Peritonitis overview
Synonyms and keywords: Acute bacterial peritonitis, acute generalized peritonitis, acute peritonitis, abscess of suppurative peritonitis, acute suppurative peritonitis, purulent peritonitis, subphrenic peritonitis, pelvic peritonitis, acute serositis, aseptic peritonitis, chronic peritonitis, continuous ambulatory peritoneal dialysis associated peritonitis, fungal peritonitis, granulomatous peritonitis, peritoneal dialysis-associated peritonitis, serositis, chemical peritonitis, neonatal peritonitis, tuberculous peritonitis, peritoneal abscess, spontaneous bacterial peritonitis, benign paroxysmal peritonitis, pyogranulomatous serositis, perforation peritonitis, CAPD peritonitis, primary peritonitis, secondary peritonitis, tertiary peritonitis.
For more information related to Primary peritonitis click here
For more information related to Secondary peritonitis click here

# 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 (result of alcoholism), 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 is a emergency medical/surgical condition requiring prompt medical attention and treatment.

# Definition
Peritonitis is defined as inflammation of the peritoneum (a tissue that lines the inner wall of the abdominal cavity and covers most of the abdominal organs) from any cause. In contrast to peritonitis intrabdominal infection is defined as inflammation of peritoneum due to an infectious cause.

# Historical Perspective
- The first reports of SBP were seen in the German and French literatures between 1907 and 1958. Krencker 1907; Brule et al 1939; Cachin 1955; Navasa et al 1999 described that ascitic fluid infections were common in patients with liver cirrhosis. In 1963, Kerr and colleagues reported SBP as a complication in patients diagnosed with liver cirrhosis. Kerr and colleagues (1963) described 11 episodes of ascitic fluid infection in 9 cirrhotic patients. In 1964, Harold O.Conn introduced the term spontaneous bacterial peritonitis for the first time in English literature. 

# Classification
Peritonitis is classified based on the etiology, based on the ascitic fluid analysis and based on the clinical setting in which peritonitis is present. Commonly used classification is based on the etiology and is classified into 3 subtypes: primary peritonitis, secondary peritonitis, and tertiary peritonitis.

# Pathophysiology
Peritonitis results from contamination of normal sterile peritoneal cavity with infections or chemical irritants. Spillage of bile or gastric juices following a perforation of hollow viscus into the peritoneal cavity results in chemical peritonitis initially, which is followed by infection when bacteria enter and contaminate the peritoneal cavity. Bacterial peritonitis is usually caused by normal enteric flora such as E.coli, Klebsiella. Inflammatory process causes shift of fluid into the peritoneal cavity(third spacing) which leads to hypovolemia, septicemia and multi-organ failure resulting in death of the patient if not diagnosed early and treated adequately.

# Causes
There are two forms of peritonitis: Spontaneous bacterial peritonitis (SBP) is the result of an infection of the fluid in the peritoneal cavity. Liver or kidney failure can cause this condition. Patients on peritoneal dialysis for kidney failure are also at an increased risk for SBP.Secondary peritonitis is usually due to an infection that has spread from GI tract due to perforation of the hollow viscus.The most common cause of peritonitis are 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.

# Differential Diagnosis
Peritonitis has to be differentiated from other other diseases effecting the peritoneum such as peritoneal abscesses, peritoneal mesothelioma and peritoneal carcinomatosis which presents with ascites and abdominal pain.It also has to be differentiated from different forms of peritonitis like SBP, secondary peritonitis, tuberculous, CAPD peritonitis etc.Peritonitis also has to be differentiated from other causes of acute abdomen like appendicitis, diverticulitis etc.

# Epidemiology and Demographics

# Risk Factors
Patients with advanced liver and kidney disease are at an increased risk for SBP. Risk factors for liver disease include alcoholic cirrhosis and other diseases that lead to cirrhosis, such as viral hepatitis (Hepatitis B or C). Spontaneous peritonitis also occurs in patients who are on dialysis and chronic infections like tuberculosis.Secondary peritonitis results from rupture of a hollo viscus .

# Screening
There is no routine screening for peritonitis.

# Natural History, Complications and Prognosis
The prognosis depends on the cause of infection, clinical condition of the patient and the rate of progression of the disease before treatment.With timely and appropriate medical or surgical treatment for the control of local infection before it has spread systemically, patients usually do well. Without treatment, the outcome is usually poor because of entry of infection into the bloodstream causing shock and damage to other organs like kidney,liver and lung. However, in some cases, and patients with immunosuppression do poorly even with prompt and appropriate treatment.The potential complications of SBP include: progression of the liver disease leading to hepatic encephalopathy and kidney failure from hepatic-renal syndrome and sepsis.The potential complications of secondary peritonitis are progression to intra abdominal abscess, intra-peritoneal adhesions, and septic shock.

# Diagnosis

## History and Symptoms
The main manifestations of peritonitis are acute abdominal pain.

## Physical Examination
tenderness, and guarding, which are exacerbated by moving the peritoneum, e.g. coughing, flexing the hips, or eliciting the Blumberg sign (a.k.a. rebound tenderness, meaning that pressing a hand on the abdomen elicits pain, but releasing the hand abruptly will aggravate the pain, as the peritoneum snaps back into place). Abdominal pain and tenderness: The localization of these manifestations depends on whether peritonitis is localized (e.g. appendicitis or diverticulitis before perforation), or generalized to the whole abdomen; even in the latter case, pain typically starts at the site of the causing disease. Peritonitis is an example of acute abdomen.

## Laboratory Findings
A diagnosis of peritonitis is based primarily on clinical grounds, that is on the clinical manifestations described above; if they support a strong suspicion of peritonitis, no further investigation should delay surgery. Leukocytosis and acidosis may be present, but they are not specific findings.

## Imaging Findings
Plain abdominal X-rays may reveal dilated, oedematous intestines, although it is mainly useful to look for pneumoperitoneum (free air in the peritoneal cavity), which may also be visible on chest X-rays. If reasonable doubt still persists, an exploratory peritoneal lavage may be performed (e.g. in cause of trauma, in order to look for white blood cells, red blood cells, or bacteria).

## Other Diagnostic Studies

# Treatment

## Medical Therapy
Antibiotic therapy is the mainstay of treatment for spontaneous bacterial peritonitis.

## Surgery
Surgery (laparotomy) is needed to perform a full exploration and lavage of the peritoneum, as well as to correct any gross anatomical damage which may have caused peritonitis. The exception is spontaneous bacterial peritonitis, which does not benefit from surgery.

## Prevention
Prevention of peritonitis depends on the form of peritonitis.