (transdiaphragmatic seeding)

Commonly Associated Conditions

• Bacteremia
• Sepsis
• Multisystem organ failure
• Pleural effusion
• Fistula formation