Health Dictionary Find a Doctor

Peritonitis

For patient information click here

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Seyedmahdi Pahlavani, M.D. [2]
Synonyms and keywords:Peritoneal inflammation

Overview

Overview

Peritonitis defined as inflammation of peritoneum (serosal membrane lining the abdominal cavity and abdominal viscera) and is associated with high mortality rate secondary to bacteremia and sepsis syndrome. Most common cause of peritonitis in approximately 80% adults is perforation of the gastrointestinal or biliary tract. Other less common causes include liver cirrhosis, and peritoneal dialysis associated peritonitis. Peritonitis can also result from injury, contamination with microorganisms, chemicals or both. It may be localized or generalized, and can have an acute course in infection secondary to rupture of a hollow viscus or follows a chronic course as seen in tuberculous peritonitis. Patients present with severe abdominal pain associated with fever, chills, nausea and vomiting. Peritonitis must be differentiated from other diseases affecting the peritoneum such as peritoneal abscess, peritoneal mesothelioma and peritoneal carcinomatosis which presents with ascites and abdominal pain. Peritonitis is a emergency medical condition requiring prompt medical attention and treatment.

Causes

Causes


Common causes Less common causes Comment
Spontaneous bacterial peritonitis To see a complete list of causes, click here.
Secondary peritonitis To see a complete list of causes, click here.


Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Venkata Sivakrishna Kumar Pulivarthi M.B.B.S [2] Shivani Chaparala M.B.B.S [3]

Overview

The most common cause of peritonitis is perforation of a hollow viscus such as perforation of the distal esophagus (Boerhaave syndrome), of the stomach (peptic ulcer, gastric carcinoma), of the duodenum (peptic ulcer), of the remaining intestine (e.g. appendicitis, diverticulitis, Meckel’s diverticulum, IBD, intestinal infarction, intestinal strangulation, colorectal carcinoma, meconium peritonitis), or of the gallbladder (cholecystitis). Other causes of infected peritonitis include spontaneous bacterial peritonitis and disruption of the peritoneum, such as in cases of trauma, surgical wounds, continuous peritoneal dialysis, and intra-peritoneal chemotherapy. Causes of non-infected peritonitis include endometriosis, blunt abdominal trauma, gastric carcinoma, peptic ulcer, pelvic trauma, and pancreatitis.

Causes

Causes of peritonitis can be divided into infected and non-infected, which are as follows:

Causes of Infected Peritonitis

Perforation of a hollow viscus organ Disruption of the peritoneum Spontaneous bacterial peritonitis (SBP) Systemic infections
Perforation of a hollow viscus (most common cause of peritonitis)

Other possible causes for perforation

Most common organisms -mixed bacteria

Most common organisms

Peritonitis occurring in the absence of an obvious source of contamination. It occurs either in children, or in patients with ascites.

e.g. Tuberculosis

Causes of Non-Infected Peritonitis

Leakage of sterile body fluids into the peritoneum Sterile abdominal surgery Rarer non-infectious causes
Sterile body fluids such as

These body fluids are sterile at first, they frequently become infected once they leak out of their organ, leading to infectious peritonitis within 24-48h.

Due to sterile foreign body inadvertently left in the abdomen after surgery (e.g. gauze, sponge)

Causes by Organ System

Cardiovascular No underlying causes
Chemical/Poisoning No underlying causes
Dental No underlying causes
Dermatologic No underlying causes
Drug Side Effect No underlying causes
Ear Nose Throat No underlying causes
Endocrine No underlying causes
Environmental No underlying causes
Gastroenterologic Appendicitis, Ascites, Boerhaave syndrome, Cholecystitis, Cholelithiasis, Chronic liver disease, Diverticulitis, Gall bladder rupture, Gastrointestinal perforation, IBD, Intestinal strangulation, Mallory-Weiss syndrome, Meckel diverticulitis, Meconium peritonitis, Neonatal necrotizing enterocolitis, Pancreatitis, Peptic ulcer, Perihepatitis, Recurrent hereditary polyserositis, Toxic megacolon, Typhlitis
Genetic No underlying causes
Hematologic No underlying causes
Iatrogenic Continuous ambulatory peritoneal dialysis, Intra-peritoneal chemotherapy, Surgical wounds
Infectious Disease Bacteroides fragilis, E. coli, Enterobacteriaceae, Escherichia coli, Fitz-Hugh Curtis syndrome, Klebsiella pneumoniae, Pseudomonas, Staphylococcus, Streptococcus pneumoniae, Streptococcus pyogenes, Miliary tuberculosis
Musculoskeletal/Orthopedic No underlying causes
Neurologic No underlying causes
Nutritional/Metabolic No underlying causes
Obstetric/Gynecologic Endometriosis, Fitz-Hugh Curtis syndrome, Pelvic inflammatory disease
Oncologic Colorectal carcinoma
Ophthalmologic No underlying causes
Overdose/Toxicity No underlying causes
Psychiatric No underlying causes
Pulmonary No underlying causes
Renal/Electrolyte Nephritic syndrome
Rheumatology/Immunology/Allergy Systemic lupus erythematosus
Sexual No underlying causes
Trauma Trauma
Urologic No underlying causes
Miscellaneous Ruptured dermoid cyst, Spontaneous bacterial peritonitis

