Can Retroperitoneal Pain from Diverticulitis Cause Lower Back Pain?
Yes, diverticulitis can cause lower back pain, particularly in elderly patients, but this presentation is atypical and should prompt consideration of alternative diagnoses before assuming diverticulitis is the cause. 1
Understanding the Atypical Presentation
The classic presentation of acute diverticulitis—left lower quadrant abdominal pain, fever, and leukocytosis—occurs in only 50% of patients older than 65 years, with only 17% presenting with fever. 2 This means that elderly patients frequently present with atypical symptoms, including back pain as a primary or prominent feature. 1, 3
When back pain is the primary symptom in a patient with suspected diverticulitis, the American Academy of Family Physicians specifically recommends considering alternative diagnoses such as:
- Renal pathology (kidney stones, pyelonephritis)
- Musculoskeletal issues
- Other retroperitoneal processes 1
Critical Diagnostic Approach
Do not assume diverticulitis based solely on a history of the disease when back pain is the primary symptom. 1 The misdiagnosis rate based on clinical examination alone is 34-68% in elderly patients, making imaging essential. 1
Mandatory Imaging Protocol
Obtain CT abdomen and pelvis with IV contrast immediately in elderly patients presenting with lower back pain and suspected diverticulitis, as this imaging modality has:
- 98-99% sensitivity for diverticulitis
- 99-100% specificity for diverticulitis
- Simultaneous evaluation for renal pathology (more consistent with back pain presentation) 1, 4
For patients who cannot receive IV contrast due to severe kidney disease or contrast allergy, use ultrasound, MRI, or CT without contrast as alternatives. 2
Laboratory Studies
Obtain complete blood count and C-reactive protein, but recognize their limitations:
- 43% of elderly patients with diverticulitis do not have leukocytosis 1
- 39% of patients with complicated diverticulitis have CRP below 175 mg/L 5
Do not exclude diverticulitis based on normal white blood cell count or CRP in elderly patients. 1, 5
Mechanism of Back Pain in Diverticulitis
While the provided guidelines do not explicitly detail the anatomical mechanism, retroperitoneal inflammation from diverticulitis can cause referred pain to the back through:
- Direct retroperitoneal extension of inflammation
- Pericolic abscess formation extending posteriorly
- Irritation of retroperitoneal structures 6
The sigmoid colon lies in close proximity to retroperitoneal structures, and complicated diverticulitis with abscess formation (WSES stage 1b-2a) can extend into the retroperitoneum, causing back pain. 2
Management Based on Imaging Findings
Once diverticulitis is confirmed on CT imaging:
For uncomplicated diverticulitis (WSES stage 0):
- Avoid antibiotics in immunocompetent elderly patients without sepsis-related organ failures 2
- Observation with pain management (acetaminophen) and clear liquid diet 4
For complicated diverticulitis with abscess ≥4 cm (WSES stage 2a):
For diffuse peritonitis (WSES stage 3-4):
- Prompt emergency surgical source control 2
Critical Pitfalls to Avoid
- Never rely on clinical presentation alone in elderly patients—the atypical presentation rate is too high 1, 3
- Never delay imaging in elderly patients with abdominal or back pain and suspected diverticulitis, regardless of normal laboratory values 2
- Never assume recurrent diverticulitis in a patient with a history of the disease when back pain is the primary symptom without confirmatory imaging 1
- Always consider renal pathology as the primary differential diagnosis when back pain predominates 1
Mortality Considerations
In-hospital mortality for acute left colonic diverticulitis increases dramatically with age:
- 1.6% in patients younger than 65 years
- 9.7% in patients 65-79 years
- 17.8% in patients above 80 years 5
This high mortality risk in elderly patients underscores the importance of aggressive diagnostic evaluation and appropriate treatment escalation when indicated.