What is the appropriate treatment and classification for an adult patient with complicated diverticulitis, likely having significant comorbidities or immunosuppression, using the Hinchey classification?

Hinchey Classification of Diverticulitis

The Hinchey classification remains the most widely used system for categorizing acute diverticulitis severity, with the Modified Hinchey Classification incorporating CT findings to guide treatment decisions ranging from conservative management to emergent surgery. 1

Classification Systems Overview

Multiple classification systems exist for acute left-sided colonic diverticulitis, though none has been conclusively proven superior in predicting patient outcomes. 1 However, the Hinchey classification has dominated international literature for three decades and provides the framework most clinicians use. 1

Original Hinchey Classification (Surgical Findings)

The original system categorizes severity into four stages based on operative findings: 1

• Hinchey I: Pericolic abscess
• Hinchey II: Pelvic, intra-abdominal, or retroperitoneal abscess
• Hinchey III: Generalized purulent peritonitis
• Hinchey IV: Fecal peritonitis

Modified Hinchey Classification (CT-Based)

The 2005 Kaiser modification incorporated CT findings for more precise preoperative diagnosis: 1, 2

• Stage 0: Mild clinical diverticulitis
• Stage 1a: Confined pericolic inflammation
• Stage 1b: Confined pericolic abscess
• Stage 2: Pelvic or distant intra-abdominal abscess
• Stage 3: Generalized purulent peritonitis
• Stage 4: Fecal peritonitis at presentation

Alternative Classification: Mora Lopez (Neff Modification)

This system provides more granular staging for early complicated disease: 1, 3

1. Uncomplicated: Diverticula, wall thickening, increased pericolic fat density
2. Locally complicated:
   • 2a: Localized pneumoperitoneum (gas bubbles)
   • 2b: Abscess < 4 cm
3. Complicated with pelvic abscess: Abscess > 4 cm in pelvis
4. Complicated with distant abscess: Abscess in abdominal cavity outside pelvis
5. Complicated with distant complications: Abundant pneumoperitoneum and/or free intra-abdominal fluid

WSES CT-Guided Classification

The World Society of Emergency Surgery proposed a simplified two-tier system: 1, 4

Uncomplicated: Infection confined to colon without peritoneal extension 1

Complicated (4 stages based on infectious process extension): 1, 4

• Stage 1A: Pericolic air bubbles or small pericolic fluid without abscess (within 5 cm)
• Stage 1B: Abscess ≤ 5 cm
• Stage 2: Abscess > 5 cm or distant from colon
• Stage 3: Diffuse fluid without distant free gas
• Stage 4: Diffuse fluid with distant free gas

Treatment Algorithm Based on Classification

CT Imaging is Mandatory

CT scan with contrast is essential for accurate classification and must not be omitted, as clinical examination alone has poor diagnostic accuracy. 2, 3, 4 CT has 98-99% sensitivity and 99-100% specificity for diagnosing acute diverticulitis. 5

Stage-Specific Management

Uncomplicated Diverticulitis (Hinchey 0, Stage 1a):

• Observation with pain management (acetaminophen preferred) 5
• Clear liquid diet 5
• Reserve antibiotics for: persistent fever/chills, increasing leukocytosis, age > 80 years, pregnancy, immunocompromised status (chemotherapy, high-dose steroids, transplant recipients), or chronic conditions (cirrhosis, chronic kidney disease, heart failure, poorly controlled diabetes) 5
• First-line oral antibiotics: amoxicillin/clavulanic acid OR cefalexin plus metronidazole 5

Small Abscess (Hinchey 1b, < 4 cm):

• Non-operative management with bowel rest and antibiotics 2, 3, 4
• Intravenous antibiotics if unable to tolerate oral intake: cefuroxime or ceftriaxone plus metronidazole, OR ampicillin/sulbactam 5

Larger Abscess (Hinchey 2, ≥ 4 cm):

• Percutaneous drainage is recommended 2, 3, 4
• Intravenous antibiotics: ceftriaxone plus metronidazole OR piperacillin-tazobactam 5

Generalized Purulent Peritonitis (Hinchey 3):

• Surgical intervention required 4
• Intravenous broad-spectrum antibiotics 5
• Primary resection with anastomosis in selected patients with favorable physiology 6
• Hartmann's procedure remains gold standard for higher ASA scores 6

Fecal Peritonitis (Hinchey 4):

• Emergent laparotomy with colonic resection 5
• Hartmann's procedure typically preferred given severity 6
• Postoperative mortality: 10.6% for emergent resection vs 0.5% for elective 5

Critical Pitfalls to Avoid

Do not rely on clinical examination alone - CT imaging is mandatory for accurate staging and appropriate treatment selection. 2, 3, 4

Do not routinely prescribe antibiotics for uncomplicated diverticulitis - Reserve for patients with specific risk factors (systemic symptoms, immunocompromise, advanced age, pregnancy, chronic comorbidities). 5

Do not delay surgical consultation for Hinchey 3-4 - Generalized peritonitis requires emergent operative management, and delays increase mortality. 5, 6

Consider patient physiologic status and comorbidities when selecting between primary anastomosis versus Hartmann's procedure for perforated diverticulitis - ASA score and organ dysfunction significantly impact outcomes. 6