An anal fissure scar is the fibrous tissue that replaces the original wound when a fissure in the anal canal heals. In clinical practice, scar formation at the fissure site is actually the definition of a healed fissure, and doctors look for it as the primary sign that treatment has worked. But the relationship between anal fissures and scar tissue is not always straightforward. In chronic fissures, scarring can become part of the problem rather than the solution, contributing to stiffness, narrowing, and ongoing symptoms even after the original tear has closed.
What Happens When a Fissure Heals
A typical acute anal fissure is a small tear in the lining of the anal canal, usually caused by passing hard stool. When this tear heals normally, the body patches the wound with scar tissue, much like a cut on your hand would heal. In trials of botulinum toxin for chronic fissures, researchers defined treatment success specifically as the formation of a scar at the fissure site. In one randomized trial, 11 of 15 treated patients had healed fissures at two months, with healing confirmed by the presence of a scar where the fissure had been.1PubMed. A comparison of botulinum toxin and saline for the treatment of chronic anal fissure A separate trial comparing two botulinum toxin formulations found that roughly 46 to 47 out of 50 patients in each group had a healing scar at two months.2PubMed. Botulinum neurotoxin to treat chronic anal fissure: results of a randomized “Botox vs. Dysport” controlled trial
So when your doctor says a fissure has “scarred over,” that is good news. The scar means the epithelial lining has been replaced by connective tissue and the open wound has closed. The trouble begins when that process stalls, goes wrong, or produces too much fibrous tissue.
Why Chronic Fissures Develop Problematic Scarring
Most acute fissures heal within a few weeks with conservative measures like fiber, fluids, and stool softeners. When a fissure fails to heal and persists beyond about six to eight weeks, it is classified as chronic. At this stage, the wound bed undergoes changes that make normal healing progressively harder. The edges of the fissure become thickened with fibrosis, and two characteristic scar-related structures often develop: a sentinel skin tag at the outer margin of the fissure, and a hypertrophied anal papilla at the inner margin.
Recent histological research has shed light on why chronic fissures get stuck in this cycle. A study comparing tissue samples from chronic fissure patients with healthy controls found that blood vessel density in the fissure bed was dramatically lower in chronic fissures. Tissue inflammation and thickening of the skin layer were present in about three-quarters of chronic fissure patients, and there was a strong inverse relationship between blood vessel density and the degree of fibrosis.3Reports of Vinnytsia National Medical University. Ischemic component in the pathogenesis of chronic anal fissure: microcirculatory remodeling and fibrosis In plain terms, the area around a chronic fissure has poor blood supply, and where blood flow is worst, scar tissue builds up the most. This creates a feedback loop: the scar tissue itself is poorly vascularized, which starves the wound of the oxygen and nutrients it needs to complete healing, which leads to more scarring.
Compounding this, the internal anal sphincter muscle beneath the fissure tends to go into persistent spasm in chronic cases, further reducing blood flow to the area.4PubMed Central. Concepts in pathogenesis and treatment of chronic anal fissure–a review of the literature This is why so many treatments for chronic fissures focus on relaxing the sphincter: not to fix the tear directly, but to restore blood flow so the body’s own repair mechanisms can work.
Sentinel Tags, Papillae, and the Scar Tissue You Can Feel
If you have had a chronic anal fissure, you may notice a small bump or flap of skin near the anus even after the fissure itself has healed. This is usually a sentinel skin tag, a mound of fibrotic tissue that formed at the external edge of the fissure during the chronic phase. At the internal edge, inside the anal canal, a hypertrophied anal papilla can develop. Both are essentially scar tissue byproducts of the chronic fissure process.
These structures are not dangerous, but they can be annoying. A study comparing outcomes in patients who had sentinel tags and papillae removed during fissure surgery versus those who had sphincterotomy alone (leaving the tags in place) found substantially higher satisfaction rates when the extra tissue was removed. Patients who had the tags and papillae excised reported significantly less pain during bowel movements, less foreign-body sensation, and less itching or wetness around the anus.5PubMed Central. Hypertrophied anal papillae and fibrous anal polyps, should they be removed during anal fissure surgery? Satisfaction was about 89% in the group that had the tissue removed, compared with 64% in the group that did not.
If you still have a persistent bump after your fissure has healed, it is worth mentioning to your doctor. Sentinel tags are harmless, but they can trap moisture and small amounts of stool, which leads to irritation. Removal is a minor procedure and can meaningfully improve comfort.
