Intra-Abdominal Infections

Definition

Intra-abdominal infections (IAIs) in children are infections occurring within the peritoneal cavity or retroperitoneal space, often resulting from gastrointestinal perforation, appendicitis, or secondary spread from other abdominal organs, leading to localized or diffuse peritonitis.

Epidemiology

• Common cause of pediatric hospitalization for surgical and medical management
• Highest incidence in children under 5 years due to appendicitis and neonatal necrotizing enterocolitis
• Males slightly more affected than females in appendicitis-related IAIs
• Postoperative and trauma-related IAIs occur in older children
• Increasing incidence of multidrug-resistant organisms in hospital-acquired IAIs

Etiology

• Appendicitis with perforation (most common in older children)
• Necrotizing enterocolitis in neonates and preterm infants
• Perforated bowel due to trauma, obstruction, or foreign body
• Primary peritonitis: Streptococcus pneumoniae, E. coli, or Klebsiella species
• Secondary peritonitis from perforated viscus (e.g., duodenal ulcer, diverticulitis rare in children)
• Postoperative or post-traumatic infections
• Immunocompromised children may develop fungal IAIs

Pathophysiology

• Bacterial invasion of the peritoneal cavity triggers local inflammation
• Release of cytokines leads to systemic inflammatory response
• Peritoneal exudate formation and adhesion development
• Spread of infection can cause generalized peritonitis or abscess formation
• Impaired gut barrier function in neonates predisposes to translocation of bacteria
• Sepsis may occur if infection is uncontrolled or delayed in treatment
• Organ dysfunction can result from systemic inflammation and hypotension