What is the initial workup for a patient presenting with rectal pain?

Workup for Rectal Pain

The initial workup for rectal pain should include a focused medical history, complete physical examination with digital rectal examination, and appropriate laboratory tests to rule out common causes and identify potentially serious conditions requiring urgent intervention. 1

Initial Clinical Assessment

History

• Pain characteristics: onset, duration, quality, radiation, aggravating/alleviating factors
• Associated symptoms: bleeding, discharge, changes in bowel habits, tenesmus
• Risk factors: recent trauma, surgery, sexual practices, inflammatory bowel disease
• Systemic symptoms: fever, weight loss, night sweats (alarm symptoms)

Physical Examination

• Digital rectal examination is essential and should include:
  • Assessment of sphincter tone
  • Evaluation for masses, tenderness, or fluctuance
  • Examination of the puborectalis muscle (tenderness suggests levator ani syndrome)
  • Testing for expulsive function by asking patient to "expel examiner's finger" 1
  • Evaluation for fissures, fistulas, abscesses, or external hemorrhoids

Laboratory Tests

• Complete blood count to assess for infection or anemia 1
• Basic metabolic panel to evaluate renal function 2
• Inflammatory markers (C-reactive protein, procalcitonin) if infection or inflammation suspected 1
• Consider stool tests for occult blood, ova and parasites, or culture if infectious etiology suspected

Imaging Studies

• For patients with suspected structural abnormalities, defecography (fluoroscopic cystocolpoproctography) is recommended as the first-line imaging test 2
• MRI is preferred for suspected complex fistulas, occult supralevator abscesses, or perianal Crohn's disease 2
• For rectal cancer concerns, endoscopic rectal ultrasound (for early tumors) or rectal MRI is required 1
• For suspected anorectal foreign bodies, lateral and anteroposterior plain X-ray films of abdomen and pelvis are recommended 1

Endoscopic Evaluation

• Anoscopy for direct visualization of the anal canal and distal rectum
• Rigid proctoscopy with biopsy for suspected rectal cancer 1
• Complete colonoscopy if:
  • Patient is >50 years with no prior screening
  • Presence of alarm symptoms (bleeding, weight loss, anemia)
  • Suspected inflammatory bowel disease 1

Specialized Testing

• Anorectal manometry for suspected pelvic floor dysfunction
• Defecography for suspected prolapse, rectocele, or other anatomic abnormalities 1
• Transit studies if constipation is a prominent feature 1

Common Diagnostic Pitfalls

1. Inadequate digital rectal examination: Many clinicians perform cursory examinations that miss important findings. A thorough examination should include assessment of pelvic floor motion during simulated evacuation 1

2. Overreliance on imaging: While imaging is valuable, the diagnosis of many anorectal conditions remains primarily clinical. Unnecessary imaging increases costs without improving outcomes 3

3. Failure to consider functional causes: After excluding organic pathology, functional disorders should be considered rather than pursuing repetitive testing 3

4. Missing serious conditions: Always consider rectal cancer in patients with persistent symptoms, especially those >50 years old 1

5. Overlooking systemic conditions: Rectal pain can be a manifestation of systemic diseases like inflammatory bowel disease or sexually transmitted infections 2, 4

The workup should be tailored based on the suspected etiology, with prompt surgical consultation for conditions like anorectal abscesses that require drainage, or suspected rectal prolapse that may require surgical intervention 1, 5.