Anal Bleeding: Causes, Symptoms, and Treatment Options

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Medically Reviewed by Dr. Sulaiman Bin Yusof

MbChB (Sheffield)

M.Med (Surgery)

FRCSEd (General Surgery)

Anal bleeding is a concerning symptom for many, often associated with discomfort or visible blood in stool or on toilet paper. Recognising the common causes, associated symptoms, and available treatment options can help individuals take appropriate steps for their health. This article provides a thorough overview, addressing the various reasons for anal bleeding, the symptoms that accompany it, and when to seek specialised care from a colorectal surgeon.

What Causes Anal Bleeding?

There are several potential reasons for anal bleeding, ranging from benign to more serious conditions. Some of the common causes include:

Haemorrhoids

Haemorrhoids are swollen blood vessels in the rectum or anus that develop due to increased pressure from straining during bowel movements, prolonged sitting, or pregnancy. When these blood vessels enlarge, they may rupture, leading to bright red bleeding, often noticeable on toilet paper or in the toilet bowl. Internal haemorrhoids form inside the rectum, while external haemorrhoids develop around the anus.

Anal Fissures

Anal fissures are small tears in the lining of the anus, often caused by passing large or hard stools or from straining. These tears expose underlying blood vessels, which can lead to minor bleeding. Anal fissures are a common cause of bleeding from the anus, especially in individuals who experience constipation or have difficulty passing stool.

Diverticular Disease

Diverticular disease involves the formation of small pouches, called diverticula, in the walls of the colon. They typically develop in weakened areas of the colon lining, often due to ageing or dietary factors. When diverticula become inflamed (diverticulitis) or develop small tears, blood vessels within them may rupture, resulting in bleeding. Blood from diverticular bleeding can range in colour from dark red to bright red, depending on where it originates in the colon.

Inflammatory Bowel Disease (IBD)

Inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis, cause long-term inflammation in different parts of the digestive tract. This chronic inflammation weakens the intestinal lining, making it more prone to bleeding. During disease flare-ups, ulcers or sores may form in the colon, further increasing the risk of bleeding.

Colorectal Polyps and Cancer

Polyps are small growths in the colon or rectum. While many are benign, some can bleed and may develop into cancer over time. Colorectal cancer is a serious condition that often presents with blood in the stool, along with changes in bowel habits and unexplained weight loss.

Other Causes

Other possible causes of anal bleeding include rectal ulcers, proctitis (inflammation of the rectum), and infections. Rectal ulcers may develop due to chronic constipation or other underlying conditions, leading to tissue breakdown and bleeding. Proctitis, which can result from infections or autoimmune conditions, causes inflammation and irritation in the rectum, making the area more likely to bleed.

Symptoms of Anal Bleeding

Recognising associated symptoms can aid in determining the cause of anal bleeding. Key symptoms to note include:

Colour of Blood

Bright red blood is commonly associated with haemorrhoids or anal fissures. This type of bleeding typically indicates a problem near the anus, such as irritated or torn blood vessels, and can be painless or cause minor discomfort.

Dark-Coloured or Tarry Stool

Dark or tarry stools can indicate bleeding higher up in the digestive tract, such as in the colon. This type of stool frequently has a distinct odour and is associated with conditions such as diverticular disease or, in some cases, colorectal cancer.

Pain During Bowel Movements

Pain during bowel movements commonly occurs with anal fissures or haemorrhoids. Anal fissures can cause sharp pain due to small tears in the lining, while haemorrhoids may feel irritated when swollen vessels are compressed during bowel movements.

Abdominal Pain or Cramping

Abdominal pain, particularly with anal bleeding, can indicate intestine-related conditions such as inflammatory bowel disease (IBD) or diverticular disease. This pain can vary in location and intensity and may require further investigation.

Changes in Bowel Habits

Anal bleeding may be accompanied by persistent symptoms such as diarrhoea, constipation, or a frequent urge to go without much stool. IBD and colorectal cancer are two conditions that may cause these changes in bowel habits.

Unexplained Weight Loss or Fatigue

Unexpected weight loss or constant fatigue, combined with anal bleeding, may indicate a more serious condition, such as colorectal cancer. These symptoms are often caused by the body’s reaction to an underlying illness and may necessitate medical attention.

