Peritonitis

Gastroenterology (12%) Core Clinical Conditions

1B The Physician Associate is able to identify the condition as a possible diagnosis: may not have the knowledge/resources to confirm the diagnosis or to manage the condition safely, but can take measures to avoid immediate deterioration and refer appropriately.

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Definition Aetiology Pathophysiology Risk factor Sign and Symptoms Investigations Management

Peritonitis is a medical condition characterised by inflammation of the peritoneum, which is the thin membrane lining the inner wall of the abdomen and covering the organs within it. It is a serious and potentially life-threatening condition that requires immediate medical attention and treatment.

1. Gastrointestinal Perforation: When the gastrointestinal tract is compromised by conditions like peptic ulcers, diverticulitis, or appendicitis, the bacteria present in the gut can leak into the peritoneum, triggering an inflammatory response.
2. Ruptured or Infected Organs: If an organ within the abdomen, such as the appendix or gallbladder, becomes infected or ruptures due to conditions like cholecystitis or appendicitis, bacteria can spill into the peritoneal cavity and cause peritonitis.
3. Intraperitoneal Catheters: Individuals with long-term intraperitoneal catheters, commonly used for dialysis or intra-abdominal chemotherapy, are at increased risk of developing peritonitis. The catheters provide a direct pathway for bacteria to enter the peritoneum.

Infection and Inflammation:
Peritonitis typically occurs when a breach in the gastrointestinal tract allows bacteria or other microorganisms to enter the peritoneal cavity. This can be due to conditions such as perforated ulcers, diverticulitis, appendicitis, or abdominal trauma. Once inside the peritoneum, the microorganisms trigger an initial inflammatory response.
Vascular Response:
Upon infection, the blood vessels in the peritoneum undergo a series of changes that contribute to the pathophysiology of peritonitis. The arterioles dilate, leading to increased blood flow to the affected area. This allows immune cells like neutrophils and macrophages to migrate to the site of infection, helping to combat the invading pathogens. Simultaneously, the venules become more permeable, facilitating the leakage of plasma and immune cells into the peritoneal cavity.
Release of Inflammatory Mediators:
The invasion of microorganisms triggers the release of various pro-inflammatory mediators, such as cytokines (e.g., interleukins, tumour necrosis factor-alpha) and chemokines. These mediators further promote vasodilation, vascular permeability, and recruit additional immune cells to the site of infection. However, excessive release of these inflammatory mediators may lead to an uncontrolled inflammatory response, causing collateral damage to the peritoneum and surrounding tissues.
Fluid Shift and Exudate Formation:
As a result of increased vascular permeability and inflammation, fluid begins to accumulate in the peritoneal cavity. This fluid shift is a response to dilute the toxins and microorganisms released during the infection. The fluid, known as exudate, contains a high concentration of inflammatory cells, fibrin, and proteins. It acts as a defence mechanism to wall off the infection and restrict its spread. However, an excessive accumulation of exudate can contribute to abdominal distension and impair normal organ function.
Systemic Effects:
The inflammatory response triggered by peritonitis can have wide-ranging systemic effects. The release of pro-inflammatory mediators, such as cytokines, can lead to a systemic inflammatory response syndrome (SIRS), characterised by fever, tachycardia, increased respiratory rate, and altered white blood cell count. If left untreated, severe peritonitis can progress to septic shock, organ failure, and death.

1. Trauma: Blunt or penetrating trauma to the abdomen can cause damage to the peritoneum, leading to peritonitis. This can occur due to abdominal injuries from accidents, gunshot wounds, or surgical complications.
2. Gastrointestinal Perforations: Perforations caused by foreign bodies, such as ingested sharp objects or iatrogenic injuries during endoscopic procedures, can introduce bacteria into the peritoneal cavity.
3. Underlying Medical Conditions: Certain medical conditions, such as peritoneal dialysis, cirrhosis, abdominal cancer, and autoimmune diseases like lupus, increase the likelihood of developing peritonitis.
4. Compromised Immune System: Individuals with weakened immune systems due to conditions like HIV/AIDS, chemotherapy, or immunosuppressant medications have an increased susceptibility to infections, including those causing peritonitis.

