Anal Fissure: Pain, Healing and When Surgery Helps

Pass a hard stool once, and the anal lining — rich in nerve endings — can tear. The muscle beneath it clamps in spasm to protect the injury. That spasm pulls the wound open wider every time you pass stool and squeezes the small arteries that would otherwise heal it. This is the fissure cycle: tear → spasm → pain → harder stool (because you avoid the toilet) → bigger tear. Treatment exists to break the cycle at every point.

Symptoms That Point to a Fissure

• Sharp, burning pain during and especially after passing stool — patients often describe it as "passing glass"; the ache can last hours.
• Bright-red blood as streaks on the stool surface or on the paper — small amounts.
• Fear of the toilet, which worsens constipation and deepens the cycle.
• In chronic fissures: an external skin tag ("sentinel pile") and sometimes a visible wound at the anal opening.

Acute vs Chronic — The 6–8 Week Divide

The single most useful thing you can do in the acute phase is make stool soft and non-painful to pass: 25–30 g fibre daily, 2–3 litres of fluid, a fibre supplement if needed, and warm sitz baths after each bowel movement. Do not postpone toilet visits — every painful hold deepens the cycle.

When Surgery Is Advised

If a chronic fissure fails medical treatment, the standard operation is lateral internal sphincterotomy: a precise, tiny division of the tight internal sphincter muscle, done as a day-care procedure. Cutting the spasm restores blood flow to the wound — and with the cycle broken, fissures heal in about 9 out of 10 patients, with durable long-term results.

The honest trade-off: dividing part of the sphincter carries a small risk (a few percent in experienced hands) of temporary or, rarely, permanent difficulty controlling gas or stool. Surgeons weigh this against your sphincter tone, previous childbirth injury, age and symptoms — which is why the decision is individual. Less-invasive alternatives (botulinum toxin injection, or calibrated procedures) exist and may be suggested where sphincter-sparing matters most.

Fissure and piles get confused constantly — both can bleed, but the pain patterns are opposite: fissure hurts, piles usually don't. Our anal fissure treatment page and piles page describe the full treatment range, and our surgical team assesses these daily.