What are the possible causes and treatments for intermittent rectal pain?

Intermittent Rectal Pain: Diagnosis and Management

For intermittent rectal pain without fever or systemic symptoms, the most likely diagnoses are proctalgia fugax (sudden, brief spasms), anal fissure (sharp pain with defecation), or thrombosed hemorrhoids, and the diagnostic approach should focus on distinguishing these through specific history features and physical examination findings rather than imaging. 1, 2, 3

Key Diagnostic Features to Elicit

History Pattern Recognition

Proctalgia fugax presents with these specific characteristics that distinguish it from other causes:

• Sudden onset cramping, spasm-like, or stabbing pain lasting seconds to 15 minutes (average) 2, 4
• Occurs without trigger factors in 85% of cases 4
• Happens equally during day (33%) and night (35%) 4
• Pain does not radiate in 93% of cases 4
• No concomitant symptoms in 81% of cases 4
• Resolves spontaneously in 67% of cases 4
• Average frequency of 13 attacks per year 4

Anal fissure has a distinctly different pattern:

• Sharp, tearing pain specifically during and after defecation 5, 6
• Associated with minor rectal bleeding 5
• Pain is postdefecatory, not random 5

Thrombosed hemorrhoids present with:

• Acute-onset anal pain with a palpable perianal lump 5
• Continuous pain rather than intermittent episodes 5

Critical Red Flags Requiring Further Investigation

Fever with rectal pain strongly suggests intersphincteric abscess, which is often occult on external examination but causes significant pain on digital rectal examination 1, 6. This represents a surgical emergency requiring prompt drainage 1.

New-onset anal pain without visible external pathology should raise suspicion for small intersphincteric abscess 5.

Physical Examination Approach

Digital Rectal Examination Findings

• Normal examination with classic history confirms proctalgia fugax 2, 3
• Tender, indurated area above the anorectal ring suggests intersphincteric or supralevator abscess 1
• Visible fissure on anal eversion (using opposing traction with thumbs) confirms anal fissure 5
• Palpable perianal lump indicates thrombosed external hemorrhoid 5

Anoscopy Indications

Anoscopy is warranted when:

• Sexual history suggests risk for sexually transmitted proctitis (receptive anal intercourse) 7
• Symptoms include tenesmus, rectal discharge, or bleeding suggesting proctitis 7, 8
• Internal hemorrhoids are suspected 5

When Imaging Is NOT Needed

For proctalgia fugax with typical presentation and normal examination, expensive imaging such as CT or MRI of the pelvis is not required 9. The diagnosis is clinical based on characteristic history and negative physical findings 2, 9.

When Further Evaluation IS Required

Colonoscopy Indications

Any patient with rectal bleeding should not have it attributed to hemorrhoids until the colon is adequately evaluated 5. Hemorrhoids alone do not cause positive fecal occult blood testing 5.

Imaging for Suspected Deep Abscess

MRI, CT scan, or endoanal ultrasound should be considered when:

• Intersphincteric or supralevator abscess is suspected based on pain on digital rectal examination with fever 1
• These deeper abscesses are difficult to diagnose clinically and may be occult on external examination 1

Testing for Proctitis

If symptoms include tenesmus, rectal discharge, or bleeding with appropriate risk factors:

• Obtain sexual history specifically asking about receptive anal intercourse 7
• Perform anoscopy to visualize rectal mucosa 7
• Test for N. gonorrhoeae, C. trachomatis, T. pallidum, and HSV 7
• Examine Gram-stained smear of anorectal exudate for polymorphonuclear leukocytes 7

Management Based on Diagnosis

Proctalgia Fugax Treatment

Reassurance is the most useful therapeutic option 2. Most patients (83%) have never sought medical advice for this benign condition 4.

For frequent and severe attacks:

• Calcium channel blockers such as nifedipine may be tried 9
• The condition results from internal anal sphincter dysfunction and is benign with no known serious etiology 2, 9

Anal Fissure Management

Most anal fissures respond to conservative medical treatment:

• Sitz baths, stool softeners, and analgesics 6
• Pharmacologic treatment with botulinum toxin or nitroglycerin ointment to decrease internal anal sphincter tone 6
• Lateral sphincterotomy reserved for chronic fissures unresponsive to medical therapy 6

Thrombosed External Hemorrhoid

Surgical excision is indicated only if within 48-72 hours of pain onset 6. Beyond this window, conservative management with sitz baths and analgesics is appropriate 6.

Intersphincteric Abscess

Prompt surgical drainage is mandatory once diagnosis is confirmed, as undrained anorectal abscesses can expand into adjacent spaces and progress to systemic infection 1.

Common Pitfalls to Avoid

• Do not attribute rectal bleeding to hemorrhoids without adequate colonic evaluation 5
• Do not miss intersphincteric abscess in patients with fever and pain on digital rectal examination—these require imaging and surgical drainage 1
• Do not order expensive imaging for typical proctalgia fugax with normal examination 9
• Do not overlook sexually transmitted proctitis in patients with appropriate risk factors—obtain detailed sexual history 7
• Recognize that 20% of patients with hemorrhoids have concomitant anal fissures 5