Fissure surgery is a procedure to heal a chronic anal fissure, which is a small tear in the lining of the anus that hasn’t responded to non-surgical treatments. The most common version involves making a small cut in the muscle that controls the anal opening, reducing the pressure that prevents the tear from healing. Surgery is typically recommended when a fissure has persisted for more than eight weeks despite medications and lifestyle changes.
Why Surgery Becomes Necessary
Most anal fissures heal on their own or with conservative measures like fiber supplements, warm baths, and topical creams that relax the anal muscles. But some fissures become chronic. The underlying problem is a tight internal sphincter muscle that creates too much pressure in the anal canal, cutting off blood flow to the tear and preventing it from closing. When that cycle of pain, spasm, and poor healing won’t break after eight or more weeks of treatment, surgery addresses the root cause by releasing that excess muscle tension.
Before recommending surgery, your doctor may also try a Botox injection into the sphincter muscle. This temporarily paralyzes part of the muscle, mimicking what surgery does permanently. In a comparative study, Botox healed the fissure in about 73% of patients at six months, while surgery healed 100%. The recurrence rate was also higher with Botox: 20% versus 7% for surgery. So while Botox can work as a middle step, surgery remains the more effective and durable option for fissures that won’t heal.
How the Main Procedure Works
The standard operation is called a lateral internal sphincterotomy. The name sounds complicated, but the concept is straightforward: the surgeon makes a small, controlled cut through part of the internal sphincter muscle on the side of the anus. This permanently lowers the resting pressure inside the anal canal, allowing blood to flow back to the fissure so it can finally heal.
There are two techniques surgeons use. In the open approach, a small incision is made in the skin on the side of the anus, the internal sphincter muscle is identified and separated from the outer sphincter, and a portion is carefully divided. In the closed approach, the surgeon inserts a thin blade through the skin without a visible incision, using a finger inside the canal to guide the cut. Both achieve the same goal. The entire operation usually takes less than 30 minutes and is performed under general or regional anesthesia as an outpatient procedure, meaning you go home the same day.
Healing rates are strong. Studies consistently show about a 90% success rate, with recurrence below 10%.
Sphincter-Sparing Alternatives
A lateral sphincterotomy does carry a real tradeoff: because it permanently divides part of the muscle that helps control bowel function, there is a risk of some degree of incontinence afterward. For certain patients, surgeons choose procedures that avoid cutting the sphincter entirely.
A fissurectomy removes the chronic fissure tissue itself (including any scar tissue or skin tags around it) without touching the sphincter muscle. This eliminates the incontinence risk but comes with a longer healing window, often 10 to 15 weeks, because the wound is left open to close on its own.
To speed that healing, surgeons sometimes combine a fissurectomy with an advancement flap, where a small piece of nearby skin is moved over the wound to close it. Research comparing the two found that the flap approach heals faster than fissurectomy alone while still preserving sphincter function completely. Flap procedures are particularly favored for women who have given birth (whose sphincter may already be slightly weakened), patients with low baseline muscle tone, and anyone with a recurrent fissure after a previous sphincterotomy.
Risks and Side Effects
The most discussed risk of sphincterotomy is changes in bowel control. A five-year study from a high-volume surgical center found that 24.5% of patients experienced some measurable change in continence after the procedure. That number sounds alarming, but the details matter: no patients in the study lost control of solid stool. About 2% had occasional difficulty with liquid stool, and the remaining cases involved difficulty controlling gas. Most patients described these issues as mild and said they didn’t affect daily life.
In the short term, the numbers are higher. As many as 39% of patients experience some transient incontinence in the weeks immediately after surgery, typically difficulty controlling gas or loose stool. These symptoms generally resolve within six to eight weeks as the surgical site heals and the body adjusts to the new muscle balance. About 4% of patients report ongoing defecatory urgency, meaning a sudden, hard-to-delay need to use the bathroom.
Other potential complications include bleeding, infection at the incision site, and, rarely, incomplete healing of the fissure requiring further treatment.
What Recovery Looks Like
Pain after surgery typically peaks in the first few days and improves noticeably between days 7 and 14. Many people describe the post-operative pain as similar to what the fissure itself caused, with the key difference being that it steadily gets better rather than recurring with every bowel movement.
The most important part of recovery is keeping your stool soft so you don’t strain the healing area. This means increasing fiber intake significantly, drinking plenty of water, and using a stool softener daily. Warm water soaks (sitz baths) for about five minutes, two to four times a day, help with pain and keep the area clean. Soaking after every bowel movement is especially helpful during the first couple of weeks.
Return to work depends on the nature of your job. People with desk jobs often go back within a few days to a week. Those with physically demanding work may need two to three weeks. Full tissue healing of the surgical site takes several weeks, but most people notice a dramatic improvement in their original fissure symptoms well before that point. The sharp, burning pain during bowel movements that characterizes a chronic fissure often improves rapidly once the sphincter pressure drops.
Choosing Between Procedures
Your surgeon will recommend a specific approach based on several factors: your sphincter muscle tone (measured during a physical exam or sometimes with a pressure test), whether you’ve had previous anal surgery, your childbirth history, and the location and severity of the fissure.
For most patients with a straightforward chronic fissure and normal sphincter tone, lateral internal sphincterotomy remains the gold standard because of its high success rate and fast symptom relief. If you have any existing risk factors for incontinence, such as prior sphincter injury, multiple vaginal deliveries, or older age, a sphincter-sparing option like fissurectomy with an advancement flap offers healing without putting bowel control at risk. The healing timeline is longer, but the functional tradeoff is worth it for many patients in these groups.