How Does an Anal Fissure Develop?
There is no single specific cause for the development of an anal fissure; rather, a variety of different risk factors are considered causes of anal fissures and will be examined more closely here. An anal fissure means that the sensitive skin in the anal canal is overstretched due to excessive strain and tears. The range of causes for an anal fissure includes stool consistency—due to constipation, hard stools, or diarrhea—straining behavior during bowel movements, as well as low-fiber diet, insufficient fluid intake, and lack of exercise. Also, hemorrhoids or cryptitis and stress can increase the likelihood of an anal fissure.
What Are the Causes of an Anal Fissure?
Anal fissures are often related to stool consistency and straining behavior during bowel movements, but also hemorrhoids or cryptitis, as well as various other pre-existing conditions. Stress and diet, as well as anal intercourse or sexually transmitted diseases, also play a role as possible causes of a tear in the anus. Why an anal fissure develops often cannot be clearly determined. The causes of an anal fissure are diverse, and below we will take a closer look at the possible causes of an anal fissure.
Stool Consistency and Straining Behavior During Bowel Movements
Hard stools can easily injure the sensitive anal mucosa, but excessive straining can also be a cause of anal fissures. Especially the combination of hard stools with intense straining during bowel movements often causes the skin to tear. Causes of regular constipation or hard stools are mainly seen in a low-fiber diet, insufficient fluid intake, and lack of exercise. Besides constipation and hard stools, diarrhea—especially if prolonged—can also promote tears in the anal mucosa.
A fiber-rich diet can help regulate stool consistency and prevent constipation. Fiber ensures that stool remains softer and passes more easily. Foods such as whole grains, fruits, and vegetables should be consumed regularly to promote intestinal health. It is also important to drink enough fluids. Read more here about how to prevent anal fissures.
Additionally, anal fissures occur more frequently during pregnancy and after childbirth. Risk factors here include constipation during pregnancy, a high birth weight of the baby, a long duration of pregnancy, and the pushing efforts during delivery.
Anal Canal Stenosis as a Cause of Anal Fissures
A narrowing of the anal canal can also make bowel movements difficult and lead to increased pressure and friction, which in turn increases the risk of anal fissures. Narrowing of the anal canal, also called anal canal stenosis, can occur for various reasons, such as scarring after surgeries including an anal fissure operation, chronic inflammation, or congenital malformations. This narrowing directly affects bowel movements and increases the risk of anal fissures due to increased pressure during defecation, increased friction, and mechanical stress on the anal mucosa in narrowed passages. Constant strain and stretching of the narrowed anal canal can lead to permanent and chronic overuse and overstretching of the mucosa. As a result, the tissue and mucous membranes in the anal canal become less elastic and can tear more easily, especially during frequent or difficult bowel movements. Blood circulation is often impaired in a narrowed anal canal, which hinders the healing of small tears or micro-injuries. This can cause even small injuries like anal fissures to become chronic or worsen.
Hemorrhoids as a Cause of Anal Fissures
Hemorrhoids are considered a risk factor as a cause of anal fissures. In the case of hemorrhoids, the skin of the anoderm is already correspondingly stressed. The same applies to inflammations in the rectal area, such as anal abscesses or anal fistulas. Poor blood circulation—caused by spasms in the anal area—can also significantly hinder the healing process of anal fissures.
Pre-existing Conditions as Causes and Risk Factors for Anal Fissures
Various chronic diseases can increase the risk of anal fissures. Diseases such as chronic inflammatory bowel diseases like Crohn’s disease and ulcerative colitis can be accompanied by inflammation in the anal area, which can consequently also lead to anal fissures.
Similarly, Behçet’s disease, a chronic inflammatory autoimmune disease that can affect many organs and tissues including the skin, eyes, joints, and also the digestive tract or anal area. One of the common manifestations of the disease is lesions or ulcers that can occur in various parts of the body, including the oral mucosa, genitals, and anal area.
Infectious Diseases as Causes and Risk Factors for Anal Fissures
Certain infectious diseases such as syphilis, tuberculosis, or leishmaniasis can damage the mucosa in the anal area and thereby promote the occurrence of anal fissures. Viral diseases like HIV/AIDS, herpes simplex virus (HSV), or cytomegalovirus can also weaken the immune system and increase susceptibility to anal fissures.
Medications as Causes and Risk Factors for Anal Fissures
Some medications such as ergotamine, nicorandil, isotretinoin, or certain chemotherapeutics can damage the mucosa in the anal area and thus increase the risk of developing an anal fissure.
Anal Intercourse or Mechanical Overstrain as Causes of Anal Fissures
Mechanical strain from anal intercourse can cause injuries and tears in the anal region, increasing the risk of anal fissures. Anal sexual practices can also lead to tears in the anus. In some cases, various anal sexual practices, for example involving sex toys that cause injuries to the mucosa or even an anal tear, are the cause of an anal fissure.
Cryptitis and Anal Fistulas as Causes of Anal Fissures
If the anal mucosa (anoderm) is already damaged, as can be the case with cryptitis or enlarged hemorrhoids, there is a possibility that even normal bowel movements can cause a chronic wound in the anal canal. Cryptitis refers to inflammation of the anal glands. These glands open into the small crypts at the transition between intestinal mucosa and anal skin. Inflammation of the glands can lead to the formation of a superficial fistula tract under the anal skin, which can then break open in the area of an anal fissure. Read more here about cryptitis or about anal fistulas.
High Sphincter Pressure as a Cause of Anal Fissures
High sphincter pressure leads to reduced blood flow, which can hinder or impair the healing of an anal fissure. Muscle tension is a consequence of the painful condition in anal fissures. This tension contributes to the wound edges being pressed together after bowel movements. Measures to relax the muscles can therefore help the wound to clean better and heal from the inside out.
Colorectal Surgeries as a Cause of Anal Fissures
Finally, surgeries in the rectal area can affect the surrounding tissue and promote the occurrence of anal fissures. Wound healing disorders after colorectal surgeries for other reasons, such as with hemorrhoids, anal abscesses, anal fistulas, or anal vein thromboses can also lead to chronic wounds in the anal area. These wounds in the anoderm can resemble an anal fissure. Therefore, surgical procedures on the anus are generally only performed if there is no effective therapeutic alternative in the treatment of an anal fissure and the patient's suffering is very severe. Read more here about the anal fissure operation.
Stress as a Cause and Risk Factor for Anal Fissures
Stress plays a significant role in the development of anal fissures. Psychosocial stress often leads to tension in the pelvic floor muscles and the sphincter, which inhibits blood flow. This can not only increase the risk of tears but also delay healing. Relaxation techniques such as breathing exercises or yoga can play a supportive role here. Psychosocial stress also affects digestion and can promote diarrhea or constipation.
Find comprehensive information here about the various measures for preventing anal fissures or about diagnosis and examinations of anal fissures by a doctor in the blog post Anal Fissure Doctor. Here you can learn more about the symptoms of anal fissures or the general treatment of anal tears.
