Subphrenic Abscess  

Subphrenic Abscess  

• A localized accumulation of infected fluid, often encapsulated, located under the diaphragm and may also involve the liver and spleen

Synonyms

• Subdiaphragmatic abscess
• Infradiaphragmatic abscess

Epidemiology & Demographics

Incidence

How common is Subphrenic Abscess?

• Not well known but intraabdominal abscess occurs in 1% to 2% of all cases of abdominal surgery.
• It increases to 10% to 30% in cases with preoperative perforation of a hollow viscus, spillage of fecal material into peritoneum, or intestinal ischemia.

What are the Risk Factors?

• Abdominal surgery, especially with accidental viscus perforation
• Peptic ulcer perforation
• Appendiceal perforation
• Diverticulitis with perforation
• Mesenteric ischemia with bowel infarction
• Abdominal trauma especially penetrating trauma
• Foreign body ingestion with subsequent viscus perforation

What are the Physical Findings & Clinical Presentation?

• •Constitutional symptoms include:
  • 1.Fever, malaise, or chills
  • 2.Cough, increased respiratory rate with shallow or grunting respiration
  • 3.Shoulder-tip pain on affected side (referred pain)
• •Physical findings can include:
  • 1.Dullness to percussion on affected side
  • 2.Diminished or absent breath sounds on affected side
  • 3.Tenderness over the eighth to eleventh ribs

What causes Subphrenic Abscess?

• Infection is usually polymicrobial: Aerobic gram-negative rods, most commonly Escherichia coli, Klebsiella species, Enterobacter species, and Pseudomonas aeruginosa, and gram-positive cocci: Streptococcus viridans, enterococci, and Staphylococcus aureus, and anaerobes (found in 60% to 70% of cases) such as Bacteroides fragilis and Clostridia species.

Differential Diagnosis

• Liver abscess
• Subhepatic abscess
• Lesser sac abscess
• Empyema of the lung
• Diaphragmatic hernia

Workup

• Should be started in patients with recent abdominal surgery (weeks to months) with the constitutional symptoms and physical findings mentioned above

What are the Laboratory Tests done to diagnose Subphrenic Abscess?

• Complete blood count with differential may show an elevated white blood count with left shift.
• Blood cultures may be positive in up to 50% of the cases.
• Gram stain and culture, aerobically and anaerobically, of any aspiration procedure.

Imaging Studies

• Plain x-ray films can suggest the location of the abscess in about 50% of the cases and can demonstrate elevation of the hemidiaphragm and/or subphrenic air-fluid level.
• Ultrasonography and CT are more sensitive.
• Other options include leukocyte tagged with gallium 67 and indium 111 scans and MRI.

How is Subphrenic Abscess treated?

Includes source control with either percutaneous drainage or surgery and intravenous antibiotics:

Percutaneous drainage via interventional radiology:

1.Percutaneous drainage ¹ with catheter placement remains the preferred treatment despite the fact that the subphrenic location can be problematic for imaging-guided percutaneous drainage.

2.Approaches include subcostal approach or intercostal approach. The intercostal approach is associated with a higher risk for pleural complications, but these tend to be minor. ²

3.Radiographic modalities used include ultrasonography, CT, and fluoroscopy.

4.Complications of drainage procedures can include pleural effusion, pneumothorax, or empyema.

•Surgery: May be required in recurrence of abscess or due to multiple abscesses not amenable to percutaneous drainage procedure

•Antibiotics: Broad-spectrum antibiotics should be used to cover gram-negative rods, gram-positive bacteria, and anaerobes until cultures are resulted and should be continued at least 4 to 7 days after adequate drainage procedure. Examples include:

1.Piperacillin/tazobactam 3.375 g IV q6h or 4.5 g IV q8h

2.Meropenem 1 g IV q8h or imipenem 0.5 to 1 g IV q6h

3.Ciprofloxacin IV 400 mg IV q12h plus IV metronidazole 500 mg IV q8h for penicillin allergic patients

Referral

•Interventional radiology

•General surgery

•Infectious diseases

Pearls & Considerations

• Success of percutaneous drainage procedures is greater than 85%, and recurrence rates are about 1% to 10%.