Diagnosis Methods for Anal Bleeding

Determining the cause of anal bleeding typically involves several steps, starting with a detailed medical history and proceeding to specific diagnostic tests.

Medical History and Physical Examination

A doctor will typically start by reviewing the patient’s medical history, including any family history of digestive disorders or colorectal cancer. A physical examination, which may include a digital rectal exam, allows the doctor to check for haemorrhoids, fissures, or other abnormalities in the rectum.

Stool Tests 

Faecal occult blood tests (FOBT) and faecal immunochemical tests (FIT) are commonly used to detect hidden blood in the stool. These tests can detect bleeding in the digestive tract even when it is not visible to the naked eye.

Endoscopic Procedures 

Colonoscopy and flexible sigmoidoscopy are common endoscopic procedures used to examine the colon and rectum. A colonoscopy shows the entire colon, whereas a sigmoidoscopy shows only the lower part of the colon. If abnormalities, such as polyps or inflammation, are discovered, a biopsy may be performed to further analyse the tissue.

Imaging Tests  

Imaging tests, such as CT colonography (virtual colonoscopy), can provide detailed images of the colon and rectum. These tests may be recommended if endoscopy is not possible or as a complementary diagnostic tool to help assess the extent of bleeding and detect any structural issues.

Blood Tests  

Blood tests can be used to detect anaemia, which can be caused by chronic blood loss from certain digestive conditions. These tests may also reveal general information about the patient’s overall health.

Treatment Options for Anal Bleeding

Treatment for anal bleeding depends on the underlying cause. Options include both non-surgical and surgical approaches.

Non-Surgical Treatment

Medication

Topical creams and ointments can help relieve symptoms of haemorrhoids and anal fissures by soothing inflamed tissue and reducing swelling and pain. For conditions like inflammatory bowel disease (IBD) or infections, anti-inflammatory drugs or antibiotics work to control inflammation or eliminate infection, which can reduce bleeding over time.

Minimally Invasive Procedures  

More persistent haemorrhoids are treated with minimally invasive procedures such as rubber band ligation (placing a small band around a haemorrhoid to cut off blood flow) or sclerotherapy (injecting a solution to shrink the haemorrhoid). These procedures reduce the size of haemorrhoids, lowering the risk of further bleeding.

Surgical Treatment

Haemorrhoidectomy  

A haemorrhoidectomy involves surgically removing haemorrhoid tissue, providing a longer-term solution for severe or recurring haemorrhoids. This procedure eliminates the source of bleeding, especially when non-surgical methods have not been effective.

Sphincterotomy  

In cases of chronic anal fissures, a sphincterotomy relieves pressure on the anal sphincter muscle, allowing the fissure to heal. This reduces pain and bleeding by promoting recovery of the damaged tissue in the anal lining.

Colectomy or Bowel Resection  

For serious conditions like diverticular disease or colorectal cancer, a colectomy (removal of part of the colon) or bowel resection may be necessary. This surgery removes the affected section of the colon, addressing the source of bleeding and reducing the risk of future complications.

Abscess Drainage or Fistula Repair 

If an abscess or fistula is causing bleeding, a minor surgical procedure can drain the abscess or repair the fistula. This treatment addresses infection and inflammation in the affected area, which can help stop bleeding and promote healing.

When to See a Colorectal Surgeon

Individuals experiencing persistent or unexplained anal bleeding should consider consulting a colorectal surgeon, particularly if they observe additional symptoms like unexplained weight loss, changes in bowel habits, or severe pain. Early diagnosis and intervention are key to managing and treating the underlying cause of anal bleeding effectively.

Conclusion

Anal bleeding can arise from a range of conditions, each requiring careful assessment to determine the appropriate treatment approach. While some causes are minor and easily managed, others may necessitate medical intervention to prevent complications. Recognising changes in bowel habits, visible blood, or other symptoms is necessary to ensure timely care.

If you are experiencing persistent or unexplained anal bleeding, schedule a consultation for a comprehensive evaluation and personalised treatment plan.