Most Common Diagnosis: Anal Fissure
In a 43-year-old male presenting with bloody stools and pain on defecation, anal fissure is the most common diagnosis. 1
Key Diagnostic Features
The combination of painful defecation with rectal bleeding is pathognomonic for anal fissure:
- Postdefecatory pain is the cardinal symptom of anal fissure, distinguishing it from other causes of rectal bleeding 1
- Anal fissure frequently causes minor bright red rectal bleeding in addition to pain 1
- Pain associated with a palpable lump suggests thrombosed external hemorrhoid, but hemorrhoids typically do NOT cause pain unless thrombosed 1
- Perianal abscess is equally common as a cause of painful defecation but presents with throbbing continuous pain, swelling, and induration rather than postdefecatory pain 1, 2
Why Not Hemorrhoids?
While hemorrhoids are the most common cause of painless rectal bleeding 3, they are unlikely in this case:
- Anal pain is generally NOT associated with hemorrhoids unless thrombosis has occurred 1
- Bleeding from hemorrhoids is typically bright red, dripping or squirting into the toilet bowl, but painless 1
- Up to 20% of patients with hemorrhoids have concomitant anal fissures, making fissure the more likely primary diagnosis when pain is present 1
Diagnostic Approach
Physical Examination
- Anal fissure is best visualized by everting the anal canal with opposing traction using the thumbs 1
- Most fissures are posterior and midline, related to constipation or anal trauma 4
- External examination will reveal any thrombosed external hemorrhoids, skin tags, or perianal abscess 1
- Digital rectal examination may be too painful in acute fissure but helps exclude abscess (tender indurated area above anorectal ring) 1
Red Flags Requiring Further Evaluation
- Lateral fissures suggest secondary causes: inflammatory bowel disease, previous anal surgery, venereal disease, or malignancy 5
- Fever, swelling, or systemic signs suggest perianal abscess requiring urgent evaluation 1
- Atypical bleeding patterns or risk factors for colorectal neoplasia warrant colonoscopy 1
Critical Pitfall to Avoid
Do not assume hemorrhoids without proper anorectal examination including anoscopy—other pathology is too often overlooked when hemorrhoids are simply assumed 1, 3. The presence of pain with defecation mandates closer investigation beyond hemorrhoids 1.
Age-Specific Considerations
At 43 years old, this patient falls within the typical age range for anal fissure (mean age 40 years for fistula-in-ano, similar for fissures) 1. In contrast, diverticular bleeding and angiodysplasia are more common causes of lower GI bleeding in patients over 70 years 1.