Peritonitis

Overview

Peritonitis is a serious, life-threatening infection of the peritoneum, the thin, silk-like membrane that lines the inner abdominal wall and covers most of the abdominal organs. This condition represents a medical emergency that requires immediate hospitalization and aggressive treatment to prevent potentially fatal complications.

The peritoneum serves multiple important functions, including producing peritoneal fluid that lubricates abdominal organs and facilitates their movement during digestion and breathing. When this membrane becomes infected, it can lead to widespread inflammation, organ dysfunction, and systemic complications including sepsis and septic shock.

Peritonitis can be classified as primary (spontaneous) or secondary (caused by perforation or rupture of an abdominal organ). Secondary peritonitis is more common and typically results from conditions such as appendicitis, perforated ulcers, or complications from abdominal surgery. Early recognition and prompt treatment are crucial for favorable outcomes, as delays can result in severe complications and increased mortality risk.

Symptoms

The symptoms of peritonitis typically develop rapidly and can quickly become severe. Recognition of these warning signs is crucial for seeking immediate medical attention.

Primary Symptoms

Additional Symptoms

• Shortness of breath due to abdominal distension
• Groin tenderness or mass in some cases
• Intermenstrual bleeding in women (rare)
• Side pain extending from the abdomen

Abdominal Signs

• Severe tenderness when touching the abdomen
• Abdominal rigidity (board-like stiffness)
• Rebound tenderness (pain when pressure is released)
• Abdominal distension and bloating
• Inability to pass gas or have bowel movements
• Guarding (involuntary muscle contraction when abdomen is touched)

Systemic Symptoms

• High fever (often above 101°F/38.3°C)
• Chills and shaking
• Rapid heart rate (tachycardia)
• Low blood pressure
• Rapid, shallow breathing
• Profuse sweating
• Feeling faint or dizzy

Signs of Sepsis

Advanced peritonitis can lead to sepsis with these warning signs:

• Confusion or altered mental state
• Extreme weakness and fatigue
• Decreased urine output
• Skin discoloration (pale, mottled, or cyanotic)
• Cold, clammy skin
• Severe drop in blood pressure
• Organ dysfunction

Symptom Progression

Peritonitis symptoms typically follow this pattern:

• Early stage: Localized abdominal pain and tenderness
• Progressive stage: Worsening pain, fever, nausea, vomiting
• Advanced stage: Systemic symptoms, signs of sepsis
• Critical stage: Organ failure, shock, life-threatening complications

Special Considerations

Elderly Patients

• May have milder initial symptoms
• Confusion may be an early sign
• Fever may be absent or minimal
• Faster progression to serious complications

Immunocompromised Patients

• Symptoms may be masked or delayed
• Fever may be absent despite serious infection
• Rapid progression to sepsis
• Higher risk of complications

Causes

Peritonitis is caused by bacterial or fungal infection of the peritoneum. The infection can occur through several different mechanisms, categorized as primary or secondary peritonitis.

Primary (Spontaneous) Peritonitis

Primary peritonitis occurs without an obvious intra-abdominal source of infection:

• Spontaneous bacterial peritonitis (SBP): Common in patients with cirrhosis and ascites
• Hematogenous spread: Bacteria traveling through the bloodstream
• Lymphatic spread: Infection spreading through lymphatic vessels
• Transmural migration: Bacteria crossing intestinal wall without perforation

Common Organisms in Primary Peritonitis

• Escherichia coli (E. coli)
• Klebsiella pneumoniae
• Streptococcus pneumoniae
• Enterococcus species

Secondary Peritonitis

Secondary peritonitis results from perforation or rupture of an abdominal organ:

Gastrointestinal Causes

• Perforated appendicitis: Most common cause in young adults
• Perforated peptic ulcer: Stomach or duodenal ulcer rupture
• Perforated diverticulitis: Rupture of infected diverticula
• Bowel perforation: From trauma, ischemia, or inflammatory bowel disease
• Gallbladder perforation: Severe cholecystitis

