Is lower back left pain a symptom of acute diverticulitis flares, especially in older adults with a history of diverticulitis?

Lower Back Left Pain and Acute Diverticulitis

Lower back left pain is NOT a typical presenting symptom of acute diverticulitis, which classically presents with left lower quadrant abdominal pain, not back pain. While pain can occasionally radiate, back pain as a primary symptom should prompt consideration of alternative diagnoses such as renal pathology, musculoskeletal issues, or retroperitoneal processes.

Classic Presentation of Acute Diverticulitis

The typical clinical triad consists of 1:

• Left lower quadrant abdominal pain (not back pain)
• Fever
• Leukocytosis

However, this classic presentation is significantly less common in elderly patients 1:

• Only 50% of patients older than 65 years present with pain in the lower quadrants of the abdomen
• Only 17% have fever
• 43% do not have leukocytosis

Why Back Pain Should Raise Concern

Left lower back pain as a primary symptom is atypical for diverticulitis and warrants investigation for other causes 1. The differential diagnosis for left lower-quadrant and back pain includes 1:

• Renal/ureteric pathology (pyelonephritis, urolithiasis, renal abscess)
• Musculoskeletal causes
• Retroperitoneal processes
• Gastrointestinal pathology (including but not limited to diverticulitis)

Diagnostic Approach When Back Pain is Present

Do not rely on clinical symptoms alone, especially in elderly patients, as clinical diagnosis has only 68% sensitivity 1. The atypical presentation in older adults makes imaging essential 1.

Imaging Recommendations:

• CT abdomen and pelvis with IV contrast is the preferred diagnostic test with 98-99% sensitivity and 99-100% specificity for diverticulitis 2, 3
• This imaging will simultaneously evaluate for renal pathology, which is more consistent with back pain 1
• In elderly patients with suspected diverticulitis, CT should be obtained in essentially all cases given the high rate of atypical presentations 1

Laboratory Studies:

• Complete blood count (looking for leukocytosis, though absent in 43% of elderly patients with diverticulitis) 1
• C-reactive protein (CRP >170-175 mg/L suggests complicated disease, though 39% of complicated cases have lower levels) 1
• Urinalysis to evaluate for urinary tract infection or kidney stones, which are more consistent with back pain 4

Critical Pitfalls to Avoid

Do not assume diverticulitis based on a history of the disease when back pain is the primary symptom 1. The location of pain matters significantly in diagnosis 1, 3.

Do not skip imaging in elderly patients even with known diverticulitis history, as 1:

• Clinical presentation is unreliable in this population
• Misdiagnosis rates are 34-68% based on clinical examination alone
• Complications are more common and mortality is significantly higher (9.7% in ages 65-79,17.8% in ages >80) 1, 2

Consider that pain radiating to the back could indicate 2:

• Complicated diverticulitis with abscess formation
• Retroperitoneal extension of inflammation
• Alternative diagnosis entirely

When to Suspect Diverticulitis Despite Atypical Presentation

Proceed with CT imaging if 1, 3:

• Patient has known diverticulosis or prior diverticulitis
• Any left-sided abdominal tenderness is present (even if back pain predominates)
• Systemic symptoms present (fever, malaise, nausea)
• Elevated inflammatory markers (CRP, leukocytosis)

The key message: back pain is not a characteristic symptom of diverticulitis, and its presence as the primary complaint should broaden your differential diagnosis beyond diverticulitis alone 1, 4.