Fissure surgery is not considered dangerous. It’s one of the most straightforward procedures in colorectal surgery, with a complication-free success rate of about 96% and a low risk of serious problems. That said, it does carry specific risks worth understanding before you decide to go ahead, particularly around bowel control in the weeks and months after the procedure.
The standard surgery for a chronic anal fissure is called a lateral internal sphincterotomy. A surgeon makes a small cut in part of the internal sphincter muscle, the ring of muscle that keeps your anal canal closed. When you have a chronic fissure, this muscle goes into spasm, cutting off blood flow to the tear and preventing it from healing. The surgery releases that spasm, restores blood flow, and the fissure typically heals on its own afterward.
How Effective the Surgery Is
Sphincterotomy heals chronic anal fissures in roughly 96% of patients. Recurrence rates are low, generally between 1% and 8% depending on the study and how long patients are followed. In one study of nearly 500 patients, only 1.3% experienced a recurrence after healing. When fissures do come back, about two-thirds heal with conservative measures like fiber supplements and topical treatments, meaning a second surgery is rarely needed.
The Main Risk: Changes in Bowel Control
The most talked-about risk of fissure surgery is some degree of incontinence, because the procedure involves cutting a portion of the muscle responsible for holding things in. This sounds alarming, but the details matter.
Temporary difficulty controlling gas affects roughly 4 to 6% of patients. In one study, all cases of gas incontinence resolved within a week. Temporary loss of stool control is less common, occurring in about 2% of patients, and typically resolves within two weeks. In that same study, no patients experienced permanent incontinence to gas or stool.
Longer-term data tells a slightly different story. A follow-up study averaging more than five years after surgery found that 6% of patients still reported occasional gas incontinence, 8% had minor fecal soiling, and 1% experienced loss of solid stool. These numbers sound significant, but context helps: only 3% of all patients said incontinence had ever affected their quality of life. For most people, the episodes were infrequent and minor enough to be a non-issue in daily life.
The overall range for fecal incontinence after sphincterotomy reported across studies is 1.5 to 8%. The wide range reflects differences in how aggressively the sphincter is cut, patient anatomy, and how incontinence is measured. Newer techniques that cut less of the muscle have pushed rates toward the lower end.
Other Possible Complications
Beyond incontinence, the complication list is short. Delayed healing occurs in about 3% of patients, meaning the fissure takes longer than expected to close but still eventually does. Abscess formation at the surgical site is uncommon, reported at around 0.5 to 1% in most studies. Serious infection is extremely rare.
Urinary retention, difficulty urinating after the procedure, is a complication tied more to the type of anesthesia than the surgery itself. Spinal anesthesia can cause urinary retention in up to 36% of patients, while general anesthesia drops that to around 3%. Many surgeons now perform the procedure under local anesthesia alone, which reduces urinary retention to about 0.5% and avoids the risks associated with being put under entirely.
What Recovery Looks Like
Pain after anorectal surgery is moderate on the first day, averaging about a 5 out of 10. For most patients, it drops to mild levels within 7 to 10 days. Some people experience more intense pain initially (above 7 out of 10 on day one) that steadily improves over the first week and a half. Pre-surgery anxiety and how much pain you were already dealing with before the procedure are both predictors of how much postoperative pain you’ll have.
Most patients are pain-free by about six weeks. Complete wound healing takes an average of 10 weeks, with a range from about 6 weeks to several months in slower cases. The procedure is typically done as a short-stay or outpatient surgery, so you go home the same day.
How It Compares to Non-Surgical Options
Surgery is generally reserved for fissures that haven’t healed after weeks of conservative treatment, including topical medications that relax the sphincter muscle. If you’re weighing surgery against other options, Botox injections are the main alternative procedure.
Botox works by temporarily paralyzing the sphincter muscle to achieve a similar relaxation effect. It carries a lower risk of incontinence than surgery, and it’s simpler to perform. The tradeoff is a significantly higher recurrence rate. Fissures come back much more often after Botox than after sphincterotomy. For that reason, Botox is sometimes used as a first step, especially in patients who want to avoid the permanence of cutting the muscle, with surgery held in reserve if the fissure returns.
Who Faces Higher Risk
Certain factors can tip the risk-benefit calculation. Women, particularly those who have had vaginal deliveries, may already have some sphincter weakness, making additional muscle division riskier for continence. Older patients and those with pre-existing bowel conditions also warrant more careful consideration. In these cases, surgeons may opt for a more conservative cut or recommend Botox as a first-line approach instead.
For most patients with a chronic fissure that hasn’t responded to topical treatments, sphincterotomy offers reliable healing with a small but real risk of minor bowel control changes. The serious complications, permanent incontinence to solid stool, abscess, significant infection, each affect around 1% of patients or fewer.