Gynecological Causes

• Pelvic inflammatory disease (PID): Spread of infection from reproductive organs
• Ruptured ovarian cyst: Especially infected cysts
• Ectopic pregnancy rupture: Leading to bleeding and infection
• Post-abortion complications: Uterine perforation or infection

Trauma-Related Causes

• Penetrating abdominal wounds
• Blunt abdominal trauma with organ rupture
• Foreign body perforation
• Surgical complications

Surgical Complications

• Anastomotic leak after bowel surgery
• Accidental bowel perforation during surgery
• Post-operative infection
• Complications from laparoscopic procedures

Medical Device-Related Causes

• Peritoneal dialysis: Catheter-related infections
• Feeding tubes: Perforation or migration
• Drainage tubes: Contamination or perforation
• Intraperitoneal catheters: For chemotherapy or other treatments

Other Causes

• Pancreatitis: Severe cases with pancreatic necrosis
• Mesenteric ischemia: Bowel death leading to perforation
• Inflammatory bowel disease: Crohn's disease or ulcerative colitis complications
• Malignancy: Tumor perforation or treatment complications
• Vascular causes: Mesenteric thrombosis or embolism

Microbiology

Secondary Peritonitis Organisms

• Gram-negative bacteria: E. coli, Bacteroides, Klebsiella
• Gram-positive bacteria: Enterococcus, Streptococcus
• Anaerobic bacteria: Bacteroides fragilis, Clostridium
• Fungi: Candida species (in immunocompromised patients)

Risk Factors for Specific Causes

• Age: Appendicitis more common in young adults
• Liver disease: Increases risk of spontaneous bacterial peritonitis
• Immunosuppression: Higher risk of all types
• Previous abdominal surgery: Adhesions and complications
• Medical comorbidities: Diabetes, cancer, kidney disease

Risk Factors

Several factors can increase the risk of developing peritonitis:

Medical Conditions

Liver Disease

• Cirrhosis with ascites (highest risk for spontaneous bacterial peritonitis)
• Portal hypertension
• Liver failure
• Previous episodes of spontaneous bacterial peritonitis
• Low protein levels in ascitic fluid

Gastrointestinal Conditions

• Inflammatory bowel disease (Crohn's disease, ulcerative colitis)
• Diverticulitis
• Peptic ulcer disease
• Appendicitis
• Cholecystitis

Immunocompromising Conditions

• Diabetes mellitus
• HIV/AIDS
• Cancer and chemotherapy
• Organ transplant recipients
• Chronic steroid use
• Immunosuppressive medications

Medical Procedures and Devices

• Peritoneal dialysis: Catheter-related infection risk
• Abdominal surgery: Especially emergency procedures
• Endoscopic procedures: Colonoscopy, endoscopy with perforation risk
• Intraperitoneal devices: Catheters, drainage tubes
• Paracentesis: Procedure to drain ascitic fluid

Demographic Risk Factors

• Age: Very young and elderly at higher risk
• Gender: Some causes more common in women (PID, ectopic pregnancy)
• Pregnancy: Risk of ectopic pregnancy rupture
• Premature infants: Higher risk of necrotizing enterocolitis

Lifestyle and Environmental Factors

• Alcohol abuse: Leading to liver disease and immunosuppression
• Poor hygiene: Especially with peritoneal dialysis
• Malnutrition: Impaired immune function
• High-risk sexual behavior: Increased risk of PID

Previous Medical History

• Previous episode of peritonitis
• History of abdominal trauma
• Previous perforated organ
• Chronic ascites
• Recurrent urinary tract infections

Medication-Related Risk Factors

• NSAIDs: Increased risk of peptic ulcer perforation
• Corticosteroids: Immunosuppression and delayed healing
• Anticoagulants: May complicate surgical treatment
• Proton pump inhibitors: May mask ulcer symptoms

Anatomical Risk Factors

• Congenital abnormalities of abdominal organs
• Previous abdominal adhesions
• Hernias with incarceration risk
• Anatomical variants predisposing to organ perforation

High-Risk Situations

• Recent abdominal surgery
• Hospitalization in intensive care unit
• Multiple organ failure
• Prolonged mechanical ventilation
• Multiple invasive procedures

Diagnosis

Diagnosing peritonitis requires rapid assessment combining clinical evaluation, laboratory tests, and imaging studies. Early diagnosis is crucial for optimal outcomes.

