Subphrenic Abscess – Causes, Symptoms, Diagnosis, Treatment and Ongoing care


  • Subphrenic abscess is a location-specific intraabdominal abscess, also referred to as a complicated abdominal infection.
  • Synonyms: Sub- or infradiaphragmatic abscess


A localized, fibrous, encapsulated collection of pus directly under the diaphragm.



The incidence of subphrenic abscess is not well known. Overall, intra-abdominal abscess formation after abdominal surgery occurs in 1–2% of cases; however, the risk increases to 10–30% in cases with preoperative perforation of a hollow viscus, significant fecal contamination of the peritoneal cavity, bowel ischemia, immunosuppression, or delayed diagnosis and treatment of peritonitis.

Risk Factors

  • Abdominal surgery, especially with inadvertent viscus perforation
  • Anastomotic leak
  • Peptic ulcer perforation
  • Ruptured appendicitis
  • Perforated diverticulitis
  • Mesenteric ischemia with bowel infarction
  • Abdominal trauma, especially penetrating
  • Foreign body ingestion with viscus perforation


  • Subphrenic abscess typically forms when contents of the gastrointestinal tract are released into the sterile peritoneal cavity. When a patient is supine, bacteria may traverse the paracolic gutters into the right subdiaphragmatic area leading to abscess formation in a location proximate or remote to its origin. Structures in the left upper quadrant (spleen, ligaments) tend to protect the left subphrenic space from remote soiling, and infections in this region are uncommon, usually arising from gastric perforation or from transdiaphragmatic spread from the left chest.
  • Pattern recognition receptors on local macrophages are stimulated by the presence of bacteria and foreign material, leading to the release of cytokines, promoting an influx of polymorphonuclear leukocytes, monocytes, and ultimately sequestration of the pathogens within an abscess. Microorganisms may also be sequestered on a macroscopic scale involving fibrin and other adhesive molecules adhering to mesentery, the abdominal wall, omentum, and loops of bowel (1).


  • Subphrenic abscess typically is a polymicrobial infection due to gastrointestinal tract flora, consisting of aerobic and anaerobic bacteria. The most prevalent microorganisms include aerobic enteric gram-negative bacilli and gram-positive cocci, and anaerobes. Below is a table of commonly isolated pathogens (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
  • The microbiology of the infection is affected by exposure to the health care setting and prior antibiotic treatment, which can select for multidrug-resistant organisms (1). Consequently, isolates in health care–associated cases are different than in community-acquired cases, with Enterobacter spp., Pseudomonas aeruginosa, and Enterococcus spp. isolated more frequently than E. coli (1).

Commonly Associated Conditions

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


Early diagnosis is critical to reducing morbidity and mortality.


  • Recent history of abdominal surgery, usually from weeks to months earlier, occasionally more remotely (2)
  • Constitutional symptoms: Fever, chills, diaphoresis, malaise
  • Pain symptoms: Chest, shoulder (referred pain to the scapular area), and/or abdominal pain
    • Pain in respective upper quadrant, but may be pleuritic
  • Respiratory symptoms: Nonproductive cough, dyspnea
  • GI symptoms: Nausea, hiccups, vomiting, adynamic ileus

Physical Exam

  • Fever, tachycardia, hypotension
  • Rales at lung base
  • Dullness to percussion at lung base
  • Decreased breath sounds at lung base
  • Subcostal, costal, and/or abdominal tenderness
  • Pseudo-organomegaly, secondary to palpable mass lesion

Diagnostic Tests & Interpretation


  • Complete blood count: Leukocytosis, often with left shift; anemia
  • Blood cultures: Positive in no more than 50% of cases, but may guide selection and duration of antibiotic therapy (B-III) (3).
  • Cultures of aspirate: Fluid should be sent to laboratory for Gram stain and culture.

Follow-Up & Special Considerations

  • After broad-spectrum antibiotic therapy has been initiated and drainage established, the patient can be expected to defervesce within 24–48 hours. If the patient fails to improve clinically, follow-up CT scan is indicated.
  • Monitor vital signs and metabolic function to detect septic shock.
    • Basic metabolic panel
    • Liver chemistries


  • Abdominal radiograph maybe done initially. Findings may include elevation of the hemidiaphragm, subphrenic air-fluid level.
  • CT scan of the abdomen, pelvis, and lower chest with contrast is the most appropriate imaging study in a patient who may have an intra-abdominal abscess (4).

