Makindo Medical Notes Comprehensive Medical Encyclopedia | Education for Healthcare Professionals

⚠️ Peritonitis = inflammation of the peritoneum (the serous membrane lining the abdominal cavity). It is a surgical emergency in most cases, as untreated infection can lead to sepsis and death. 👉 Causes include perforation, infection, trauma, or secondary to peritoneal dialysis.

📖 About

Inflammation of the peritoneum caused by bacterial or chemical irritation.
May be localised (around the source, e.g. perforated appendix) or generalised (diffuse contamination).
Primary (spontaneous) peritonitis occurs without a clear source – classic in cirrhotics with ascites.
Secondary peritonitis = due to intra-abdominal catastrophe (e.g. perforation, trauma, abscess).

⚡ Causes

🕳️ Perforated viscus: duodenal ulcer, perforated appendix, diverticulitis, bowel perforation, malignancy.
🦠 Infection: spontaneous bacterial peritonitis (SBP) in cirrhosis; peritoneal dialysis-related peritonitis.
💉 Trauma: blunt or penetrating abdominal trauma, post-op leaks.
🧪 Chemical: bile, blood, gastric acid, pancreatic enzymes in peritoneum.

🩺 Clinical Features

Severe abdominal pain + tenderness (often sudden onset).
🔒 Guarding and rigidity (“board-like abdomen”).
❌ Rebound tenderness (pain on release of pressure).
🤢 Nausea, vomiting, anorexia.
🌡️ Fever, tachycardia, hypotension → progressing to sepsis and shock.
Absent bowel sounds (paralytic ileus).

🔎 Investigations

🧪 Bloods: FBC (↑ WCC), CRP, U&E, LFTs, clotting, cultures.
🧪 Ascitic tap (if cirrhotic): neutrophils >250/mm³ = diagnostic of SBP.
📸 Imaging:
- Upright CXR: free air under diaphragm (perforation).
- Abdominal X-ray: dilated loops, free air.
- CT abdomen: localises source, free fluid, abscess.

🚑 Management

🔴 Resuscitation first: ABC, IV fluids, oxygen, NG tube, urinary catheter.
💉 Broad-spectrum IV antibiotics (cover Gram-negative + anaerobes).
🔪 Surgery (laparotomy/laparoscopy) for most secondary causes (perforation, abscess drainage).
SBP in cirrhotics: cefotaxime or ceftriaxone IV → secondary prophylaxis with oral norfloxacin/co-trimoxazole.
Peritoneal dialysis peritonitis: intraperitoneal antibiotics, catheter management.
Post-op: intensive monitoring, sepsis bundle, nutritional support.

⚠️ Complications

Sepsis and septic shock 🚨
Multi-organ failure (renal, respiratory, cardiovascular)
Intra-abdominal abscesses
Adhesions → bowel obstruction
Death if untreated (mortality high in elderly/cirrhotics)

🎯 Prognostic Factors

Age (elderly worse prognosis)
Underlying cause (perforated ulcer vs SBP)
Delay to surgery
Comorbidities (cirrhosis, renal failure, diabetes)

🛡 Prevention

Proton pump inhibitors for high-risk ulcer patients.
Good peritoneal dialysis technique (sterile precautions).
SBP prophylaxis in cirrhotics with low ascitic protein or previous SBP.

📚 Exam Pearls

SBP: ascitic neutrophils >250/mm³ = diagnostic.
Rigid, silent abdomen = classic generalised peritonitis.
CXR showing free gas under diaphragm = perforated viscus until proven otherwise.
Management is resuscitation + antibiotics + urgent surgery (except SBP).
Mortality in cirrhotics with SBP can be 30–40% despite treatment.

⚠️ Case 1 — Perforated Duodenal Ulcer

A 46-year-old man with a history of peptic ulcer disease presents with sudden severe epigastric pain radiating across the abdomen. He lies still, preferring not to move, and examination reveals board-like rigidity and absent bowel sounds. 💡 Perforated ulcer causes chemical peritonitis from gastric acid leakage, progressing to bacterial contamination. Erect CXR may show free subdiaphragmatic air. Urgent management includes IV fluids, antibiotics, NG decompression, and emergency surgery.

⚠️ Case 2 — Peritonitis from Ruptured Appendix

A 22-year-old man presents with 2 days of right iliac fossa pain, fever, and anorexia, now worsening to diffuse abdominal pain with guarding and rebound tenderness. 💡 Acute appendicitis can progress to perforation, releasing pus and faecal material into the peritoneum. This causes secondary bacterial peritonitis. Prompt diagnosis and surgical appendicectomy, alongside IV antibiotics and fluid resuscitation, are critical to prevent sepsis and abscess formation.

⚠️ Case 3 — Spontaneous Bacterial Peritonitis (SBP)

A 58-year-old man with decompensated alcoholic cirrhosis presents with fever, abdominal discomfort, and confusion. He has tense ascites, and paracentesis shows neutrophils >250/mm³. 💡 SBP occurs when gut bacteria translocate across the bowel wall into ascitic fluid. It is a medical emergency in cirrhotic patients, often presenting with subtle features such as encephalopathy. First-line treatment is IV third-generation cephalosporins (e.g. cefotaxime), with prophylactic antibiotics for high-risk patients.

Peritonitis