Clinical Assessment

History Taking

• Symptom onset: Timing, progression, and character of pain
• Associated symptoms: Fever, nausea, vomiting, changes in bowel habits
• Medical history: Previous surgeries, chronic conditions, medications
• Recent procedures: Surgery, endoscopy, peritoneal dialysis
• Social history: Alcohol use, sexual history (for PID risk)

Physical Examination

• Vital signs: Fever, tachycardia, hypotension, tachypnea
• General appearance: Distress level, positioning, mental state
• Abdominal examination:
  • Inspection for distension, surgical scars
  • Auscultation for bowel sounds
  • Palpation for tenderness, masses, rigidity
  • Percussion for ascites, organ enlargement
  • Assessment for rebound tenderness and guarding
• Rectal examination: If clinically indicated
• Pelvic examination: In women, if gynecological cause suspected

Laboratory Tests

Blood Tests

• Complete blood count (CBC): Elevated white blood cell count
• Blood cultures: To identify causative organisms
• Basic metabolic panel: Electrolyte imbalances, kidney function
• Liver function tests: Especially if liver disease suspected
• Lactate level: Marker of tissue hypoperfusion
• Procalcitonin: Inflammatory marker for bacterial infection
• Coagulation studies: If surgery anticipated

Peritoneal Fluid Analysis

If ascites is present, diagnostic paracentesis should be performed:

• Cell count: >250 neutrophils/mm³ suggests bacterial infection
• Gram stain and culture: Identify causative organisms
• Protein and albumin: Calculate serum-ascites albumin gradient
• Glucose: Low levels suggest bacterial infection
• LDH: Elevated in infection

Imaging Studies

X-rays

• Upright chest X-ray: Free air under diaphragm (pneumoperitoneum)
• Abdominal X-ray: Bowel obstruction patterns, foreign bodies
• Limited sensitivity for peritonitis diagnosis

CT Scan

• Most useful imaging study for peritonitis evaluation
• Can identify:
  • Source of infection (perforated organ)
  • Extent of peritoneal involvement
  • Presence of abscesses
  • Free fluid in abdomen
  • Complications (bowel obstruction)
• Contrast-enhanced CT provides better detail

Ultrasound

• Useful for detecting free fluid (ascites)
• Can guide paracentesis procedure
• May identify gallbladder or gynecological causes
• Limited by bowel gas and operator dependence

Specialized Tests

• MRI: When CT is contraindicated or for specific indications
• Nuclear medicine scans: To locate infection source
• Endoscopy: To evaluate for gastrointestinal perforation
• Laparoscopy: Diagnostic and potentially therapeutic

Diagnostic Criteria

Spontaneous Bacterial Peritonitis

• Ascitic fluid neutrophil count >250 cells/mm³
• Compatible clinical presentation
• Positive ascitic fluid culture (in 50-70% of cases)
• No evidence of intra-abdominal source

Secondary Peritonitis

• Evidence of intra-abdominal source on imaging
• Polymicrobial infection in peritoneal fluid
• Elevated peritoneal fluid glucose or protein
• Clinical signs of perforation

Differential Diagnosis

Conditions to consider:

• Acute pancreatitis
• Bowel obstruction
• Mesenteric ischemia
• Pelvic inflammatory disease
• Ruptured aortic aneurysm
• Myocardial infarction (can mimic abdominal pain)

Scoring Systems

• SOFA score: Assess organ dysfunction severity
• APACHE II: Predict mortality risk
• Mannheim Peritonitis Index: Assess peritonitis severity

Treatment Options

Treatment of peritonitis requires immediate, aggressive management including antibiotics, supportive care, and often surgical intervention. The approach depends on the type and severity of peritonitis.