1. Abdominal Pain: One of the primary symptoms of peritonitis is intense and persistent abdominal pain. The pain is usually localised and can be diffused or concentrated in a specific area. It may initially start as a general discomfort and progressively worsen over time.
2. Tenderness: The abdomen becomes extremely tender and sensitive to touch. The affected person may flinch or recoil when pressure is applied to the abdomen.
3. Swelling or Distention: The area around the abdomen may appear swollen or distended. This can occur due to the inflammation and fluid accumulation in the peritoneum.
4. Fever: Peritonitis often causes an elevated body temperature, resulting in a fever. The body tries to fight off the infection, leading to an increased body temperature.
5. Nausea and Vomiting: Many individuals with peritonitis experience persistent nausea and may vomit repeatedly. This is due to the irritation caused by the inflammation.
6. Loss of Appetite: As a result of the abdominal pain and discomfort, individuals may have a decreased or complete loss of appetite.
7. Fatigue and Weakness: Peritonitis can cause a general feeling of fatigue and weakness. This may be due to the body's response to the infection and inflammation, causing systemic effects.
8. Altered Bowel Movements: Peritonitis can lead to changes in bowel movements, such as diarrhoea or constipation. The digestive system may be affected, causing irregularities in stool consistency and frequency.
9. Increased Heart Rate: Individuals with peritonitis often experience an elevated heart rate or palpitations. This is because the body is trying to compensate for the infection and maintain the required blood flow.
10. Difficulty Breathing: In severe cases, peritonitis can cause difficulty breathing. This may be due to the inflammation pushing against the diaphragm, limiting its movement and causing respiratory distress.

1. Medical History and Physical Examination

Ask patients about signs and symptoms of peritonitis.
During the physical examination, examine the abdomen for signs of tenderness, rigidity, distension, or muscle guarding. These findings may suggest the presence of peritonitis. The examination may also reveal other associated symptoms such as fever, rapid heart rate, and a decrease in blood pressure.

2. Laboratory Tests

• Full Blood Count (FBC): This test helps to identify if there is an increased white blood cell count, a commonly observed inflammatory response in peritonitis.

• Blood Cultures: Obtaining blood samples for culture and sensitivity testing can help identify the specific bacteria or fungi causing the infection.

• Peritoneal Fluid Analysis: Through a procedure called paracentesis, a small sample of peritoneal fluid is collected and sent for analysis. This test helps determine the presence of bacteria and their sensitivity to antibiotics.

• Liver and Renal Function Tests: These tests evaluate the overall functioning of the liver and kidney, which might be affected in cases of severe peritonitis.

3. Imaging Studies

• Abdominal X-ray: A simple X-ray may reveal signs of bowel obstruction, perforation, or the presence of free air within the abdominal cavity.

• Ultrasound: This non-invasive imaging technique can help identify any abscesses, fluid collections, or abnormal findings in the abdomen.

• Computed Tomography (CT) Scan: CT scans provide detailed images of the abdominal organs and can help identify the source of infection, abscesses, or other complications associated with peritonitis.

4. Exploratory Surgery

In some cases, where the diagnosis of peritonitis remains uncertain, and imaging studies fail to provide a definite answer, exploratory surgery may be necessary. During surgery, the surgeon visually inspects the abdominal cavity, checks for evidence of infection, and takes tissue or fluid samples for further analysis.

1. IV Antibiotic Therapy:
Once peritonitis is diagnosed, the immediate initiation of appropriate antibiotic therapy is crucial. Empirical antibiotic treatment, based on the likely causative organisms, should be started initially and later adjusted based on the culture results.
2. Surgical Intervention:
Surgical intervention may be necessary in certain cases of peritonitis, especially when an abscess, perforation, or necrotic tissue is present. Exploratory laparotomy or laparoscopy allows direct visualisation of the abdominal cavity, identification, and correction of the source of infection, and removal of any necrotic or infected tissues. Drainage of abscesses and primary closure of perforations are commonly performed during the surgical procedure.
Post-surgical management includes antibiotic therapy, wound care, pain management, and monitoring for any signs of complications. Patients undergoing surgery for peritonitis often require a multidisciplinary approach, with input from surgeons, intensivists, and infectious disease specialists.

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