Causes in Alphabetical Order

References


Template:WikiDoc Sources

Classification

Classification

Peritonitis is classified based on the cause of the inflammatory process and the character of microbial contamination as follows:[1][2][3]

 
 
 
 
 
 
 
 
Peritonitis
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Primary peritonitis
 
 
 
 
Secondary peritonitis
 
 
 
 
Tertiary peritonitis
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
❑ Spontaneous peritonitis
❑ Peritonitis in patients with CAPD
❑ Tuberculous peritonitis
 
 
 
 
 
 
 
 
 
 
 
 
❑ Peritonitis without evidence for pathogens
❑ Peritonitis with fungi
❑ Peritonitis with low-grade pathogenic bacteria
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Acute perforation peritonitis
❑ Gastrointestinal perforation
❑ Intestinal ischemia
❑ Pelviperitonitis and other forms
 
 
Postoperative peritonitis
❑ Anastomotic leak
❑ Accidental perforation and devascularization
 
 
Post-traumatic peritonitis
❑ After blunt abdominal trauma
❑ After penetrating abdominal trauma
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 


Differential diagnosis

Differential diagnosis

Classification of acute abdomen based on etiology Presentation Symptoms Signs Diagnosis Comments
Fever Abdominal Pain Jaundice Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging
Common causes of Peritonitis Primary Peritonitis Spontaneous bacterial peritonitis + Diffuse Hypoactive
  • Ascitic fluid PMN>250 cells/mm³
  • Culture: Positive for single organism
Ultrasound for evaluation of liver cirrhosis
Secondary Peritonitis Perforated gastric and duodenal ulcer + Diffuse + + N
    • Glucose < 50mg/dl
    • Total protein > 1g/dl
Air under diaphragm in upright CXR Upper GI endoscopy for diagnosis
Acute cholangitis + RUQ + N Abnormal LFT Ultrasound shows biliary dilatation Biliary drainage (ERCP) + IV antibiotics
Acute cholecystitis + RUQ + Hypoactive Ultrasound shows gallstone and evidence of inflammation Murphy’s sign
Acute pancreatitis + Epigastric +/- N Increased amylase / lipase Ultrasound shows evidence of inflammation Pain radiation to back
Acute appendicitis + RLQ + + Hypoactive Leukocytosis Ultrasound shows evidence of inflammation Nausea & vomiting, decreased appetite
Acute diverticulitis + LLQ +/- + Hypoactive Leukocytosis CT scan and ultrasound shows evidence of inflammation
Acute salpingitis + LLQ/ RLQ +/- +/- N Leukocytosis Pelvic ultrasound Vaginal discharge
Hollow Viscous Obstruction Small intestine obstruction Diffuse + +/- Hyperactive then absent Leukocytosis Abdominal X ray Nausea & vomiting associated with constipation, abdominal distention
Volvulus Diffuse + Hypoactive Leukocytosis CT scan and abdominal X ray Nausea & vomiting associated with constipation, abdominal distention
Biliary colic RUQ + N Increased bilirubin and alkaline phosphatase Ultrasound Nausea & vomiting
Renal colic Flank pain N Hematuria CT scan and ultrasound Colicky abdominal pain associated with nausea & vomiting
Vascular Disorders Ischemic causes Mesenteric ischemia +/- Periumbilical Hyperactive Leukocytosis and lactic acidosis CT scan Nausea & vomiting, normal physical examination
Acute ischemic colitis +/- Diffuse + + Hyperactive then absent Leukocytosis CT scan Nausea & vomiting
Hemorrhagic causes Ruptured abdominal aortic aneurysm Diffuse N Normal CT scan Unstable hemodynamics
Intra-abdominal or retroperitoneal hemorrhage Diffuse N Anemia CT scan History of trauma
Gynaecological Causes Ovarian Cyst Complications Torsion of the cyst RLQ / LLQ +/- +/- N Increased ESR and CRP Ultrasound Sudden onset sever pain with nausea and vomiting
Cyst rupture RLQ / LLQ +/- +/- N Increased ESR and CRP Ultrasound Sudden onset sever pain with nausea and vomiting
Pregnancy Ruptured ectopic pregnancy RLQ / LLQ N Positive pregnancy test Ultrasound History of missed period and vaginal bleeding
Differentiating the different causes of peritonitis
Disease Prominent clinical findings Lab tests Tratment
Primary peritonitis Spontaneous bacterial peritonitis
Tuberculous peritonitis
Continuous Ambulatory Peritoneal Dialysis (CAPD peritonitis)
Secondary peritonitis Acute bacterial secondary peritonitis
Biliary peritonitis
Tertiary peritonitis
Familial Mediterranean fever (periodic peritonitis, familial paroxysmal polyserositis)
  • Colchicine prevents but does not treat acute attacks.
Granulomatous peritonitis
  • Diagnosed by the demonstration of diagnostic Maltese cross pattern of starch particles.
Sclerosing encapsulating peritonitis
Intraperitoneal abscesses
  • Diagnosed best by CT scan of the abdomen.
  • Treatment consists of prompt and complete CT or US guided drainage of the abscess, control of the primary cause, and adjunctive use of effective antibiotics. Open drainage is reserved for abscesses for which percutaneous drainage is inappropriate or unsuccessful.
Peritoneal mesothelioma
peritoneal carcinomatosis
Differentiating secondary peritonitis from spontaneous bacterial peritonitis
Characteristic Spontaneous bacterial peritonitis Secondary peritonitis
Presentaion
  • Similar presentation but insidious onset unlike rapid onset in SBP
Microorganism
  • Polymicrobial involvement is common
  • Identifiable source of intra-abdominal infection, with or without perforation (surgically treatable source)[4]
Diagnostic criteria SBP is diagnosed in the presence of:[5] Diagnosed in the presence of
Follow-up paracentesis