Emergency Management

Initial Stabilization

• IV access: Large-bore intravenous lines for fluid resuscitation
• Fluid resuscitation: Crystalloid solutions to maintain blood pressure
• Oxygen therapy: Support respiratory function
• Pain management: Appropriate analgesics
• Monitoring: Continuous vital signs, urine output

Immediate Interventions

• NPO (nothing by mouth) status
• Nasogastric decompression if vomiting or distension
• Urinary catheter for monitoring output
• Blood type and crossmatch
• Consent for surgery if needed

Antibiotic Therapy

Empirical Antibiotics

Start immediately, before culture results:

• Broad-spectrum coverage: Gram-positive, gram-negative, and anaerobic bacteria
• Common regimens:
  • Piperacillin-tazobactam
  • Cefepime + metronidazole
  • Carbapenem (meropenem, imipenem)
  • Fluoroquinolone + metronidazole + ampicillin
• Antifungal therapy: Consider in high-risk patients

Targeted Therapy

• Adjust based on culture and sensitivity results
• De-escalate to narrower spectrum when appropriate
• Duration typically 7-14 days
• IV route initially, may switch to oral when stable

Surgical Management

Indications for Surgery

• Secondary peritonitis: Source control required
• Organ perforation: Repair or resection needed
• Abscess formation: Drainage required
• Bowel obstruction: Mechanical relief needed
• Clinical deterioration: Despite medical management

Surgical Procedures

• Exploratory laparotomy: Open surgical exploration
• Laparoscopy: Minimally invasive approach when appropriate
• Source control:
  • Appendectomy for perforated appendicitis
  • Bowel resection for perforated bowel
  • Cholecystectomy for perforated gallbladder
  • Repair of perforated ulcer
• Peritoneal lavage: Wash out infected material
• Drainage: Placement of drains if needed

Supportive Care

Intensive Care Management

• Hemodynamic support: Vasopressors if shock present
• Respiratory support: Mechanical ventilation if needed
• Renal support: Dialysis for acute kidney injury
• Nutritional support: Parenteral or enteral nutrition

Organ Support

• Cardiovascular: Fluid management, inotropes
• Pulmonary: Oxygen, ventilation support
• Renal: Maintain perfusion, avoid nephrotoxins
• Hepatic: Monitor function, avoid hepatotoxins
• Hematologic: Correct coagulopathy

Specific Treatment by Type

Primary Peritonitis (SBP)

• Third-generation cephalosporin (ceftriaxone, cefotaxime)
• Alternative: fluoroquinolone
• Duration: 5-10 days
• No surgery typically required
• Prophylaxis for recurrence

Secondary Peritonitis

• Broad-spectrum antibiotics
• Urgent surgical intervention
• Source control essential
• Longer antibiotic course (7-14 days)

Peritoneal Dialysis-Related Peritonitis

• Intraperitoneal antibiotics: Through dialysis catheter
• Common regimens: Vancomycin + ceftazidime or aminoglycoside
• Catheter management: May require removal in severe cases
• Temporary hemodialysis: If catheter removed

Complications Management

• Septic shock: Aggressive fluid resuscitation, vasopressors
• ARDS: Mechanical ventilation with lung-protective strategies
• Acute kidney injury: Fluid optimization, dialysis if needed
• Abdominal compartment syndrome: Decompressive surgery
• Enterocutaneous fistula: Conservative or surgical management

Monitoring and Follow-up

• Serial clinical assessments
• Laboratory monitoring (CBC, chemistry, lactate)
• Imaging if clinical deterioration
• Adjustment of therapy based on response
• Long-term follow-up for complications

Prevention

While not all cases of peritonitis can be prevented, many can be avoided through proper medical care, infection prevention measures, and early treatment of underlying conditions.

