What does a CT scan showing segmental thickening and enhancement of the colonic wall with air-filled pouches in the surrounding segments indicate?

Diagnosis: Acute Colonic Diverticulitis

The CT findings of segmental colonic wall thickening and enhancement with air-filled pouches (diverticula) in the surrounding segments are diagnostic of acute diverticulitis, most likely representing uncomplicated or localized complicated disease depending on the extent of extraluminal air. 1

Key CT Findings Present

Your patient's scan demonstrates the classic radiological triad of acute diverticulitis:

• Segmental colonic wall thickening (>5 mm) - represents inflammation of the affected bowel segment 2, 3
• Colonic wall enhancement - indicates active inflammatory process with increased vascularity 2
• Air-filled pouches (diverticula) - the underlying anatomical substrate for the disease 2

The pericolonic fat stranding that typically accompanies these findings represents inflammatory changes in the surrounding adipose tissue 2, 3

Disease Severity Classification

The presence and location of extraluminal air is critical for determining disease severity and treatment approach:

• Small-volume pericolic air (<5 cm from affected segment) = WSES Stage 1a (localized complicated diverticulitis without abscess) - can be managed medically with antibiotics 1
• Distant extraluminal air (>5 cm) or free intraperitoneal air = suggests perforation requiring surgical evaluation 1
• Absence of extraluminal air = likely uncomplicated diverticulitis (WSES Stage 0) 1

Clinical Implications and Next Steps

CT has 98% sensitivity and up to 99% specificity for diagnosing acute diverticulitis, making it the gold standard imaging modality. 1, 4

Assess for Complications

Look specifically for these CT findings that would change management:

• Abscess formation - rim-enhancing fluid collection requiring drainage if ≥3 cm 1, 2
• Free perforation - free intraperitoneal air with peritonitis requiring emergency surgery 1
• Fistula or stricture - typically requires surgical management 1
• Extent of colonic involvement - longer segments predict higher recurrence and treatment failure 1

Risk Stratification

CT findings predict clinical outcomes: 5

• Colonic wall thickness <9 mm = 19% recurrence risk 2
• Severe CT findings (perforation signs) = 49% rate of remote complications at 5 years 5
• Moderate CT findings = 22% rate of remote complications at 5 years 5

Treatment Algorithm Based on CT Findings

For uncomplicated diverticulitis (no abscess, perforation, or distant air):

• Immunocompetent patients without sepsis may not require antibiotics 1
• Can consider outpatient management in carefully selected patients 4

For localized complicated diverticulitis with pericolic air (WSES Stage 1a):

• Antibiotic therapy is recommended 1
• Hospitalization with IV antibiotics for significant findings 3

For abscess ≥3 cm:

• CT-guided percutaneous drainage plus antibiotics 1

For free perforation or peritonitis:

• Emergency surgical intervention required 1, 4

Important Caveats

• Elevated CRP >173 mg/L indicates more severe disease and predicts need for intervention 1, 3
• Immunocompromised patients are at higher risk for treatment failure and require more aggressive management with lower threshold for surgery 1, 3
• Follow-up colonoscopy should be performed 6 weeks after complicated diverticulitis or if presentation is atypical to exclude colorectal cancer 4
• Location of diseased segment varies in 35% of patients between episodes, so repeat imaging before elective surgery is important 5