References

  1. Wittmann DH, Schein M, Condon RE (1996). “Management of secondary peritonitis”. Ann Surg. 224 (1): 10–8. PMC 1235241. PMID 8678610.
  2. Nathens AB, Rotstein OD, Marshall JC (1998) Tertiary peritonitis: clinical features of a complex nosocomial infection. World J Surg 22 (2):158-63. PMID: 9451931
  3. Mishra SP, Tiwary SK, Mishra M, Gupta SK (2014) An introduction of Tertiary Peritonitis. J Emerg Trauma Shock 7 (2):121-3. DOI:10.4103/0974-2700.130883 PMID: 24812458
  4. Runyon BA, Hoefs JC (1984). “Ascitic fluid analysis in the differentiation of spontaneous bacterial peritonitis from gastrointestinal tract perforation into ascitic fluid”. Hepatology. 4 (3): 447–50. PMID 6724512.
  5. Runyon BA, Hoefs JC (1986). “Spontaneous vs secondary bacterial peritonitis. Differentiation by response of ascitic fluid neutrophil count to antimicrobial therapy”. Arch Intern Med. 146 (8): 1563–5. PMID 3729637.
  6. Runyon BA (1986). “Bacterial peritonitis secondary to a perinephric abscess. Case report and differentiation from spontaneous bacterial peritonitis”. Am J Med. 80 (5): 997–8. PMID 3518442.
  7. Akriviadis EA, Runyon BA (1990). “Utility of an algorithm in differentiating spontaneous from secondary bacterial peritonitis”. Gastroenterology. 98 (1): 127–33. PMID 2293571.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shivani Chaparala M.B.B.S [2]

Overview

Differential Diagnosis

Differentiating Secondary peritonitis from other causes of peritonitis
Disease Prominent clinical findings Lab tests Tratment
Primary peritonitis Spontaneous bacterial peritonitis
Tuberculous peritonitis
Continuous Ambulatory Peritoneal Dialysis (CAPD peritonitis)
Secondary peritonitis Acute bacterial secondary peritonitis
Biliary peritonitis
Tertiary peritonitis
Familial Mediterranean fever (periodic peritonitis, familial paroxysmal polyserositis)
  • Colchicine prevents but does not treat acute attacks.
Granulomatous peritonitis
  • Diagnosed by the demonstration of diagnostic Maltese cross pattern of starch particles.
Sclerosing encapsulating peritonitis
Intraperitoneal abscesses
  • Diagnosed best by CT scan of the abdomen.
  • Treatment consists of prompt and complete CT or US guided drainage of the abscess, control of the primary cause, and adjunctive use of effective antibiotics. Open drainage is reserved for abscesses for which percutaneous drainage is inappropriate or unsuccessful.
Peritoneal mesothelioma
peritoneal carcinomatosis

References

Template:WS Template:WH

Looking for the patient version?

Back to the patient-friendly article

© 2026 MyEClinic – IFTM Institut für Telematik in der Medizin GmbH