Is an anal fissure palpable during a rectal exam?

Anal Fissures and Rectal Examination

Anal fissures are not typically palpable during a rectal examination and diagnosis is primarily made by visual inspection rather than palpation. 1

Diagnostic Approach for Anal Fissures

Physical Examination

• Anal fissures are best visualized by effacing the anal canal with opposing traction on the buttocks, not through digital rectal examination 1
• Digital rectal examination may actually be contraindicated in suspected anal fissures due to the severe pain it can cause 1
• Fissures are splits in the squamous epithelium at or just inside the anal verge, making them visible on external examination 1
• Most fissures (90%) are located posteriorly in the midline, with anterior fissures occurring in 10% of women versus 1% of men 1

Associated Physical Findings

• Chronic fissures may have associated findings that can be visualized (not palpated):
  • Sentinel skin tag just distal to the fissure 1
  • Hypertrophied anal papilla at the proximal margin 1
  • Fibrosis and visualization of bare internal sphincter muscle at the fissure base 1

When to Suspect Atypical Causes

• Fissures occurring off the midline (lateral) or multiple fissures warrant further investigation for underlying conditions such as:
  • Inflammatory bowel disease (particularly Crohn's disease) 1
  • HIV/AIDS and associated infections 1
  • Tuberculosis 1
  • Malignancy 1, 2
  • Sexually transmitted diseases 1

Diagnostic Challenges and Pitfalls

Pain Management During Examination

• In cases of severe pain, instrumentation of the anal canal is inappropriate and traumatic 1
• When significant anal pain prevents proper examination, examination under anesthesia may be warranted 1

Differential Diagnosis

• Anal pain is often mistakenly attributed to hemorrhoids when it may actually be due to:
  • Anal fissure 1
  • Perianal abscess 1
  • Anal fistula 1

Imaging Considerations

• Imaging is not typically needed for diagnosis of typical anal fissures 1
• In atypical presentations, imaging may be warranted to rule out:
  • Occult perianal sepsis 1
  • Complex anal fistula 1
  • Underlying inflammatory bowel disease 1
  • Anal or colorectal cancer 1

Clinical Pearls

• The diagnosis of anal fissure should be suspected based on history alone (anal pain during and after defecation, scanty bright red bleeding) 1
• Fissures cannot be visualized with end-viewing endoscopes 1
• New-onset anal pain without a visible source should raise suspicion for a small intersphincteric abscess 1
• Approximately 20% of patients with hemorrhoids have concomitant anal fissures, highlighting the importance of thorough visual examination 1

In summary, anal fissures are diagnosed through careful visual inspection rather than palpation during rectal examination. The severe pain associated with fissures often makes digital examination difficult or impossible without anesthesia.