An anal fissure is a linear tear in the anal canal, typically extending from the dentate line toward the anal verge. It is one of the most common benign anorectal conditions, most frequently located in the posterior midline (73%), with anterior midline fissures occurring in 13% of women and 8% of men. [1] The pathognomonic symptom is sharp, tearing anal pain during and after defecation, often described as "passing glass". [1-2]
1. History
- Pain character: Sharp, cutting, or tearing sensation during defecation, often persisting for minutes to hours afterward [1][3]
- Bleeding: Bright red blood on toilet tissue, typically small volume, associated with bowel movements [1][4]
- Timing: Onset often follows passage of a hard stool or episode of diarrhea [1][4]
- Progression: Acute (<6 weeks) vs. chronic (>6–12 weeks); healing rates with conservative therapy decrease as symptom duration increases — 100% healing at <1 month vs. 33% at >6 months [1]
- Associated symptoms: Anal spasm, pruritus, sentinel skin tag noticed by patient (often described as a "painful hemorrhoid") [4]
- Important negatives: Absence of fever, purulent drainage (abscess/fistula), weight loss, change in bowel caliber (malignancy), or perianal fistulous openings
2. Alarm Features
- Lateral or multiple fissures → must evaluate for Crohn disease, HIV, syphilis, tuberculosis, hematologic malignancy [1][4]
- Fissures off the midline → raise concern for IBD, infections, and neoplasia [2][4]
- Bleeding independent of bowel movements → concerning for anorectal cancer [5]
- Non-healing despite adequate therapy → consider underlying malignancy or Crohn disease
- Constitutional symptoms (weight loss, night sweats, fever) → suggest systemic disease
- Significant rectal bleeding disproportionate to fissure → warrants endoscopic evaluation
3. Medications
- Acute fissure first-line: Sitz baths, fiber supplements (psyllium), topical anesthetics (lidocaine), stool softeners [1]
- Chronic fissure — topical calcium channel blockers (preferred first-line): Diltiazem 2% or nifedipine 0.3% ointment applied BID for 6–8 weeks; healing rates ~67–90%; fewer headaches than nitrates [1][4][6]
- Topical nitrates: Nitroglycerin 0.2–0.4% ointment BID; ~50% healing rate; headache in ≥30% of patients, leading to cessation in up to 20% [1][7]
- Botulinum toxin A: 5–100 units injected into internal anal sphincter; ~67% healing; 5% transient fecal incontinence; no clear dose-response relationship [1][4]
- Contraindicated/cautions: Avoid topical nitroglycerin with PDE-5 inhibitors (sildenafil, tadalafil) due to severe hypotension risk; use caution with oral CCBs due to systemic side effects [1][4]
4. Diet
- High-fiber diet (25–35 g/day) is foundational for both acute and chronic fissures — softens stool and reduces trauma to the anal canal [1][8]
- Adequate hydration (at least 1.5–2 L/day) to complement fiber intake
- Avoid constipating foods (processed foods, excessive dairy, low-fiber diets)
- Maintenance fiber after healing reduces recurrence: 16% recurrence with fiber vs. 60% with placebo [1]
5. Review of Systems
- GI: Bowel habits (constipation vs. diarrhea), straining, stool consistency, blood in stool, mucus, tenesmus, abdominal pain
- Constitutional: Weight loss, fever, night sweats (IBD, malignancy, TB, HIV)
- Dermatologic: Perianal rash, psoriatic lesions, ulcers elsewhere (Behçet, Crohn)
- GU/Obstetric: Prior vaginal deliveries, obstetric injuries (relevant for surgical planning) [1]
- Sexual history: Receptive anal intercourse, STI risk factors
6. Collateral History and Family History
- Family history of IBD (Crohn disease in particular) — associated with atypical/lateral fissures [4]
- Family history of colorectal cancer — if bleeding is atypical, warrants further workup [5]
- Social context: Toileting habits, straining behavior, dietary patterns
- Obstetric history in women: Prior sphincter injuries affect surgical candidacy [1]
7. Risk Factors
- Constipation — most common precipitant [1-2]
- Chronic diarrhea — less common but recognized cause [1]
- Low-fiber diet and inadequate fluid intake
- Pregnancy and postpartum — increased risk due to constipation and vaginal delivery trauma [2]
- Prior anorectal surgery
- Crohn disease and other inflammatory conditions
