What are the signs and symptoms of diverticulitis, including warning signs of complications?

Diverticulitis Signs and Symptoms

The most common presenting sign of acute diverticulitis is left lower quadrant abdominal pain (present in 67-100% of cases), typically accompanied by fever, nausea, and leukocytosis. 1, 2

Primary Clinical Presentation

Cardinal Symptoms

• Abdominal pain: Acute or subacute onset, predominantly in the left lower quadrant (67% of cases), though right lower quadrant pain occurs in 24% of younger patients 3
• Fever: Present in 71% of cases, with mean temperature around 100.7°F 3
• Nausea: Occurs in 86% of patients, typically without vomiting 1
• Change in bowel habits: Constipation or diarrhea 4
• Dysuria: May occur due to bladder irritation 5

Physical Examination Findings

• Left lower quadrant tenderness: Most consistent finding
• Tachycardia: Mean pulse rate of 103 bpm 3
• Abdominal distention 5

Laboratory Abnormalities

• Leukocytosis: Present in 90% of cases 3
• Elevated C-reactive protein (CRP) 1

Critical Warning Signs of Complicated Diverticulitis

Only 12% of patients present with complicated disease, but recognizing these features is essential to prevent mortality. 1

Red Flags Requiring Immediate Imaging and Surgical Consultation

• Signs of peritonitis: Diffuse abdominal tenderness, guarding, rebound
• Signs of perforation: Free air on imaging, acute deterioration
• Obstruction: Inability to pass stool or flatus, severe distention
• Severe sepsis: Hypotension, altered mental status, organ dysfunction
• Symptom duration >5 days before presentation (predictor of progression to complicated disease) 6

Complications to Recognize

The most common complications in order of frequency are 1:

1. Abscess or phlegmon
2. Peritonitis (from perforation)
3. Obstruction
4. Stricture
5. Fistula (bladder, vagina, or rarely retroperitoneal with thigh extension) 7

Important Clinical Caveats

Age-Related Presentation Differences

In elderly patients (>65 years), the presentation is often atypical and more subtle 2:

• Only 50% present with lower quadrant pain
• Only 17% have fever
• 43% lack leukocytosis
• Higher proportion present with diverticular bleeding instead

This atypical presentation in the elderly can delay diagnosis and increase mortality risk.

Diagnostic Accuracy Without Imaging

Clinical suspicion alone is correct in only 40-65% of cases 1. This underscores why CT imaging is essential for first presentations and severe cases—diverticulitis can be mimicked by appendicitis, colon cancer, inflammatory bowel disease, gynecologic conditions, and renal pathology 6.

When Imaging is Mandatory

CT abdomen/pelvis with IV contrast should be obtained for 1, 6:

• First episode without prior imaging-confirmed diagnosis
• Severe presentations with signs of complications
• Failure to improve with initial therapy
• Immunocompromised patients
• Multiple recurrences when considering surgery

Distinguishing from Colon Cancer

Perforated colon cancer can mimic diverticulitis. CT findings suggesting cancer rather than diverticulitis include pericolonic lymphadenopathy >1 cm in short axis 8. When inflammatory changes and edema in the sigmoid mesentery are present without pericolonic lymphadenopathy, diverticulitis is most likely 8.

Practical Clinical Algorithm

For a patient presenting with left lower quadrant pain:

1. Assess for typical triad: LLQ pain + fever + leukocytosis
2. Evaluate for complications: Check for peritonitis, sepsis, obstruction
3. Consider atypical presentations: Especially in elderly (may lack classic findings) or young patients (may have RLQ pain mimicking appendicitis)
4. Obtain CT imaging if: first episode, severe symptoms, immunocompromised, or diagnostic uncertainty
5. Recognize that plain radiographs are normal in 79% of cases and should not be relied upon for diagnosis 3