Anal Fissure

An anal fissure is a small tear in the lining of the anus that causes sharp pain and bleeding during bowel movements. While this common condition affects people of all ages, most cases heal with simple self-care measures within a few weeks.

Table of contents

• What is an anal fissure?
• Symptoms and signs
• Causes and risk factors
• How anal fissures are diagnosed
• Treatment options
• Prevention
• Complications

What is an anal fissure?

An anal fissure is a crack or tear in the thin, moist tissue that lines the anal canal (the opening at the end of the digestive tract where stool exits the body)^[1][2]. This tear occurs in the delicate skin called the anoderm, which is thinner and more sensitive than regular skin, making it easier to tear^[1].

Anal fissures are very common, especially in young infants and people under 40 years of age^[1][3]. About half of people with anal fissures develop them before they turn 40^[1].

Fissures are classified based on how long they have been present. Acute fissures are recent tears that have lasted less than 6 weeks and often look like a simple paper cut^[7][4]. Chronic fissures persist for more than 6 to 8 weeks and may have deeper tears with swelling and scar tissue present^[4][7]. Chronic fissures may also develop a small lump of skin near the tear, called a sentinel pile or skin tag, and extra tissue just inside the anal canal, called a hypertrophied papilla^[4].

Most anal fissures occur in the posterior midline (back portion of the anus, toward the tailbone), with about 85-90% found in this location. About 10-15% occur in the anterior midline (front portion, near the perineum)^[4]. Fissures located elsewhere should raise suspicion for other underlying diseases^[4][7].

Symptoms and signs

The most common symptom of an anal fissure is severe, sharp pain during bowel movements^[1][2][3]. About 90% of people with fissures experience pain, though not everyone does^[1]. The pain is often described as sharp, tearing, cutting, or burning^[1][4]. Many patients say their bowel movements feel like “shards of glass” or “razor blades”^[14].

Pain typically occurs during defecation and can last from several minutes to several hours afterward^[1][2][3]. Some people find that the pain radiates to their buttocks, upper thighs, or lower back^[1]. Between bowel movements, patients are often relatively symptom-free^[4].

Other common symptoms include:

• Bright red blood on toilet paper or in the toilet after a bowel movement^[1][2][3]
• Burning or itching during or after bowel movements^[1][3]
• Anal muscle spasms^[1][2]
• A visible crack or tear in the skin around the anus^[2]
• A small lump or skin tag near the fissure^[1][2]

Many patients become fearful of having bowel movements and may try to avoid defecation because of the severe pain^[4]. This avoidance can lead to constipation, which further worsens the condition.

Anal fissures are often confused with hemorrhoids because both conditions can cause rectal bleeding, anal pain, and anal itching. However, hemorrhoids don’t always cause pain, while 90% of fissures do. The pain from a fissure usually occurs in episodes related to bowel movements, while hemorrhoid pain can be constant^[1].

Causes and risk factors

Anal fissures are usually caused by trauma or injury to the inner lining of the anus^[4][1]. The most common cause is stretching of the anal mucosa beyond its normal capacity, especially from straining to pass hard or large stools^[2][5].

The anatomy of the anus makes it vulnerable to tearing. In the upper portion of the anal canal, where fissures usually occur, the anus is lined with soft mucosa, which is thinner and more delicate than normal skin. This is especially true for babies, who often get anal fissures^[1]. The anoderm is more adherent to underlying tissue in the posterior midline, and blood supply to this area is significantly lower, which contributes to fissure development^[15].

The anus is surrounded by two circular muscles called anal sphincters that help control bowel movements. When these muscles are too tight, they can add tension to the anal lining, making it easier to tear and reducing blood flow to the tissues^[1]. The injury creates severe pain, which results in anal sphincter spasm and increases muscle pressure. This increased pressure further decreases blood flow to the area, impairing healing and creating a vicious cycle^[4][14].

Primary causes of anal fissures include:

• Chronic constipation and straining to pass stool^[1][3]
• Passing hard, dry, or large stools^[2][5]
• Chronic diarrhea or prolonged loose stools^[1][2][5]
• Childbirth trauma in women^[1][3][5]
• Anal sex or penetration^[1][5]
• Obstructed defecation syndrome^[1]
• Infant dyschezia (difficulty with bowel movements in infants)^[1]

Other contributing conditions include:

• Prior anal surgery^[1]
• Sexually transmitted infections such as syphilis, herpes, chlamydia, or human papilloma virus^[1][3][5]
• Inflammatory bowel disease, including Crohn’s disease and ulcerative colitis^[1][3][5]
• Anal cancer^[1]
• Tuberculosis^[1][5]
• Diaper rash in infants^[1]
• Decreased blood flow to the area in older adults^[2]

Anal fissures are more common in people aged 15 to 40 and in young children^[3]. They affect both men and women equally^[4]. In infants, anal fissures are very common, affecting around 8 out of 10 babies^[8].

How anal fissures are diagnosed

Diagnosis of an anal fissure is primarily based on your medical history, symptoms, and a physical examination^[7][10]. Your doctor will ask about your symptoms and perform a gentle visual inspection of the anal area^[3][10]. Often the tear is visible during this examination^[10].

External anal fissures on the anal verge can be diagnosed by visual inspection. A more recent acute fissure looks like a fresh tear, similar to a paper cut. A chronic anal fissure has a deeper tear and may show swelling, scar tissue, sentinel piles, or hypertrophied papillae^[10][7].

In some cases, your doctor may perform a gentle digital rectal examination by inserting a gloved finger through the anal sphincter to feel for the fissure^[7]. However, narrow fissures might not be felt during this exam^[7].

If the examination causes significant pain or if your doctor is uncertain about the diagnosis, you may be referred to a specialist for an examination under general anaesthetic (where you’ll be asleep and won’t feel anything)^[3].