- Hypertonic internal anal sphincter — central to pathogenesis of chronicity [1][8]
8. Differential Diagnosis
- Hemorrhoids (thrombosed external) — palpable lump, less sharp pain, may not be defecation-triggered [5][9]
- Perianal abscess — constant throbbing pain, erythema, swelling, fever, purulent drainage [5]
- Anal fistula — chronic drainage, history of prior abscess [5]
- Anorectal cancer — bleeding independent of bowel movements, mass, weight loss [4-5]
- Crohn disease — lateral/multiple fissures, other GI symptoms, perianal disease [1][4]
- STIs (syphilis, herpes, chlamydia/LGV) — atypical location, ulceration, lymphadenopathy
- Perianal dermatitis/psoriasis — pruritus predominant, skin changes [4]
- Tuberculosis — atypical fissure in endemic areas [4]
- Solitary rectal ulcer syndrome — straining, mucus, rectal pain
The following figure from JAMA illustrates conditions commonly mistaken for hemorrhoidal disease, including anal fissure, with distinguishing clinical features:
9. Past Medical History
- Prior anal fissures or anorectal surgery
- IBD (especially Crohn disease)
- HIV/immunosuppression
- Chronic constipation or IBS-C
- Obstetric history (vaginal deliveries, sphincter tears)
- Baseline fecal incontinence — critical before considering sphincterotomy [1]
10. Physical Exam
- Inspection: Gently separate buttocks with opposing traction to visualize the anal verge — fissure appears as a linear tear, most commonly posterior midline [10]
- Sentinel skin tag at distal margin and hypertrophied anal papilla proximally suggest chronicity [1][4]
- Exposed internal sphincter fibers at the fissure base = chronic fissure [1]
- Digital rectal exam: Exquisite tenderness at the fissure site; assess sphincter tone (often hypertonic); may be too painful to perform — defer if severe [2-3]
- Anoscopy: Rarely needed for diagnosis; avoid in acute setting with severe pain; consider examination under anesthesia if diagnosis uncertain [10]
- Vital signs: Generally normal; fever suggests abscess or systemic infection
11. Lab Studies
- Routine labs are not indicated for typical acute anal fissure [3]
- If atypical fissure or suspicion for secondary cause:
- CBC — anemia from chronic bleeding; leukocytosis (abscess); cytopenias (hematologic malignancy)
- HIV testing — if lateral/multiple fissures or risk factors
- RPR/VDRL — if syphilis suspected
- ESR/CRP — if IBD suspected
- TB testing — in endemic populations with atypical fissures
- Stool studies if chronic diarrhea is the precipitant
12. Imaging
- No imaging is necessary for typical acute anal fissure [3]
- Endoanal ultrasound — may be used to assess sphincter integrity before surgical planning
- MRI pelvis — if concern for occult perianal sepsis, fistula, or Crohn perianal disease [3]
- CT scan — only if concern for deep abscess or other pelvic pathology
- Colonoscopy — indicated if bleeding is atypical, family history of CRC, change in bowel habits, or age-appropriate screening is due [5]
13. Special Tests
- Anorectal manometry — documents internal anal sphincter hypertonia; useful before surgical intervention to assess baseline sphincter function [4]
- Anoscopy — for visualization of internal pathology when diagnosis is uncertain; avoid in acute severe pain [10]
- Examination under anesthesia (EUA) — when pain precludes adequate office exam or when concomitant abscess/fistula is suspected [3][10]
14. ECG
- Not routinely indicated for anal fissure
- Consider if planning procedural sedation for EUA or surgical intervention
- Be aware of potential hypotension with topical nitroglycerin use, particularly in patients on concurrent vasodilators or PDE-5 inhibitors
15. Assessment
- Acute fissure (<6 weeks): Superficial tear with well-demarcated edges; excellent prognosis with conservative management (~50% heal with sitz baths and fiber alone) [1][3]
- Chronic fissure (>6–12 weeks): Sentinel tag, hypertrophied papilla, exposed sphincter fibers; driven by internal anal sphincter hypertonia and local ischemia; requires pharmacologic or surgical intervention [1][4]
- Typical presentation: Posterior midline, sharp defecation-related pain, minimal bright red bleeding
- Atypical presentation: Lateral, multiple, or non-healing fissures → mandates workup for Crohn, HIV, STIs, malignancy [1][4]
