Anal Fissure Treatment — How It Works, Benefits & Recovery — Procedure Guide, Recovery & Risks | MyMedicPlus

An anal fissure is a painful tear or ulceration of the mucosa and squamous epithelium lining the anal canal, most commonly occurring in the posterior (6 o'clock) midline position — the site of poorest blood supply. It causes severe, lancinating pain during and after defaecation (described by patients as 'passing broken glass'), often followed by a dull throbbing ache lasting 1–2 hours, with bright red rectal bleeding on toilet paper. Fissures are classified as acute (under 6 weeks, with a clean tear) or chronic (over 6 weeks, characterised by indurated edges, a hypertrophied anal papilla at the proximal end, and a sentinel skin tag at the distal end). The underlying pathophysiology involves internal anal sphincter hypertonia — elevated resting anal canal pressure impairs perfusion of the mucosa, creating an ischaemic non-healing wound. Treatment aims to reduce sphincter pressure to restore mucosal blood flow and allow healing. Management is stepwise: conservative dietary measures → topical chemical sphincterotomy → pharmacological sphincter relaxation → injection therapy → surgical lateral internal sphincterotomy (LIS). Colorectal surgeons and proctologists lead surgical management. Anal fissures affect approximately 1 in 350 adults per year in the UK.

All symptomatic anal fissures require treatment; the approach is tailored to acuity and patient factors. Conservative measures (adequate dietary fibre 25–35 g/day, increased fluid intake to 2 litres/day, warm sitz baths for 15–20 minutes three times daily) are commenced for all patients as initial therapy and continued throughout all subsequent treatments. Acute fissures (under 6 weeks) heal spontaneously with conservative measures alone in approximately 50% of cases. Topical vasodilators (glyceryl trinitrate 0.4% ointment applied 3 times daily, or diltiazem 2% cream) are prescribed for fissures persisting beyond 2–3 weeks or causing severe symptoms; they heal 60–70% of chronic fissures. Botulinum toxin A injection (20–40 units into the internal anal sphincter in clinic under local anaesthesia) is indicated when topical therapy fails or in patients with contraindications to topical therapy — it heals 60–80% without incontinence risk. Lateral internal sphincterotomy (LIS) — a 15–30 minute day surgical procedure under local or general anaesthesia — is indicated for fissures failing 3 months of maximal medical therapy or two courses of botulinum toxin, or patients who prefer definitive surgical treatment. Patients with Crohn's disease or HIV-associated fissures require specialist management as standard sphincterotomy carries elevated incontinence and poor healing risks.

Topical glyceryl trinitrate (GTN) 0.4% ointment is applied to the anal canal and perianal skin three times daily by the patient at home using a gloved finger. GTN releases nitric oxide, relaxing the internal sphincter — headache is the most common side effect (reported in 20–30% of patients) and may limit compliance. Diltiazem 2% cream is an alternative with fewer headaches and comparable efficacy. Botulinum toxin A injection is performed in the outpatient clinic with the patient in the lithotomy or lateral position under local anaesthesia. A total of 20–40 units of botulinum toxin (Botox or Dysport) is injected into both sides of the internal anal sphincter using a fine needle — paralysis reduces resting sphincter pressure within 3–5 days, allowing fissure healing over 4–8 weeks. Lateral internal sphincterotomy (LIS) is performed under local or general anaesthesia. The patient is positioned in the lithotomy position. A small 1 cm incision is made in the lateral anal canal (3 or 9 o'clock position) and the intersphincteric groove identified. The lower third to half of the internal anal sphincter is divided under direct vision (open technique) or with a blade through a very small incision (closed technique), reducing resting sphincter pressure and restoring blood supply. The wound is closed with a single absorbable suture. Open LIS has lower risk of inadvertent injury than closed technique.

Effective treatment of anal fissure provides dramatic relief from a severely debilitating condition — many patients with chronic fissures are significantly disabled by pain, fear of defaecation, and consequent constipation that worsens the fissure. Lateral internal sphincterotomy achieves the highest cure rate of any intervention: 90–95% long-term healing in published series, with rapid pain relief beginning within 48–72 hours of surgery. This compares favourably with 60–70% healing from topical GTN or diltiazem (with high relapse rates on stopping) and 60–80% with botulinum toxin injection (30–40% relapse requiring repeat injections or eventual LIS). The graduated approach allows most patients to avoid surgery entirely using medical management. For surgical LIS, the procedure takes only 15–30 minutes as a day case. In India, outpatient botulinum toxin injection for anal fissure costs approximately INR 5,000–15,000 (USD 60–180), and surgical LIS approximately INR 20,000–50,000 (USD 240–600) — compared to USD 3,000–8,000 in the USA. Recovery is rapid and most patients return to work within 1 week of LIS.

Topical GTN causes headache in 20–30% of patients (often dose-limiting) and postural hypotension; diltiazem cream causes significantly fewer headaches and is a preferred alternative. Both topical agents have high relapse rates (40–50%) after stopping treatment. Botulinum toxin injection carries a 3–8% risk of temporary minor incontinence to flatus or liquid stool (resolving within 2–3 months as the toxin effect wears off), and a 30–40% recurrence rate requiring repeat injections. Lateral internal sphincterotomy, whilst highly effective, carries a small but important risk of incontinence: minor transient incontinence to flatus in 5–15% of patients, which usually resolves within 3 months; permanent incontinence affecting bowel control occurs in under 1% when only the lower third to half of the internal sphincter is divided. Women who have sustained obstetric sphincter injuries are at elevated incontinence risk from LIS and should be offered manometry and endoanal ultrasound before surgery. Other LIS risks include infection (1–2%), haematoma, and non-healing (1–3%). Misidentification of chronic fissure as an atypical fissure from Crohn's disease, sexually transmitted infection, or cancer is a critical diagnostic risk — any fissure off the posterior midline, multiple fissures, or fissures not responding to standard treatment require biopsy.

After lateral internal sphincterotomy, significant pain relief is typically experienced within 24–72 hours. Wound healing is confirmed at 4–8 weeks post-surgery. Post-operative management: warm sitz baths (20 minutes, three times daily) soothe the wound and maintain hygiene; stool softeners (lactulose or Movicol) and a high-fibre diet (25–35 g/day) maintain soft, easy-to-pass stools throughout the healing period and as a long-term preventive measure. Oral analgesia with paracetamol and ibuprofen alternated manages post-operative discomfort; topical lidocaine ointment applied before defaecation provides local pain relief. Wound review at 2 and 6 weeks post-surgery assesses healing progress. Return to desk work is typically at 2–5 days; physical labour at 2–3 weeks. Driving can resume when comfortable — usually 3–5 days. After botulinum toxin injection, effects begin within 3–7 days and healing typically occurs within 4–8 weeks; patients are reviewed at 8–12 weeks to assess fissure healing and continence. Lifelong dietary measures (adequate fibre, fluid, avoidance of straining) significantly reduce fissure recurrence regardless of the treatment modality used.