Anal Fissures

What is an anal fissure?

An anal fissure is a small tear or split in the thin lining of the anus, the opening through which stool passes. It is a common condition that can cause sharp pain and bleeding during or after bowel movements.

Fissures often occur when the anal canal is stretched beyond its normal capacity, usually due to passing hard or large stools. They may also result from persistent diarrhoea, straining with constipation, inflammatory bowel disease or trauma to the area.

Although anal fissures are not usually serious, they can be extremely uncomfortable and distressing. In most cases, they heal within a few weeks with simple measures such as stool softening and topical treatments. However, some fissures may become chronic, requiring medical procedures or surgery to promote healing.

What causes an anal fissure?

Anal fissures usually develop when the lining of the anus is overstretched or injured. The most common cause is the passage of hard, dry or bulky stools during constipation, which puts excessive pressure on the anal canal.

Other causes and contributing factors include:

• Persistent diarrhoea — frequent loose stools can irritate and damage the anal lining.

• Straining during bowel movements — often due to chronic constipation or difficulty passing stool.

• Childbirth — fissures are relatively common in women after vaginal delivery.

• Anal trauma — from insertion of foreign objects or anal intercourse.

• Inflammatory bowel disease (IBD) — conditions such as Crohn’s disease can increase susceptibility to fissures.

• Reduced blood supply — poor circulation to the anal area, more common in older adults, can slow healing and make fissures more likely.

While many fissures heal on their own, some persist or recur, often because of ongoing constipation, repeated straining or underlying medical conditions.

What are the symptoms of an anal fissure?

Anal fissures usually cause noticeable discomfort, especially during and after bowel movements. The symptoms may vary in severity depending on whether the fissure is recent (acute) or long-standing (chronic).

Common symptoms include:

• Sharp pain during bowel movements — often described as tearing or cutting, which may last for minutes to hours afterwards.

• Bright red blood on the stool or toilet paper — bleeding is usually small in amount and seen separately from the stool.

• Visible tear or crack — sometimes seen on inspection of the anal opening.

• Itching or irritation around the anus — caused by the fissure itself or from moisture and discharge.

• Spasm of the anal sphincter muscle — a tightening that worsens pain and interferes with healing.

Chronic fissures may also show a small skin tag near the tear or a thickened area inside the anal canal.

How can I tell the difference between a haemorrhoid and an anal fissure?

Anal fissures and haemorrhoids are two of the most common causes of anal pain and bleeding, but they affect the body differently.

An anal fissure is a small tear in the delicate lining of the anus. It causes sharp, cutting pain during and after bowel movements and may lead to a small amount of bright red bleeding. A haemorrhoid, by contrast, is a swollen blood vessel inside or around the anus that often causes itching, swelling and a dull ache. Haemorrhoids may bleed more noticeably, and in some cases, a lump can be felt.

Because both conditions share overlapping symptoms, professional evaluation is important to confirm the diagnosis and rule out more serious conditions.

When to seek medical help

While both haemorrhoids and anal fissures can often be managed with simple measures, you should see a doctor promptly if you experience any of the following:

• Persistent or severe pain that does not improve with self-care.
• Heavy or recurrent rectal bleeding.
• A lump around the anus that is painful, swollen or increasing in size.
• Bleeding accompanied by unexplained weight loss, changes in bowel habits or abdominal pain.
• Symptoms lasting more than two weeks despite home treatment.

Prompt medical assessment ensures the correct diagnosis, rules out more serious conditions such as colorectal cancer, and allows timely treatment for lasting relief.

What are the possible complications of an anal fissure?

Most anal fissures heal on their own or with simple treatments, but in some cases, they may lead to complications, especially if left untreated or if the underlying cause persists.

• Chronic fissure —  a fissure that fails to heal after six to eight weeks may become chronic, with harder edges and reduced blood supply, making recovery more difficult.

• Persistent pain and bleeding — ongoing discomfort and repeated bleeding during bowel movements can affect daily life and emotional well-being.

• Anal sphincter spasm — muscle tightness around the anus may become prolonged, further reducing blood flow and preventing healing.

• Skin tag or sentinel pile — a small lump of skin may form near the fissure in chronic cases.

• Recurrent fissures — some people develop fissures repeatedly, particularly if constipation or diarrhoea continues.

• Rare complications — in severe or untreated cases, infection or abscess formation may occur, though this is uncommon.

While these complications are not usually life-threatening, they can be distressing and significantly affect quality of life. Seeking medical care helps prevent fissures from becoming long-standing problems.

Who is at risk of developing an anal fissure in Singapore?

Anal fissures can affect people of any age, but certain factors increase the likelihood of developing them:

• Chronic constipation — passing hard or bulky stools is the leading cause.

• Persistent diarrhoea — frequent loose stools can irritate and injure the anal lining.

• Straining during bowel movements — often due to constipation or difficulty emptying the bowel.

