What is the diagnosis for pain during bowel movements?

Differential Diagnosis for Pain with Bowel Movements

Pain with bowel movements most commonly suggests irritable bowel syndrome (IBS) when the pain is relieved by defecation or associated with changes in stool frequency or consistency, though you must systematically exclude structural causes including inflammatory bowel disease, anorectal pathology, and colorectal cancer based on alarm features. 1

Primary Diagnostic Considerations

Irritable Bowel Syndrome (Most Common)

• IBS is the leading diagnosis when abdominal pain is clearly linked to bowel function—either relieved by defecation or associated with changes in stool frequency or consistency. 1
• The Rome III criteria require recurrent abdominal pain or discomfort at least 3 days per month for the past 3 months, with symptom onset at least 6 months before diagnosis. 1
• Pain that improves with defecation strongly suggests a colonic origin and is one of the original Manning criteria for IBS. 1
• IBS is considered a painful condition; patients with painless bowel dysfunction are labeled as having "functional constipation" or "functional diarrhea" instead. 1

Inflammatory Bowel Disease

• Pain during active inflammation is expected in IBD, but chronic pain can persist even when intestinal inflammation is quiescent due to sensitization of sensory pathways. 1, 2
• Abdominal pain is considered chronic if it has persisted 3-6 months past resolution of the acute insult. 1
• Patients may exhibit allodynia (innocuous stimuli perceived as painful) or hyperalgesia (exaggerated response to noxious stimuli like low-grade inflammation). 1

Functional Abdominal Pain Syndrome

• This diagnosis applies to the subgroup of patients with continuous pain rather than intermittent symptoms. 1
• These patients respond poorly to conventional treatment and often have severe underlying psychological disturbances requiring early recognition. 1

Critical Alarm Features Requiring Investigation

You must actively screen for these red flags that mandate further workup: 1, 3

• Age >50 years at symptom onset 1, 3
• Short history of symptoms (progressive diseases like cancer typically diagnosed within 6 months) 1
• Documented unintentional weight loss 1, 3
• Nocturnal symptoms 1, 3
• Rectal bleeding 3
• Family history of colorectal cancer or inflammatory bowel disease 1, 3
• Male sex (lower pretest probability of functional disease) 1
• Fever 3

Recommended Diagnostic Approach

Initial Laboratory Testing

• For patients under 45 years without alarm features, obtain complete blood count, C-reactive protein or erythrocyte sedimentation rate, celiac serology, and fecal calprotectin. 3
• Stool Hemoccult and complete blood count are recommended for screening purposes. 1
• Consider stool for ova and parasites based on travel history, endemic area exposure, or persistent diarrhea. 1, 3

Fecal Calprotectin Interpretation

• If fecal calprotectin ≥250 μg/g, perform colonoscopy due to high suspicion for IBD. 3
• If 100-249 μg/g, repeat the test off NSAIDs and proton pump inhibitors; consider colonoscopy if it remains abnormal. 3
• If <100 μg/g, this supports a functional diagnosis. 3

Endoscopic Evaluation

• Colonoscopy is recommended for patients over age 50 years due to higher pretest probability of colon cancer. 1
• In younger patients, performing colonoscopy or sigmoidoscopy depends on clinical features suggestive of disease (diarrhea, weight loss) and may not be indicated. 1
• Plain abdominal radiography during an acute episode can exclude bowel obstruction when pain is the predominant symptom. 1

Additional Testing for Persistent Symptoms

• If baseline tests are normal but symptoms persist, consider lactose hydrogen breath test, fructose breath testing, small bowel biopsies, or colonic biopsies via flexible sigmoidoscopy. 3
• For diarrhea-predominant symptoms, serologies for celiac sprue or small bowel/colonic biopsies may be indicated. 1

Making a Positive Diagnosis

If baseline investigations are normal and no alarm features exist, make a positive diagnosis of IBS rather than continuing exhaustive testing. 3, 4

Supportive Clinical Features

• Symptoms present for more than 6 months 1
• Bloating and visible abdominal distension 1, 3
• Abnormal stool frequency or passage of mucus 1, 3
• Urgency or feeling of incomplete evacuation 1, 3
• Patient reports that stress aggravates symptoms 1
• Frequent consultations for non-gastrointestinal symptoms 1

Common Pitfalls to Avoid

• Do not pursue exhaustive testing once functional disease is confidently established; repetitive testing is not recommended. 5
• Recognize that IBS symptoms persist beyond middle life and continue to be reported in the seventh and eighth decades, so age alone should not exclude the diagnosis in older patients without alarm features. 1
• Be aware that proctalgia fugax (brief anorectal pain) occurs in one-third of patients with gastrointestinal symptoms but is not specifically related to IBS; it is usually benign and transient. 6
• If the diagnosis remains uncertain after initial testing, a therapeutic trial (such as loperamide for diarrhea or antispasmodics for pain) can be both diagnostic and therapeutic. 1, 3