When Scarring Goes Too Far: Anal Stenosis
The most serious complication of excessive anal scar tissue is stenosis, a narrowing of the anal canal. This happens when rigid, non-elastic fibrous scar tissue replaces the normal flexible tissue of the canal. Stenosis can develop from a chronic fissure itself, but it is more commonly a complication of anal surgery, particularly hemorrhoidectomy. The incidence is estimated at around 5%, and symptoms include severe constipation, a sensation of blockage, and pain that does not improve with stool softeners or dietary changes.6PubMed Central. Anal Repair and Diamond Flap in Patient with Moderate Anal Stenosis After Open Hemorrhoidectomy Surgery: A Case Report
Anal stenosis is essentially a problem of too much scar tissue in the wrong configuration. Where a healthy anal canal stretches to accommodate stool, a stenotic canal is constricted by a ring of fibrosis that does not give. Mild cases can sometimes be managed with gentle dilation, but moderate to severe stenosis typically requires surgical correction with some form of tissue flap to replace the scarred lining with healthy, pliable skin.
Surgical Approaches to Scar Tissue Removal
When a chronic fissure has built up significant scar tissue and is not responding to medical treatment, surgery may involve directly removing the scarred wound bed. In a fissurectomy, the surgeon excises the fissure itself along with the surrounding fibrotic tissue, cutting down to healthy tissue at the level of the internal sphincter. Any sentinel tags or piles are also removed. The goal is to create a fresh, clean wound without scar tissue, which is then allowed to heal on its own.7PubMed Central. Fissurectomy Versus Lateral Internal Sphincterotomy in the Treatment of Chronic Anal Fissure: A Randomized Control Trial The logic is simple: the old scar was poorly vascularized and stuck in a non-healing cycle, so removing it gives the body a second chance at proper wound repair.
For larger defects or cases where the wound bed is too big to heal well on its own, surgeons can cover the excision site with an advancement flap. One common technique involves raising a U-shaped or rectangular flap of skin from nearby and sliding it into the anal canal to cover the wound. The flap brings its own blood supply, which overcomes the ischemia problem that plagued the original fissure.8PubMed Central. Anocutaneous advancement flap provides a quicker cure than fissurectomy in surgical treatment for chronic anal fissure—a retrospective, observational study Another variation, the “house” advancement flap, combines features of different flap designs and has been used for a range of situations where the anal lining needs replacement, with high success and satisfaction rates.9PubMed. Use of “house” advancement flap in anorectal diseases
These flap procedures are particularly useful in anal stenosis, where the scar tissue needs to be replaced rather than simply left to regrow. The choice between a simple fissurectomy and a flap-based repair depends on the extent of scarring, the flexibility of the remaining anal lining, and whether the patient has had previous surgeries in the area.
The Keyhole Deformity Question
One concern that comes up frequently in discussions of anal fissure surgery is the keyhole deformity, a groove-shaped defect in the anal canal at the site where a sphincterotomy was performed. The worry is that this groove prevents the anus from closing completely, leading to minor leakage of mucus or stool. In reality, while the keyhole deformity does exist as a recognized finding, research suggests it occurs only rarely after fissure surgery and is often not associated with incontinence when it does appear.10PubMed. Keyhole deformity. Fact and fiction This is one of those surgical complications that looms larger in patient anxiety than in actual clinical outcomes.
Medical Treatments and How They Affect Scarring
Most first-line treatments for chronic anal fissures work by relaxing the internal sphincter muscle, which improves blood flow to the fissure bed and allows healing (and therefore scar formation) to proceed. The two most studied options are topical nitroglycerin ointment and botulinum toxin injections. Nitroglycerin healing rates range from about 30% to 86% across studies, though headaches are a common side effect. Botulinum toxin injections show comparable healing rates of roughly 43% to 96%.11PubMed Central. Concepts in pathogenesis and treatment of chronic anal fissure–a review of the literature Calcium channel blockers like diltiazem are another option, and a study of topical diltiazem found that patients whose fissures healed reported meaningful improvements in pain, energy levels, and mental health.12PubMed Central. Quality of life in patients with chronic anal fissure after topical treatment with diltiazem
The wide ranges in healing rates reflect the reality that chronic fissures are stubborn. Some patients respond quickly to medical therapy, form a healthy scar, and move on. Others cycle through multiple treatments before achieving healing, and a meaningful minority will eventually need surgery.
Pelvic Floor Therapy and Scar Mobilization
An underappreciated approach to anal fissure management is pelvic floor physical therapy. Chronic fissures are closely associated with increased pelvic floor muscle tension, and there is growing evidence that addressing this directly can help. A randomized controlled trial found that patients who received pelvic floor physical therapy had a fissure healing rate of about 56%, compared with roughly 21% in the control group. They also showed significant improvements in pain, reduced muscle tension, and better coordination of the muscles involved in defecation.13PubMed Central. Pelvic floor physical therapy in patients with chronic anal fissure: a randomized controlled trial
After surgery or childbirth-related anal injury, physical therapists also work directly on scar tissue through manual techniques. Postpartum pelvic floor rehabilitation, for example, includes evaluation of laceration scar tissue and individualized manual therapy that incorporates self-massage of the perineal area to improve tissue flexibility.14PubMed Central. Evaluation of Postpartum Pelvic Floor Physical Therapy on Obstetrical Anal Sphincter Injury: A Randomized Controlled Trial The principle applies to anal fissure scars as well: scar tissue that is stiff and restrictive can sometimes be made more pliable through sustained, gentle mobilization. This is not a quick fix, but for people dealing with persistent tightness or discomfort around a healed fissure, it is an option worth exploring with a specialist.