Differential Diagnosis

  • Liver abscess
  • Subhepatic abscess
  • Lesser sac abscess
  • Splenic abscess
  • Empyema


  • Consists of three modalities:
    • Source control (percutaneous or surgical drainage of the abscess)
    • Broad-spectrum antibiotics
    • Aggressive fluid resuscitation.


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  • Broad-spectrum antibiotics:
    • Begin antimicrobial therapy as soon as subphrenic abscess is considered likely or confirmed and immediately in patients with septic shock (A-III) (3).
    • Adequate antimicrobial drug dosing should be maintained (A-I) (3).
    • More than 1 agent is generally required to provide adequate coverage for suspected organisms (5).
  • Empiric treatment for intra-abdominal infection of mild to moderate severity that is not related to health care (without severe physiologic derangement, advanced age, or immunocompromised state) (A-I) (3):
Single agent Ertapenem, piperacillin-tazobactam, or tigecycline
Combination therapy 5 Ceftriaxone, cefotaxime, ciprofloxacin, or levofloxacin, each in combination with metronidazole
  • Empiric treatment for complicated, high-risk intra-abdominal infection not related to health care or in patients with severe physiologic derangement, advanced age, or immunocompromised state (A-1) (3):
Single agent Imipenem-cilastatin, meropenem, doripenem, or piperacillin-tazobactam
Combination therapy 5 Cefepime, ceftazidime, ciprofloxacin, or levofloxacin, each in combination with metronidazole
  • As described above, the microbiology in patients with prior hospital exposure may be altered and warrant coverage for multidrug-resistant organisms (1). Empiric antibiotic therapy for health care–associated intra-abdominal infection should be guided by local microbiologic results (A-II) (3) and later tailored based on culture results (B-III) (3).
  • Duration of antimicrobial therapy of an established complicated intra-abdominal infection should be 4–7 days, after adequate drainage and patient has defervesced, longer if it is difficult to obtain adequate source control (B-III) (3).

Additional Treatment

General Measures

Intravenous fluid hydration

  • Patients with signs of intravascular volume depletion should have rapid restoration of fluid status (A-II) (3).
  • Administer intravenous fluids to euvolemic patients without evidence of volume depletion when diagnosis of intra-abdominal abscess is first suspected. (B-III) (3)

Surgery/Other Procedures

  • Percutaneous drainage is the treatment of choice for patients without an acute abdomen (B-II) (3).
  • General surgery consult should be obtained in virtually all cases of suspected intra-abdominal abscess and may be especially valuable in cases of recurrence or multiple subphrenic abscesses deemed not amendable to percutaneous drainage.

Ongoing Care


  • Morbidity and mortality vary depending on the comorbid conditions, severity of the patient’s status, and etiology.
  • Percutaneous abscess drainage is curative in >85% of cases (6).
  • Recurrence rate of abscess is 1–10% (6).


  • Bacteremia
  • Sepsis
  • Rupture of abscess
  • Abscess recurrence
  • Pleural effusion
  • Risk of morbidity and mortality increases with multiple surgeries, age >50 years, and recurrent or persistent abscesses.


1. Mazuski JE, Solomkin JS, et al. Intra-abdominal infections. Surg. Clin. North Am. 2009;89:421–37, ix

2. Tomita H, Osada S, Miya K, et al. Delayed recurrence of postoperative intra-abdominal abscess: an unusual case and review of the literature. Surg Infect (Larchmt). 2006;7:551–4.

3. Solomkin JS, Mazuski JE, Bradley JS, et al. Diagnosis and management of complicated intra-abdominal infection in adults and children: guidelines by the Surgical Infection Society and the Infectious Diseases Society of America. Clin Infect Dis. 2010;50:133–64.

4. Rosen MP, Bree RL, Foley WD, et al. Acute abdominal pain and fever or suspected abdominal abscess. [online publication]. Reston (VA): American College of Radiology (ACR); 2006:7.

5. Wong PF, Gilliam AD, Kumar S, et al. Antibiotic regimens for secondary peritonitis of gastrointestinal origin in adults. Cochrane Database Syst Rev.2005;CD004539.

6. Akinci D, Akhan O, Ozmen MN, et al. Percutaneous drainage of 300 intraperitoneal abscesses with long-term follow-up. Cardiovasc Intervent Radiol. 744–50.



567.22 Peritoneal abscess


52478002 subdiaphragmatic abscess (disorder)

Clinical Pearls

  • Subphrenic abscess occurs after contamination of the sterile peritoneal cavity with gastrointestinal tract bacteria.
  • Proper management involves determining the cause of the infection, abscess drainage, broad-spectrum antibiotics, and intravenous fluids.

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