Study sheet: Intra-Abdominal Infections

📋 Course Outline

1. General Features and Microbiology
2. Acute Appendicitis
3. Peritonitis
4. Sigmoid Diverticulitis
5. Biliary Tract Infections
6. Hepatic Abscesses
7. Urgent Diagnostic and Therapeutic Principles

📖 1. General Features and Microbiology

🔑 Key Concepts & Definitions

• Acute appendicitis : usually caused by intraluminal obstruction followed by mucosal inflammation and bacterial superinfection

📝 Essential Points

• Intra-abdominal infections are most often medical-surgical emergencies with a frequently life-threatening prognosis.

• The reference examination for intra-abdominal infection is computed tomography, sometimes supplemented by ultrasonography.

• The main microorganisms are:

  • Enterobacteriaceae
  • anaerobes
  • enterococci

💡 Memory Hook

Abdominal infection → urgent medical-surgical management

📖 2. Acute Appendicitis

📝 Essential Points

• Acute appendicitis occurs most often between 10 and 25 years of age.

• Typical appendicitis findings include right iliac fossa pain and tenderness or guarding, fever of 38–38.5°C, constipation, nausea, vomiting, and painful rectal examination.

• 🔄 Management consists of: emergency surgery, possible laparoscopy, antibiotic treatment adapted to operative findings and complications

💡 Memory Hook

Obstruction → mucosal inflammation → bacterial superinfection

📖 3. Peritonitis

🔑 Key Concepts & Definitions

• Peritonitis : localized or generalized inflammation of the peritoneum, the serous membrane lining the abdominopelvic cavity and covering its viscera

📝 Essential Points

• The main categories are: secondary peritonitis from an intra-abdominal infectious focus, primary peritonitis from a hematogenous infection, iatrogenic peritonitis after laparoscopy or peritoneal dialysis

• Clinical signs of peritonitis include initially localized then diffuse abdominal pain, abdominal rigidity described as a board-like abdomen, fever, painful Douglas pouch examination, cessation of stool and gas, nausea, and vomiting.

• 🔄 Management includes:

  1. peritoneal lavage and drainage
  2. microbiological sampling
  3. treatment of digestive perforation
  4. supportive medical care
  5. empirical then adapted antibiotics

• Antibiotic treatment lasts 2–3 days for mild community-acquired peritonitis, 4 days for generalized forms, and 8 days for postoperative nosocomial forms.

💡 Memory Hook

Secondary peritonitis has an intra-abdominal focus, whereas primary peritonitis is hematogenous

📖 4. Sigmoid Diverticulitis

🔑 Key Concepts & Definitions

• Sigmoid diverticulitis : an infection of colonic diverticula that occurs most often between 60 and 70 years of age and is rare before 30 years

★ Must-know

• Typical sigmoid diverticulitis presents with left iliac fossa pain, fever of 38–38.5°C, constipation, localized left iliac fossa guarding, and painful rectal examination.

📌 Treatment is usually 7 days of empirical antibiotics, but spontaneously favorable uncomplicated disease may receive symptomatic treatment without antibiotics; surgery is reserved for complications such as abscess or perforation.

Further detail

• The main complications are:
  • perforation with peritonitis
  • abscess
  • stenosis causing obstruction
  • diverticular bleeding causing rectal bleeding

📖 5. Biliary Tract Infections

🔑 Key Concepts & Definitions

• Acute cholecystitis : acute infection of the gallbladder caused by prolonged obstruction of the cystic duct by a stone or another obstacle
• Acute cholangitis : infection associated with an obstruction of the main bile duct and classically presents with right hypochondrial or epigastric pain, fever, and jaundice

★ Must-know

• Biliary tract infections are mainly caused by obstruction from gallstones or tumors and more rarely by parasites such as flukes or hydatidosis.

• Acute cholecystitis typically causes high fever with chills, sudden intense right hypochondrial pain, a positive Murphy sign, and possible radiation to the back, right shoulder, or right lumbar fossa.

• Ultrasound of the biliary tract is the best initial imaging examination for acute cholecystitis and may show wall thickening greater than 3 mm, gallstones, or cystic duct dilatation.

📌 Acute cholecystitis is treated urgently with empirical antibiotics, analgesics, and cholecystectomy immediately for complicated forms, classically within 48 hours, or later after sepsis has resolved; treatment lasts 7 days if not operated on or drained and 1–3 days if operated on.

📌 Acute cholangitis requires urgent antibiotics and analgesics followed by surgical or endoscopic biliary drainage, with the timing determined by severity; antibiotics continue for 3 days after drainage.

Further detail

• In acute cholangitis, blood cultures are positive in 50% of cases and laboratory testing shows inflammatory syndrome, cytolysis, cholestasis, and increased conjugated bilirubin.

💡 Memory Hook

Cholecystitis affects the gallbladder, whereas cholangitis affects the main bile duct

📖 6. Hepatic Abscesses

★ Must-know

📌 Hepatic abscesses are either pyogenic and usually polymicrobial, often of biliary or colonic origin, or amoebic, particularly after travel to a tropical area.

• Hepatic abscesses typically cause fever and right hypochondrial pain radiating to the shoulder and worsened by shaking the liver.

• 🔄 Diagnosis proceeds through: computed tomography or biliary ultrasound, assessment of number, size, and location, image-guided percutaneous aspiration when needed

📌 Treatment combines empirical antibiotics adapted to positive samples, lasting 4–6 weeks, with percutaneous radiological drainage for large abscesses or peritoneal signs; surgery is reserved for complications such as perforation or peritonitis.

Further detail

• The reported bacterial groups include:
  • Gram-negative bacilli such as Escherichia coli and Klebsiella
  • anaerobes
  • Gram-positive cocci

💡 Memory Hook

Pyogenic abscesses are bacterial, whereas amoebic abscesses suggest tropical travel

📖 7. Urgent Diagnostic and Therapeutic Principles

📝 Essential Points

📌 An intra-abdominal infection should be suspected when abdominal pain is associated with fever, and diagnosis relies on appropriate imaging followed by combined medical-surgical management.

💡 Memory Hook

Pain + fever → imaging → medical-surgical treatment

📊 Synthesis Tables

Main Intra-Abdominal Infections

Condition	Typical location or mechanism	Key imaging	Main treatment
Acute appendicitis	Intraluminal obstruction; right iliac fossa	Computed tomography	Emergency surgery and adapted antibiotics
Peritonitis	Peritoneal inflammation; often digestive perforation	Abdominal computed tomography	Surgery, lavage, drainage, and antibiotics
Sigmoid diverticulitis	Infected colonic diverticula; left iliac fossa	Abdominal computed tomography	Antibiotics or symptomatic care; surgery if complicated
Acute cholecystitis	Prolonged cystic duct obstruction	Biliary ultrasound	Antibiotics and cholecystectomy or drainage
Acute cholangitis	Main bile duct obstruction	Biliary ultrasound or biliary MRI	Antibiotics and biliary drainage
Hepatic abscess	Pyogenic or amoebic liver infection	CT or ultrasound	4–6 weeks of antibiotics and possible drainage