Postoperative Wound Care
After fissure surgery, the wound typically heals by secondary intention, meaning it fills in gradually from the bottom up rather than being stitched closed (advancement flaps being the exception). During this period, how you care for the wound can influence the quality of the eventual scar. Warm water sitz baths are commonly recommended, and a randomized study of patients after sphincterotomy found that the sitz bath group experienced significantly less anal burning compared with the control group.15PubMed. Effects of warm water sitz bath on symptoms in post-anal sphincterotomy in chronic anal fissure–a randomized and controlled study The baths did not dramatically change overall pain scores at one week, but they improved comfort and the overall recovery experience.
Keeping the wound clean, maintaining soft stools to avoid re-tearing, and following up with your surgeon to ensure the wound is granulating properly are all standard parts of postoperative care. The healing period can take several weeks, and the scar that forms during this time will continue to mature and soften over the following months, as scar tissue does everywhere in the body.
When a Nonhealing “Scar” Needs a Closer Look
Not every chronic wound at the anus is a garden-variety fissure. Fissures that sit in unusual positions (off the midline), fissures with hardened or ulcerated edges, and fissures that simply refuse to heal despite appropriate treatment should raise a flag. A case series documented three patients with squamous cell carcinoma of the anus who were initially misdiagnosed with benign chronic anal fissure. The authors emphasized that nonhealing fissures, fissures in atypical locations, and those with indurated or ulcerated tags warrant biopsy to rule out cancer.16PubMed Central. A Case Series of Anal Carcinoma Misdiagnosed as Idiopathic Chronic Anal Fissure
Crohn’s disease is another condition that can produce anal fissures with unusual scarring patterns. Perianal Crohn’s disease can cause fissures, ulcers, skin tags, and anal strictures, and these manifestations often significantly affect quality of life through pain, drainage, and difficulty with hygiene.17PubMed Central. Nonfistulizing Perianal Crohn’s Disease If you have multiple fissures, fissures that keep recurring in different locations, or associated symptoms like chronic diarrhea or abdominal pain, Crohn’s disease should be on the list of possibilities to discuss with your doctor.
Chronic Pain, Central Sensitization, and Scar Sensitivity
Some people continue to experience pain in the anal area even after a fissure has clearly healed and a scar has formed. This can be genuinely confusing: the wound is closed, the tissue looks intact on examination, yet the area remains tender or painful, especially during bowel movements. One explanation is that prolonged pain from a chronic fissure can lead to changes in how the nervous system processes pain signals from the pelvic region. Peripheral inflammation around the fissure site, sustained pelvic floor muscle tension, and ultimately shifts in how the spinal cord and brain handle pain input from the area have all been identified as contributors to persistent anorectal and pelvic pain.18PubMed Central. Anorectal and Pelvic Pain Psychological factors like anxiety around bowel movements can reinforce this cycle.
Scar tissue itself can also be a source of discomfort independent of these nervous system changes. Scars are less elastic than normal tissue, they have different nerve endings, and they can be sensitive to stretching. For someone whose fissure was chronic for months or years before healing, the resulting scar may be thicker and stiffer than what a quickly healed acute fissure would produce. This is another area where pelvic floor physical therapy and scar mobilization techniques can sometimes help.
Platelet-Rich Plasma as an Emerging Option
One newer approach being studied for anal fissures is platelet-rich plasma (PRP), a concentrated preparation made from your own blood that is rich in growth factors involved in tissue repair. A randomized trial of 94 patients with acute and chronic fissures found that adding a single injection of PRP to standard topical treatment produced significantly better outcomes: a healing rate of 96% in the PRP group versus 66% with topical treatment alone at six months, along with substantially lower pain and bleeding rates throughout the follow-up period.19PubMed Central. Platelet-rich plasma improves acute and chronic anal fissure, a randomized control trial The idea is that delivering a concentrated dose of growth factors directly into the poorly vascularized fissure bed can jumpstart the repair process that the body’s diminished local blood supply cannot accomplish on its own. While this is still a relatively new application and needs more research to establish its place in standard practice, the initial results are encouraging for patients who have struggled with nonhealing fissures.