Differential Diagnoses and Treatment for Chronic Left-Sided Colonic Spasm Pain
Most Likely Diagnosis: Irritable Bowel Syndrome (IBS)
Given the 2-year history of near-constant left-sided spasm pain with observed sigmoid and descending colon spasms on colonoscopy, normal structural imaging, and young age, this presentation is most consistent with IBS, specifically IBS with abnormal colonic motility patterns. 1, 2
Key Diagnostic Considerations
Why IBS is Most Likely
- Female sex and age <45 years significantly increase the likelihood of IBS 1
- The 2-year symptom duration with spasm pattern is characteristic of functional bowel disorders 1
- Observed sigmoid and descending colon spasms during colonoscopy directly correlate with IBS pathophysiology—research demonstrates that IBS patients exhibit exaggerated motility of the descending colon with higher frequency of segmenting pressure waves in the sigmoid colon compared to healthy controls 3, 4
- When structural pathology has been excluded by CT and colonoscopy, functional bowel disorders become the most likely diagnosis 2
Critical Red Flags to Exclude
Before confirming IBS, you must actively exclude:
- Microscopic colitis—requires colonoscopy with biopsies from both right and left colon, as macroscopic appearance is normal but histology shows inflammation 1
- Celiac disease—mandatory testing with tissue transglutaminase IgA antibodies and total IgA level in all patients with chronic abdominal symptoms 1
- Inflammatory bowel disease (early/mild)—test fecal calprotectin to definitively exclude IBD in patients under 45 with chronic symptoms 1
- Bile acid diarrhea—consider if diarrheal phases occur; diagnose with SeHCAT scanning or serum 7α-hydroxy-4-cholesten-3-one testing 1
Additional Differential Diagnoses (Less Likely but Consider)
Gynecologic Causes
- Cyclical pain in premenopausal women suggests gynecologic etiology requiring pelvic/transvaginal ultrasound 2
- Endometriosis can cause left-sided pain and should be evaluated with pelvic ultrasound if not already performed 2
Chronic/Atypical Diverticulitis
- Early or atypical diverticulitis is possible, though CT has 98-100% sensitivity 2, 5
- However, the 2-year constant nature and lack of acute inflammatory episodes makes this less likely 6, 5
Sigmoid Volvulus (Intermittent)
- Can present with recurrent left-sided pain and spasms, though typically causes acute obstruction 7
- Less likely given normal imaging and ability to pass stool/gas 7
Mandatory Diagnostic Workup
Laboratory Testing
- Celiac serology (tissue transglutaminase IgA with total IgA level)—mandatory in all patients with chronic abdominal symptoms 1
- Fecal calprotectin—should be tested to exclude inflammatory bowel disease in patients under 45 with chronic symptoms 1
- Complete blood count—to assess for anemia suggesting occult bleeding or malignancy 1
Endoscopic Evaluation
- If colonoscopy biopsies were not obtained during initial procedure, repeat colonoscopy with biopsies from right and left colon is indicated to exclude microscopic colitis 1
- Biopsies are essential because microscopic colitis appears macroscopically normal but shows histologic inflammation 1
Imaging Considerations
- MRI abdomen and pelvis may be considered if CT was not performed or was equivocal, with sensitivity of 86-94% and specificity of 88-92% for inflammatory conditions 2
- Pelvic/transvaginal ultrasound if gynecologic causes not yet excluded 2
Treatment Approach
First-Line Management for IBS
Patient Education
- Education about the gut-brain axis and how diet, stress, and emotional responses impact symptoms is essential 1
- Set realistic expectations that IBS is chronic with no cure, and treatments aim to improve quality of life 1
Dietary Modifications
- Low FODMAP diet trial—this is evidence-based for IBS symptom reduction 1
- Identify and avoid trigger foods, particularly those that exacerbate pain with food intake 1
Pharmacologic Management
- Antispasmodics (hyoscyamine, dicyclomine)—directly target colonic spasms observed during colonoscopy 8
- Tricyclic antidepressants (low-dose amitriptyline 10-25mg)—modulate visceral pain perception and reduce colonic motility 1
- SSRIs—if anxiety or depression is present, as psychological factors are crucial in IBS 1
Psychological Interventions
- Address anxiety, depression, and stress management needs—these are crucial components of IBS treatment 1
- Consider cognitive behavioral therapy or gut-directed hypnotherapy 1
Specialist Referral Indications
- Gastroenterology referral for functional bowel disorder management if symptoms persist despite conservative measures 2
- Gynecology referral if pelvic ultrasound reveals pathology or high clinical suspicion remains 2
When to Reassess or Escalate
Alarm Features Requiring Urgent Evaluation
- Fever, inability to pass gas/stool, severe tenderness with guarding, vomiting, bloody stools, or signs of shock mandate immediate emergency evaluation 2
- Weight loss, anemia, or change in bowel habits warrant repeat colonoscopy despite prior normal study 2
- New pericolonic lymphadenopathy >1 cm on repeat imaging suggests malignancy rather than benign causes 2
Follow-up Strategy
- If symptoms persist after 6-8 weeks of conservative management, consider bile acid diarrhea testing and gastroenterology referral 1
- Repeat colonoscopy is generally not indicated unless new symptoms develop or significant time has passed 2
Common Pitfalls to Avoid
- Do not assume IBS without excluding microscopic colitis—biopsies are mandatory as the colon appears normal macroscopically 1
- Do not skip celiac serology—it is mandatory in all chronic abdominal pain cases 1
- Do not overlook gynecologic causes in women of reproductive age—pelvic ultrasound is essential if not performed 2
- Do not dismiss the observed spasms as insignificant—they represent objective evidence of abnormal colonic motility patterns characteristic of IBS 3, 4