Additional tests may be recommended if:

• The fissure is located off to the side rather than in the front or back midline^[10]
• There are multiple fissures^[4]
• The fissure is not healing with proper treatment^[4]
• You have other symptoms such as stomach pain or diarrhea^[10]
• You are older than 45 or have risk factors for colon cancer^[10]

These additional tests may include:

• Anoscopy – a tubular device is inserted into the anus to see the rectum and anus^[10]
• Flexible sigmoidoscopy – a thin, flexible tube with a camera is inserted to inspect the lower portion of the colon^[10]
• Colonoscopy – a flexible tube is inserted to inspect the entire colon^[10]

These tests help rule out other conditions with similar symptoms and check for underlying diseases that may be causing the fissure.

Treatment options

The majority of anal fissures, especially acute ones, heal on their own without surgery^[4][2]. More than 80% of acute anal fissures resolve with conservative treatment^[12]. About half of cases heal by themselves with proper self-care and avoidance of constipation^[8].

Conservative treatment

Initial treatment focuses on breaking the cycle of hard bowel movements, pain, and worsening constipation^[12]. Conservative treatment usually works within 6 to 8 weeks^[9].

First-line treatments include:

• Dietary changes – Eat a high-fiber diet with fruits, vegetables, beans, and whole grains (25-35 grams of fiber per day)^[4][3]. This helps soften stools and makes them easier to pass.
• Fiber supplements – Over-the-counter fiber supplements can help increase fiber intake^[4][3]
• Hydration – Drink plenty of water to keep stools soft^[3][4]
• Stool softeners – Over-the-counter stool softeners may be necessary^[4]
• Sitz baths – Sit in 8 to 10 centimeters (3 to 4 inches) of warm water for 10-20 minutes several times a day, especially after bowel movements. This soothes pain and helps relax the anal muscles^[4][3]
• Pain relief – Take paracetamol or ibuprofen to help with pain^[3]. Topical anesthetics like lidocaine can be used for anal pain^[4]

Avoid narcotic pain medications, as they promote constipation^[4]. Do not use over-the-counter ointments or creams without talking to your doctor, as some may not help^[19].

It’s important to respond to the urge to have a bowel movement and not delay^[3][19]. Do not sit on the toilet for more than 10 minutes^[19]. Use baby wipes or medicated pads instead of toilet paper to clean after bowel movements, as these are gentler on the area^[19].

Medical treatment

If conservative treatment doesn’t work or if you have a chronic fissure, your doctor may prescribe medications^[3][4]:

• Laxatives – To help with constipation^[3]
• Antispasmodic medicines – Such as Buscopan or mebeverine to help with pain after bowel movements^[3]
• Nitroglycerin ointment – Applied directly to the internal sphincter to relax the muscle, relieve pain, and increase blood flow to the area. This is FDA-approved for moderate-to-severe pain associated with anal fissures^[12][4]. Common side effects include headache and dizziness^[12].
• Calcium channel blockers – Topical medications that help relax the sphincter muscle^[7]
• Healing cream – Applied to the anus to promote healing, which may need to be used for up to 8 weeks^[3]

Surgical treatment

Surgery may be recommended if medical treatments fail, if you have a chronic fissure that won’t heal, or if fissures keep recurring^[3][4][12]. The main surgical options include:

• Botox injections – An injection into the anus to help the muscles relax so the tear can heal^[3][7]
• Lateral internal sphincterotomy – A small cut is made in the internal anal sphincter muscle to reduce tension and improve blood flow, allowing the tear to heal. This is the preferred surgical option for chronic fissures^[3][15]. It carries a small risk of temporary incontinence^[7]

These procedures are done under general anaesthetic, so you’ll be asleep and won’t feel anything^[3].

Prevention

You can help prevent anal fissures by following these measures:

• Prevent constipation – Include plenty of fiber in your diet (fruits, vegetables, beans, whole grains) and drink lots of water^[5][3]
• Avoid straining – Don’t strain when having a bowel movement^[5][3]
• Treat diarrhea promptly – Quick treatment of diarrhea may reduce anal strain^[5]
• Exercise regularly – Get some exercise every day, building up to at least 2½ hours of moderate to vigorous exercise per week^[19]
• Maintain anal hygiene – Keep your bottom clean and dry using gentle cleaning methods^[3][5]
• Don’t ignore the urge – Go to the toilet when you feel the need to have a bowel movement^[3][19]
• Stay on a high-fiber diet – If you’ve had a fissure that healed, staying on a high-fiber diet can reduce recurrence rates from 30-70% down to 15-20%^[12]

Complications

Many anal fissures heal by themselves in a few weeks, but complications can develop when they don’t^[1]. When a fissure fails to heal within 8 weeks, it becomes a chronic anal fissure^[10].

Chronic fissures create a vicious cycle. Pain and muscle clenching cause the anal muscles to tighten and spasm. Muscle tension and spasms pull the fissure apart and reduce blood flow to the tissues, making it harder to heal and leaving a persistent wound^[1][4].

Possible complications of anal fissures include:

• Chronic anal fissure – The tear fails to heal. Over time, extensive scar tissue can form at the site of the fissure (sentinel pile)^[8]
• Anal fistulas – Abnormal tunnels that connect the anal canal to surrounding organs, usually other parts of the bowel^[8]
• Anal stenosis – The anal canal becomes abnormally narrowed due to spasm of the anal sphincter or scar tissue contraction^[8]

Anal fissures themselves are not associated with more serious diseases such as bowel cancer, although anal cancer may mimic an anal fissure^[8]. If you have blood mixed in with your stool rather than just on the surface, talk to your doctor^[19].