Can Diverticulitis Cause Left Back Pain?
Yes, patients with diverticulitis can experience left back pain, though it is not the typical presentation—the classic symptom is left lower quadrant abdominal pain that may radiate posteriorly or be perceived as back pain due to retroperitoneal inflammation.
Typical Pain Pattern in Diverticulitis
Left lower quadrant abdominal pain is the hallmark symptom of acute diverticulitis, reflecting the predominant left-sided distribution of diverticula in the sigmoid and descending colon 1, 2.
The pain typically localizes to the left iliac fossa and may be associated with fever, leukocytosis, changes in bowel habit, nausea, and vomiting 1, 2, 3.
Pain duration before presentation averages 14 days (range 1-270 days), and approximately 61% of patients have had a previous documented attack 4.
Atypical Pain Presentations
Patients may present with right-sided or suprapubic pain caused by right-sided diverticulosis or a redundant sigmoid loop lying toward the right side, which can mimic appendicitis 1.
Dysuria and urinary frequency may occur if the inflamed bowel segment is adjacent to the bladder 1.
While not explicitly stated in the guidelines, retroperitoneal inflammation from diverticulitis can cause referred pain to the left flank or back, particularly when there is pericolonic inflammation or abscess formation extending posteriorly.
Diagnostic Approach When Back Pain Is Present
Contrast-enhanced CT of the abdomen and pelvis is the gold standard for diagnosing diverticulitis, with sensitivity and specificity approaching 98-100% 5, 6, 2.
Key CT Findings:
- Pericolonic fat stranding (the defining feature) 6
- Bowel wall thickening 6
- Diverticular abscess (16% of cases) 4
- Free air indicating perforation (10% of cases) 4
- Fistula formation (1% of cases) 4
Critical Imaging Considerations:
- Non-contrast CT has severely limited sensitivity for detecting the inflammatory changes that define diverticulitis 6.
- IV contrast is essential for identifying pericolonic inflammation, abscess formation, and bowel wall thickening 6.
- If contrast CT is refused or contraindicated, MRI abdomen/pelvis with gadolinium is an alternative with 86-94% sensitivity and 88-92% specificity, though it may miss small amounts of extraluminal air 6, 7.
Important Differential Diagnoses
When a patient presents with left-sided abdominal/back pain, consider:
- Pyelonephritis or urolithiasis (both can cause left flank/back pain and may coexist with or mimic diverticulitis) 5
- Lumbar radiculopathy (can cause left back pain radiating down the leg, unrelated to diverticulitis) 8
- Epiploic appendagitis (can mimic diverticulitis with left lower quadrant pain) 9
- Colonic malignancy (5-7% of patients undergoing surgery for presumed diverticulitis have unsuspected carcinoma) 4
Red Flags Requiring Immediate Evaluation
The following symptoms mandate emergency assessment regardless of imaging 6, 7:
- Fever with systemic signs of sepsis
- Inability to pass gas or stool
- Severe tenderness with guarding or peritoneal signs
- Persistent vomiting
- Bloody stools
- Signs of shock or hemodynamic instability
Common Diagnostic Pitfalls
- Never attribute pain to incidental diverticulosis alone—this is one of the most common diagnostic errors in evaluating left-sided abdominal pain 6.
- The classic triad of left lower quadrant pain, fever, and leukocytosis is present in only 25% of diverticulitis cases, making clinical diagnosis alone unreliable 5.
- Misdiagnosis based on clinical assessment alone occurs in 34-68% of cases, emphasizing the need for imaging confirmation 5.
Management Implications
Uncomplicated diverticulitis (85% of cases) can be managed with observation, pain control (typically acetaminophen), and dietary modification with a clear liquid diet 2.
Antibiotics should be reserved for specific high-risk situations: persistent fever/chills, increasing leukocytosis, age >80 years, pregnancy, immunocompromise, or chronic medical conditions like cirrhosis or poorly controlled diabetes 2.
Complicated diverticulitis (abscess, perforation, fistula, obstruction) requires IV antibiotics (ceftriaxone plus metronidazole or piperacillin-tazobactam) and may require percutaneous drainage or surgical resection 2, 4.