What is the diagnostic approach and management for a patient presenting with intestinal spasm, considering potential underlying conditions such as Irritable Bowel Syndrome (IBS), Inflammatory Bowel Disease (IBD), infections, or mechanical obstruction?

Diagnostic Approach for Intestinal Spasm

Make a positive clinical diagnosis of irritable bowel syndrome (IBS) based on symptom criteria without extensive testing in patients under 45 years without alarm features. 1

Initial Clinical Assessment

Symptom Criteria for Diagnosis

• Abdominal pain or discomfort present for at least 12 weeks (not necessarily consecutive) in the past 12 months, with two of three features: 1
  • Pain relieved by defecation
  • Associated with change in stool frequency
  • Associated with change in stool consistency
• Supportive symptoms include bloating, passage of mucus, sensation of incomplete evacuation, and straining 1
• Symptoms typically triggered by stress, intercurrent illness, drugs, or eating 1

Critical Red Flags Requiring Investigation

Do not diagnose IBS if any of these alarm features are present: 1

• Age >50 years with new-onset symptoms
• Unintentional weight loss
• Rectal bleeding or blood in stool
• Nocturnal diarrhea or abdominal pain
• Family history of colorectal cancer or inflammatory bowel disease
• Fever or systemic symptoms
• Anemia on blood testing

Behavioral Features Supporting IBS Diagnosis

• Symptoms present for more than 6 months 1
• Frequent consultations for non-gastrointestinal symptoms 1
• Patient reports stress aggravates symptoms 1
• Previous medically unexplained symptoms 1

Laboratory Testing Strategy

Minimal Testing for Typical IBS (Age <45, No Alarm Features)

Obtain only: 1, 2

• Complete blood count (CBC) to exclude anemia
• C-reactive protein (CRP) or ESR to exclude inflammation
• Celiac serology (IgA tissue transglutaminase with total IgA) 2
• Fecal calprotectin if available (values <50 μg/g effectively exclude IBD) 2

Additional Testing for Atypical Features

For diarrhea-predominant symptoms with atypical features (nocturnal diarrhea, prior cholecystectomy): 1

• Consider bile acid diarrhea testing (SeHCAT scanning or serum 7α-hydroxy-4-cholesten-3-one)
• Colonoscopy with biopsies to exclude microscopic colitis, especially if: 1
  • Female sex
  • Age ≥50 years
  • Coexistent autoimmune disease
  • Severe watery diarrhea
  • Duration <12 months
  • Weight loss
  • Use of NSAIDs, PPIs, SSRIs, or statins

For constipation-predominant symptoms with features of obstructive defecation: 1

• Consider anorectal physiology testing to identify dyssynergic defecation

Tests NOT Indicated in Typical IBS

Do not perform: 1

• Routine colonoscopy (yield is extremely low and provides no reassurance benefit)
• Hydrogen breath testing for small intestinal bacterial overgrowth
• Testing for exocrine pancreatic insufficiency
• Carbohydrate intolerance testing in absence of specific dietary triggers

Distinguishing IBS from Inflammatory Bowel Disease

Key Clinical Distinctions

IBS characteristics: 1, 2

• Pain relieved with defecation
• No systemic symptoms (fever, malaise, anorexia)
• Normal inflammatory markers
• Fecal calprotectin <50 μg/g
• Symptoms fluctuate and are triggered by stress or eating

IBD characteristics requiring full workup: 2, 3

• Systemic symptoms (fever, malaise, anorexia, weight loss)
• Nocturnal symptoms
• Bloody diarrhea with urgency
• Elevated inflammatory markers (CRP, ESR)
• Fecal calprotectin >200-250 μg/g
• Anemia or hypoalbuminemia

Management After Diagnosis

Communication and Education

Explain IBS as a disorder of gut-brain interaction with visceral hypersensitivity as the primary mechanism. 1 Emphasize that IBS is chronic with fluctuating symptoms but does not increase cancer risk or mortality, though it significantly affects quality of life 1.

First-Line Pharmacologic Treatment for Spasm

FDA-approved antispasmodics for functional bowel/irritable bowel syndrome: 4, 5

• Dicyclomine (anticholinergic antispasmodic) 4
• Hyoscyamine (anticholinergic for visceral spasm and hypermotility in spastic colitis) 5

Additional Treatment Considerations

• Low FODMAP diet shows evidence of benefit 1
• Psychological therapies (cognitive behavioral therapy, hypnotherapy) are effective for abdominal symptoms 1
• Tricyclic antidepressants or SSRIs for pain management in refractory cases 1
• Loperamide for diarrhea-predominant symptoms 1
• PEG or secretagogues for constipation-predominant symptoms 1

Common Pitfalls to Avoid

Do not over-investigate patients with typical IBS symptoms and no alarm features - this increases costs without improving outcomes and does not provide reassurance 1. The yield of colonoscopy in typical IBS is extremely low 1.

Do not dismiss the diagnosis if the patient has psychological comorbidity - anxiety and depression are common in IBS but do not exclude the diagnosis 1, 6.

Recognize that up to 80% of IBS patients report at least one alarm symptom - the presence of a single alarm feature has modest diagnostic performance and should be interpreted in clinical context 1.