Primary Prevention of Spontaneous Bacterial Peritonitis

High-Risk Patients with Ascites

• Antibiotic prophylaxis: For patients with:
  • Previous episode of SBP
  • Low ascitic protein (<1.5 g/dL)
  • Advanced liver disease
  • Gastrointestinal bleeding
• Prophylactic antibiotics: Norfloxacin, ciprofloxacin, or trimethoprim-sulfamethoxazole
• Regular monitoring: Serial paracentesis in high-risk patients

Prevention of Secondary Peritonitis

Early Treatment of Underlying Conditions

• Appendicitis: Prompt surgical evaluation and treatment
• Diverticulitis: Appropriate antibiotic therapy and monitoring
• Cholecystitis: Timely cholecystectomy
• Peptic ulcer disease: H. pylori eradication, PPI therapy
• IBD: Optimal medical management

Medication Management

• NSAIDs: Use with caution, especially in elderly or those with ulcer history
• Proton pump inhibitors: For patients on NSAIDs or with ulcer risk
• H. pylori testing: And treatment when appropriate
• Avoid unnecessary antibiotics: To prevent resistance

Surgical Prevention

Perioperative Measures

• Prophylactic antibiotics: Appropriate timing and selection
• Sterile technique: Strict adherence to aseptic principles
• Careful tissue handling: Minimize trauma and contamination
• Adequate hemostasis: Control bleeding to prevent hematoma
• Proper wound closure: Appropriate technique and materials

Post-operative Care

• Early recognition of complications
• Appropriate drain management
• Wound care and monitoring
• Early mobilization when appropriate

Peritoneal Dialysis Prevention

Infection Prevention Measures

• Proper training: Patient and caregiver education
• Hand hygiene: Thorough handwashing before procedures
• Sterile technique: During catheter care and exchanges
• Exit site care: Daily cleaning and inspection
• Regular monitoring: For signs of infection

Catheter Management

• Proper catheter placement and tunneling
• Appropriate break-in period
• Regular assessment of catheter function
• Prompt treatment of exit site infections

General Prevention Strategies

Risk Factor Modification

• Alcohol cessation: To prevent liver disease progression
• Diabetes management: Optimal glucose control
• Immunization: Appropriate vaccines for immunocompromised patients
• Nutrition optimization: Maintain good nutritional status

Medical Surveillance

• Regular medical follow-up for chronic conditions
• Monitoring for complications of liver disease
• Screening for malignancies that may perforate
• Assessment of medication side effects

Patient Education

• Warning signs: Recognition of symptoms requiring immediate attention
• Medication compliance: Importance of adherence to prescribed therapy
• Follow-up care: Keeping scheduled appointments
• Lifestyle modifications: Diet, alcohol, smoking cessation
• Infection prevention: General hygiene measures

Healthcare System Prevention

• Quality improvement: Protocols for high-risk procedures
• Antibiotic stewardship: Appropriate use to prevent resistance
• Surveillance systems: Monitor for healthcare-associated infections
• Staff training: Regular education on infection prevention

When to See a Doctor

Peritonitis is a medical emergency that requires immediate attention. Recognizing the warning signs and seeking prompt care can be life-saving.

