What is the appropriate workup for a patient presenting with tenesmus?

Workup for Tenesmus

Tenesmus—the sensation of incomplete rectal evacuation or bowel urgency with a deferral time under 15 minutes—requires systematic evaluation to identify gastrointestinal pathology, particularly colorectal malignancy in adults, while also considering inflammatory bowel disease, anorectal disorders, and infectious etiologies. 1

Initial Clinical Assessment

History Taking

• Document stool characteristics: presence of blood, mucus, or liquid/very soft consistency 1
• Quantify stool frequency: number of liquid or soft stools per day to establish baseline severity 1
• Assess for rectal bleeding: presence of blood, stripes of blood in stool, or passage of pure blood 1
• Evaluate perianal symptoms: pain, abscess, purulent discharge, or fistula formation around the anus 1
• Screen for bowel incontinence: lack of voluntary control over stool production during daytime 1
• Identify abdominal pain: intensity ranging from mild discomfort to pain limiting activities of daily life 1
• Assess impact on everyday life: ability to carry out physical activities and occurrence of missing planned activities due to symptoms 1

Physical Examination

• Perform abdominal examination: palpate for masses or tenderness 1
• Conduct rectal examination: essential unless significant delay to colonoscopy is anticipated, particularly important when rectal bleeding and tenesmus are present 1
• Inspect perianal region: look for visible fistulas, abscesses, or external hemorrhoids 1

Laboratory Testing

Basic Blood Work

• Complete blood count with differential: detect anemia (hemoglobin <13.5 g/dL in men, <12.0 g/dL in non-pregnant women) that may indicate chronic blood loss 1
• C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR): biomarkers to detect systemic inflammation 1

Stool Studies

• Fecal calprotectin: biomarker to detect intestinal inflammation, particularly useful for inflammatory bowel disease 1
• Stool culture and ova/parasites: if infectious etiology suspected based on acute onset or travel history 2, 3

Endoscopic Evaluation

Colonoscopy (First-Line)

• Colonoscopy is the preferred initial gastrointestinal investigation for tenesmus in adults, as it allows direct visualization, biopsy of lesions, treatment of adenomas, and identification of superficial pathology such as angiodysplasia 1
• Perform colonoscopy even if upper gastrointestinal pathology is identified, as conditions like peptic ulcer disease should not be accepted as the cause until lower GI tract is evaluated 1
• Sensitivity exceeds 90% for lesions >10 mm, making it superior to radiographic alternatives 1

Flexible Sigmoidoscopy

• Consider if full colonoscopy is contraindicated or if symptoms strongly suggest distal colonic or rectal pathology 1
• Obtain biopsies of rectal mucosa even if grossly normal-appearing, to evaluate for microscopic colitis or inflammatory bowel disease 1

Radiographic Imaging (Alternative or Adjunct)

CT Colonography

• Use when colonoscopy is contraindicated or unavailable, with sensitivity >90% for lesions >10 mm 1
• Requires full bowel preparation similar to colonoscopy 1

Barium Enema

• Less reliable than colonoscopy or CT colonography but acceptable if other modalities unavailable 1

Additional Testing Based on Clinical Context

If Inflammatory Bowel Disease Suspected

• Serologic testing for coeliac disease: tissue transglutaminase (tTG) antibody if concurrent iron deficiency anemia or malabsorptive symptoms 1
• Assess disease activity markers: hemoglobin, CRP, and fecal calprotectin to establish baseline 1

If Infectious Etiology Suspected

• Stool testing for Clostridioides difficile if recent antibiotic use or healthcare exposure 2
• Consider sexually transmitted infection testing (gonorrhea, chlamydia, herpes simplex, syphilis) if risk factors present 2

Critical Pitfalls to Avoid

• Do not attribute tenesmus to hemorrhoids or anal fissures without excluding proximal pathology through colonoscopy, as colorectal malignancy can coexist 1
• Do not delay colonoscopy in patients >50 years or those with alarm features (weight loss, anemia, family history of colorectal cancer) 1
• Do not accept upper GI pathology as the sole explanation for tenesmus without completing lower GI evaluation 1
• Do not rely solely on rectal examination, as it has limited sensitivity for detecting proximal lesions 1

Algorithmic Approach

1. Obtain focused history emphasizing red-flag symptoms (rectal bleeding, weight loss, anemia, family history) 1
2. Perform physical examination including abdominal and rectal examination 1, 2
3. Order basic laboratory tests: CBC, CRP/ESR, fecal calprotectin 1
4. Proceed directly to colonoscopy in adults, particularly those >50 years or with alarm features 1
5. Obtain biopsies of any visualized lesions and random biopsies if mucosa appears normal but inflammatory bowel disease suspected 1
6. Consider additional testing (coeliac serology, stool cultures) based on colonoscopy findings and clinical context 1