• Childbirth — women are at increased risk of fissures following vaginal delivery.

• Inflammatory bowel disease (IBD) — conditions such as Crohn’s disease raise the risk of fissures.

• Older adults — reduced blood supply to the anorectal area can slow healing and predispose to fissures.

• Anal trauma — from insertion of foreign objects or anal intercourse.

Understanding these risk factors helps in both prevention and early treatment, reducing the chance of fissures becoming chronic.

How can I prevent anal fissures?

Although not all anal fissures can be avoided, adopting healthy bowel habits and lifestyle measures greatly reduces the risk of developing them or prevents recurrence after treatment.

• Maintain soft, regular stools — eat a diet rich in fibre from fruits, vegetables and wholegrains, and drink plenty of fluids to avoid constipation.

• Avoid straining — do not sit on the toilet for long periods or force bowel movements, as this puts extra pressure on the anal lining.

• Respond promptly to the urge to pass stool — holding it in can lead to harder, bulkier stools that increase the risk of tears.

• Manage diarrhoea — seek treatment for frequent loose stools, as ongoing irritation of the anus can also cause fissures.

• Stay active — regular physical activity helps keep the bowels moving normally and reduces constipation.

• During pregnancy and after childbirth — pay extra attention to hydration, diet and gentle stool-softening measures, as women are more prone to fissures at this time.

By protecting the anal lining and keeping bowel movements comfortable, these steps not only prevent fissures but also support overall bowel health.

How are anal fissures diagnosed?

Diagnosis of an anal fissure is usually straightforward and based on a doctor’s assessment.

• Medical history — the doctor will ask about symptoms such as pain, bleeding or difficulty with bowel movements, as well as bowel habits, diet and use of medications.

• Physical examination — a gentle inspection of the anal region often reveals the tear. In acute fissures, this may appear as a small split in the lining; in chronic fissures, skin tags or thickened tissue may also be present.

• Digital rectal examination — this is sometimes avoided if the fissure is very painful, but when tolerated, it helps assess muscle tone and rule out other conditions.

• Additional tests — if symptoms suggest another problem, such as inflammatory bowel disease, infection, or colorectal cancer, further investigations such as sigmoidoscopy or colonoscopy may be arranged.

Most fissures can be diagnosed quickly in the clinic, without the need for extensive testing. The key aim is to confirm the fissure and exclude more serious causes of rectal bleeding.

What are the treatment options for anal fissures? 

Treatment for anal fissures aims to relieve pain, promote healing and prevent recurrence. Most fissures heal with non-surgical measures, but persistent or chronic cases may require medical or surgical treatment.

Conservative management

• Dietary changes — increasing fibre intake, drinking plenty of fluids and avoiding straining help soften stools and reduce trauma.

• Stool softeners or laxatives — these may be prescribed to prevent constipation and ease bowel movements.

• Warm sitz baths — sitting in warm water several times a day relaxes the anal sphincter and promotes healing.

• Topical pain relief — anaesthetic creams can reduce discomfort during bowel movements.

Medical therapy

• Topical nitroglycerin or calcium channel blockers — these creams relax the anal sphincter, improve blood flow and support healing.

• Botulinum toxin (Botox) injection — temporarily relaxes the anal sphincter, reducing spasm and allowing the fissure to heal.

Surgical treatment

When fissures do not respond to other therapies, surgery may be considered:

• Lateral internal sphincterotomy — the most common operation, involving a small cut in the anal sphincter muscle to reduce tension and encourage healing.

• Advancement flap surgery — used in selected cases, where healthy tissue is used to cover the fissure and promote repair.

With proper treatment, most anal fissures heal completely. Addressing underlying causes such as constipation or diarrhoea is important to prevent recurrence.

Recovery and outlook after anal fissures

Most anal fissures heal within a few weeks when treated early with dietary changes, stool softeners and topical medicines. Acute fissures often improve quickly once bowel movements become soft and less painful. Warm sitz baths and simple self-care measures also speed recovery.

Chronic fissures may take longer to heal and often require prescription creams, Botox injections, or minor surgery. Surgical treatment, especially lateral internal sphincterotomy, has a high success rate, with most patients experiencing lasting relief and very low recurrence.

Although anal fissures can be painful and distressing, they are rarely dangerous. With the right treatment and prevention strategies, such as maintaining good bowel habits and avoiding straining, the outlook is excellent for most patients.

Summary 

Anal fissures are small but painful tears in the lining of the anus, most often caused by constipation, straining or persistent diarrhoea. They can lead to sharp pain, bleeding and discomfort, but in most cases they heal with simple measures such as dietary changes, stool softeners and topical treatments. Chronic fissures may require medical therapy or minor surgery, both of which are highly effective in promoting healing and preventing recurrence.

If you are experiencing rectal pain or bleeding, schedule a consultation with Tan Siong San Surgery for a thorough evaluation and personalised treatment plan to help you recover quickly and comfortably.