Call 911 or Go to Emergency Room Immediately

• Severe abdominal pain: Especially if sudden onset or worsening
• Rigid, board-like abdomen: Indicating peritoneal irritation
• High fever: >101°F (38.3°C) with abdominal pain
• Signs of shock: Rapid pulse, low blood pressure, dizziness
• Difficulty breathing: Due to abdominal distension or pain
• Altered mental state: Confusion, lethargy, or decreased responsiveness
• Severe nausea and vomiting: Especially if unable to keep fluids down
• No bowel movements or gas: With abdominal pain and distension

Seek Immediate Medical Attention

• Persistent severe abdominal pain lasting more than 6 hours
• Fever with abdominal tenderness
• Vomiting that prevents keeping fluids down
• Signs of dehydration (decreased urination, dry mouth, weakness)
• Abdominal pain that worsens when moving or coughing
• Abdominal distension with pain
• Any combination of fever, abdominal pain, and vomiting

High-Risk Patients Requiring Urgent Care

Patients with Liver Disease

• Any new abdominal pain or tenderness
• Fever in patients with ascites
• Confusion or altered mental state
• Worsening of existing ascites
• Any signs of infection

Peritoneal Dialysis Patients

• Cloudy dialysis fluid: Most important early sign
• Abdominal pain during or after dialysis
• Fever with dialysis
• Nausea or vomiting during dialysis
• Exit site infection signs
• Catheter drainage problems

Post-Surgical Patients

• New or worsening abdominal pain after surgery
• Fever developing days after surgery
• Wound drainage or separation
• Inability to tolerate food or fluids
• Distension or change in bowel habits

Immunocompromised Patients

• Any abdominal symptoms, even if mild
• Fever without obvious source
• Subtle changes in condition
• Unexplained weakness or fatigue

When to Contact Your Doctor

• Mild abdominal pain that persists or worsens
• Low-grade fever with abdominal discomfort
• Changes in bowel habits with abdominal symptoms
• Concerns about medication side effects
• Questions about symptoms in high-risk conditions

Prevention-Related Medical Care

Regular Follow-up Needed

• Patients with cirrhosis and ascites
• Peritoneal dialysis patients
• History of inflammatory bowel disease
• Previous episodes of peritonitis
• Immunocompromised patients

What NOT to Do While Waiting for Care

• Don't eat or drink: May need emergency surgery
• Don't take pain medications: May mask important symptoms
• Don't apply heat: To the abdomen
• Don't take laxatives: May worsen condition
• Don't delay: Seeking medical attention

Information to Provide to Medical Team

• Exact timing and character of symptoms
• Medical history, especially abdominal surgeries
• Current medications
• Recent procedures or hospitalizations
• Any known allergies
• Family history of abdominal conditions

Family and Caregiver Actions

• Monitor patient's condition closely
• Be prepared to call emergency services
• Gather medical information and medications
• Don't leave patient alone if condition is concerning
• Be advocate for prompt medical evaluation

Related Conditions

Peritonitis is associated with several conditions that either predispose to its development or result from complications:

Predisposing Conditions

• Peptic ulcer disease
• Inflammatory bowel disease
• Cholecystitis
• Pancreatitis
• Mesenteric ischemia
• Pelvic inflammatory disease

Complications and Sequelae

• Septic shock
• ARDS
• Acute kidney injury
• Multi-organ failure
• Intra-abdominal abscess
• Bowel obstruction from adhesions

Associated Surgical Conditions

• Anastomotic leak
• Wound dehiscence
• Enterocutaneous fistula
• Short bowel syndrome
• Incisional hernia

Related Infections

• Intra-abdominal abscess
• Necrotizing fasciitis
• C. difficile colitis
• Ascending cholangitis
• Severe pyelonephritis

Chronic Conditions

• Chronic peritonitis
• Sclerosing peritonitis
• Peritoneal carcinomatosis
• Chronic abdominal pain
• Malnutrition from chronic illness

References

1. American Association for the Study of Liver Diseases. Practice Guidelines for Spontaneous Bacterial Peritonitis. AASLD. 2024.
2. Surgical Infection Society. Guidelines for Management of Intra-abdominal Infections. SIS. 2023.
3. International Society for Peritoneal Dialysis. Peritonitis Guidelines. ISPD. 2024.
4. World Journal of Emergency Surgery. Management of Secondary Peritonitis. 2023.
5. Critical Care Medicine. Sepsis and Septic Shock in Peritonitis. 2024.