What is the best treatment approach for an 80-year-old patient with left lower quadrant abdominal pain, reduced appetite, and a history of diverticulosis, who has multiple bilateral renal cortical cysts, atherosclerotic calcification, and degenerative changes in the lumbar spine, as shown on a recent CT scan?

Management of Suspected Uncomplicated Diverticulitis in an Elderly Patient

Given this patient's age (80s), left lower quadrant pain, reduced appetite, and CT findings showing only diverticulosis without signs of acute inflammation (no bowel wall thickening, pericolonic fat stranding, abscess, or perforation), this appears to be chronic diverticulosis rather than acute diverticulitis, and conservative management without antibiotics is appropriate while addressing the constipation. 1

Critical Diagnostic Limitation

The CT scan performed was non-contrast, which severely compromises diagnostic accuracy for diverticulitis:

• Non-contrast CT has limited sensitivity for detecting the inflammatory changes that define diverticulitis (pericolonic fat stranding, bowel wall thickening >5mm, abscess formation) 2
• The American College of Radiology states that contrast enhancement is essential for identifying pericolonic inflammation and bowel wall thickening, with sensitivity/specificity approaching 98-100% when properly performed 1, 2
• The most common diagnostic error is attributing pain to incidental diverticulosis when no inflammatory process is demonstrated 2

What the CT Actually Shows

The imaging findings suggest chronic diverticulosis, not acute diverticulitis:

• Multiple colonic diverticula throughout the colon (anatomic finding, not inflammatory) 1
• Large bowel distension with increased fecal material (suggesting constipation/fecal impaction) 1
• No mention of bowel wall thickening, pericolonic fat stranding, or abscess - the hallmarks of acute diverticulitis 1
• Stable findings compared to previous scan 1

Immediate Management Approach

Step 1: Assess for Red Flags Requiring Urgent Evaluation

Check for signs of complicated diverticulitis that would mandate immediate intervention regardless of imaging 2, 3:

• Fever or elevated temperature 1
• Peritoneal signs (guarding, rebound tenderness, rigidity) 1, 3
• Inability to pass gas or stool (complete obstruction) 2
• Vomiting 2
• Bloody stools 2
• Leukocytosis with left shift >75% 1
• Elevated inflammatory markers (CRP, procalcitonin) 1, 4

Step 2: Address the Constipation

The CT shows large bowel distension with increased fecal material, which is likely the primary cause of symptoms:

• Initiate bowel regimen with osmotic laxatives (polyethylene glycol) and stimulant laxatives if needed 1
• Ensure adequate hydration 1
• Consider gentle enema if severe impaction 1
• Increase dietary fiber once acute symptoms resolve 1

Step 3: Consider Repeat Imaging with Contrast

If symptoms persist or worsen despite conservative management, obtain CT abdomen/pelvis WITH IV contrast to definitively exclude acute diverticulitis 1, 2:

• This is critical because non-contrast CT cannot reliably diagnose or exclude diverticulitis 2
• If contrast CT is contraindicated, MRI abdomen/pelvis with gadolinium has 86-94% sensitivity for inflammatory conditions 2
• Check inflammatory markers (CBC, CRP) to assess for occult inflammation not visible on non-contrast imaging 2

When Antibiotics Are NOT Indicated

Conservative treatment without antibiotics is recommended for 1:

• Uncomplicated acute diverticulitis in immunocompetent patients (WSES stage 0) 1
• Asymptomatic diverticulosis (which this patient may have) 1, 5

When Antibiotics ARE Indicated

Antibiotic therapy for no more than 7 days is recommended for 1:

• CT-confirmed uncomplicated acute diverticulitis in immunocompromised or aged patients 1
• Small diverticular abscesses (antibiotic therapy alone for 7 days) 1

If antibiotics are needed based on contrast CT findings, appropriate regimens for elderly patients include 1, 4:

• Ciprofloxacin 400mg IV q12h plus metronidazole for uncomplicated cases 4
• Ertapenem 1g q24h for patients at high risk of ESBL-producing organisms 1, 4
• Duration: 4 days in immunocompetent, non-critically ill patients with adequate source control; up to 7 days in immunocompromised or critically ill patients 1, 4

Common Pitfalls to Avoid

• Do not diagnose acute diverticulitis based on non-contrast CT showing only diverticulosis - this is the most common diagnostic error 2
• Do not assume left lower quadrant pain in elderly patients with known diverticulosis equals diverticulitis - only 50% present with typical lower quadrant pain 3
• Do not overlook alternative diagnoses including colon cancer (which can present similarly), especially given the patient's age and need for colonoscopy follow-up 1, 3

Follow-Up Considerations

Colonoscopy should be planned after symptom resolution 1:

• The 2022 WSES guidelines suggest early colonic evaluation in elderly patients after an episode of suspected acute left colonic diverticulitis 1
• This is particularly important to exclude colon cancer, which can mimic diverticulitis 3

Elective sigmoid resection is generally NOT recommended unless 1:

• Stenosis, fistulae, or recurrent diverticular bleeding develops 1
• Very symptomatic disease compromising quality of life 1
• Immunocompromised status (if fit for surgery) 1