What is Microperforation in Diverticulitis?
Microperforation in diverticulitis refers to a small, contained perforation of an inflamed diverticulum that results in localized pericolic inflammation with or without small amounts of extraluminal air, but without frank peritonitis or large abscess formation. This represents a form of complicated diverticulitis that falls on the spectrum between uncomplicated disease and free perforation with generalized peritonitis 1.
Clinical and Radiologic Characteristics
Microperforation manifests on CT imaging as:
- Pericolic extraluminal air (small gas bubbles adjacent to the inflamed colon)
- Localized fat stranding in the pericolic region
- Small fluid collections without organized abscess formation
- Absence of distant free air or diffuse peritoneal fluid 1, 2
The key distinguishing feature is that the perforation is contained by surrounding tissues and mesentery, preventing widespread peritoneal contamination 3. This differs from free perforation where air and enteric contents spread throughout the peritoneal cavity.
Pathophysiology
Two mechanisms explain microperforation:
In elderly patients with multiple diverticula: Fecalith impaction causes mucosal damage, bacterial proliferation, and eventual small perforation through the diverticulum wall 3
In younger patients with fewer diverticula: Forceful muscular contractions occlude blood vessels supplying the colonic wall, leading to ischemic damage and subsequent microperforation 3
Clinical Management Implications
Highly selected hemodynamically stable patients with microperforation can be managed conservatively without immediate surgery 1. The 2017 WSES guidelines specifically state that patients with perforated diverticulitis including small abscesses (<4 cm) can be managed without definitive source control if responding to antimicrobial therapy (Recommendation 1B) 1.
Conservative Management Criteria:
- Hemodynamic stability (normal blood pressure, no signs of shock)
- Pericolic air only or minimal distant intraperitoneal air on CT
- No clinical diffuse peritonitis (no rigid abdomen, no rebound tenderness throughout)
- No fluid in the pouch of Douglas 1, 2
When Conservative Management Fails:
Non-operative treatment has a 57-60% failure rate when there is 1, 2:
- Large amounts of distant intraperitoneal air
- Distant retroperitoneal air
- Clinical signs of generalized peritonitis
Critical monitoring is mandatory - patients require close clinical observation and repeat imaging if symptoms worsen, as failure of conservative management necessitates urgent surgical intervention 2.
Common Pitfalls
Assuming all extraluminal air requires surgery: Small amounts of pericolic air can be managed conservatively in stable patients 1, 2
Failing to distinguish microperforation from free perforation: The presence of any free air does not automatically mandate surgery - the amount and location of air, combined with clinical status, determines management 1
Inadequate monitoring: Even with appropriate initial conservative management, approximately 25% of hospitalized diverticulitis patients may ultimately require surgery 2
Delayed recognition of treatment failure: Time between diagnosis and surgery predicts mortality when surgery becomes necessary (P=0.04) 1 - don't persist with failing conservative management
The 2023 ACR guidelines emphasize that medical therapy is indicated for locally perforated diverticulitis without a drainable collection, while surgery is reserved for free perforation with peritonitis 4. This represents the modern evidence-based approach to microperforation management.