- Complications: Chronic pain, fecal avoidance behavior worsening constipation, secondary abscess/fistula formation (rare)
16. Treatment Plan
Acute fissure (first-line)
- Sitz baths (warm water, 10–15 min, 2–3 times daily) [1]
- Fiber supplementation (psyllium or equivalent, 25–35 g/day) + adequate fluids [1]
- Topical anesthetics (lidocaine ointment) for symptomatic relief
- Stool softeners (docusate) as adjunct
Chronic fissure — stepwise approach
- Topical calcium channel blocker (preferred): Diltiazem 2% ointment BID × 6–8 weeks — similar efficacy to nitrates with fewer side effects (headache RR 0.39 vs. GTN) [1]
- Topical nitroglycerin 0.2% BID × 8 weeks — alternative if CCB unavailable; ~50% healing; headache common [1]
- Botulinum toxin A injection (20–100 units into internal sphincter) — second-line after failed topical therapy; ~67% healing; may be combined with topical nitrates for improved efficacy [1][7]
- Lateral internal sphincterotomy (LIS) — gold standard surgical treatment; 88–100% healing rates; reserved for patients failing medical therapy without baseline fecal incontinence [1]
17. Disposition
- Discharge (vast majority): Typical acute fissure — initiate conservative management, provide return precautions
- Observation/admission criteria: Rarely needed; consider if severe uncontrolled pain requiring parenteral analgesia, or if concomitant perianal abscess requiring drainage
- Specialist consultation triggers:
- Chronic fissure failing 6–8 weeks of topical therapy → colorectal surgery [1]
- Atypical fissure (lateral, multiple, non-healing) → GI and/or colorectal surgery for biopsy and workup [1][4]
- Suspected Crohn disease or malignancy → gastroenterology
- Baseline fecal incontinence complicating surgical decision-making → colorectal surgery with manometry [1]
18. Follow Up / Return Precautions
- Follow-up: Primary care or GI in 2–4 weeks to assess response to conservative therapy; chronic fissures should be reassessed at 6–8 weeks [1]
- Maintenance fiber long-term after healing to prevent recurrence (recurrence 16% with fiber vs. 60% without) [1]
- Return immediately for:
- Increasing pain, fever, or swelling (abscess)
- Heavy rectal bleeding or blood clots
- Purulent drainage (fistula/abscess)
- Inability to have bowel movements
- Expected course: Acute fissures typically heal within 4–6 weeks with conservative measures; chronic fissures may require 8–12 weeks of topical therapy; surgical healing is rapid (days to weeks) but carries small risk of long-term fecal incontinence (8–30% depending on follow-up) [1]
- Patient counseling: Emphasize that this is a common, benign condition; adherence to fiber and fluid intake is critical; avoid straining; topical medications may cause headache but are temporary
References
1. The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Management of Anal Fissures. — Davids JS, Hawkins AT, Bhama AR, et al. Diseases of the Colon and Rectum. 2023.
2. Constipation, Hemorrhoids, and Anorectal Disorders in Pregnancy. — Rao SSC, Qureshi WA, Yan Y, Johnson DA. The American Journal of Gastroenterology. 2022.
3. Anorectal Emergencies: WSES-AAST Guidelines. — Tarasconi A, Perrone G, Davies J, et al. World Journal of Emergency Surgery : WJES. 2021.
4. ACG Clinical Guidelines: Management of Benign Anorectal Disorders. — Wald A, Bharucha AE, Limketkai B, et al. The American Journal of Gastroenterology. 2021.
5. Hemorrhoidal Disease. — Ashburn JH. The Journal of the American Medical Association. 2025.
6. A Double-Blind Randomised Controlled Trial Comparing the Efficacy of Nifedipine and Diltiazem Ointments in the Treatment of Anal Fissure. — Kumar A, Garg R, Gupta P, Ranjan P. World Journal of Surgery. 2026.
7. Management of Anal Fissures: Guidelines From the American Society of Colon and Rectal Surgeons. — Arnold MJ. American Family Physician. 2024.
8. Anal Fissures. — Chiu A, Donahue S, Torgersen Z, Ternent C. The Surgical Clinics of North America. 2026.
9. American Gastroenterological Association Technical Review on the Diagnosis and Treatment of Hemorrhoids. — Madoff RD, Fleshman JW, Clinical Practice Committee, American Gastroenterological Association. Gastroenterology. 2004.
10. American Gastroenterological Association Medical Position Statement: Diagnosis and Care of Patients With Anal Fissure. — Gastroenterology. 2003.