Diagnostic Approach for Anal Fissures
Anal fissures are diagnosed primarily through visual inspection by gently spreading the buttocks to efface the anal canal—digital rectal examination is contraindicated due to severe pain and provides no additional diagnostic value. 1, 2
Clinical Diagnosis Based on History
The diagnosis should be suspected from history alone before any physical examination 1, 2:
- Pain pattern: Severe anal pain occurring during and immediately after defecation, potentially lasting many hours in chronic cases 1
- Bleeding characteristics: Scanty, bright red blood on toilet paper or stool surface 1
- Patients typically present with a characteristic history that makes the diagnosis highly likely before examination 1
Physical Examination Technique
The correct examination method involves visual inspection only 1, 2:
- Gently spread the buttocks with opposing traction to efface the anal canal and visualize the anal verge 1, 2
- Look for a linear split in the squamous epithelium at or just inside the anal verge 1, 2
- 90% of fissures are located in the posterior midline, with anterior fissures occurring in 10% of women versus 1% of men 2
What NOT to Do
Avoid instrumentation of the anal canal when fissure is suspected 1, 2:
- Digital rectal examination is contraindicated due to the severe pain it causes and rarely yields additional diagnostic information 1, 2
- End-viewing endoscopes cannot visualize fissures given their location 1
- Anoscopy should be deferred in the acute setting when pain is severe 1
Associated Physical Findings in Chronic Fissures
Look for signs of chronicity during visual inspection 1, 2:
- Sentinel skin tag just distal to the fissure 1, 2
- Hypertrophied anal papilla at the proximal margin 1, 2
- Fibrosis at the fissure edges 1, 2
- Visible internal sphincter muscle at the fissure base 1, 2
When Examination Under Anesthesia is Warranted
If severe pain prevents adequate visual examination, examination under anesthesia should be performed rather than forcing an awake examination 1, 2
Red Flags Requiring Further Evaluation
Off-midline fissures mandate workup for underlying disease 1:
- Consider Crohn's disease, HIV/AIDS with secondary infections, ulcerative colitis, tuberculosis, syphilis, leukemia, or malignancy 1
- Imaging may be warranted in atypical presentations to rule out occult perianal sepsis, complex anal fistula, inflammatory bowel disease, or colorectal cancer 2
Common Diagnostic Pitfall
Approximately 20% of patients with hemorrhoids have concomitant anal fissures, so anal pain should not be automatically attributed to hemorrhoids without thorough visual examination 2
Role of Imaging
Imaging is not needed for typical anal fissure diagnosis, as the condition is diagnosed clinically through history and visual inspection 2