An anal fistula is also called a fistula-in-ano. It is an abnormal passage between the anal canal and the skin. It can lead to pain and inflammation, as well as systemic symptoms in some patients. Many different symptoms may be associated with an anal fistula, depending on the cause of the condition and other factors.
It is common for patients with anal fistula to report irritation or itching of the skin surrounding the anus. The medical term for this is pruritus ani, which means itchy skin around the anus.
In many cases, there may also be some swelling in the area, which is the result of skin irritation and inflammation.
Pain and Inflammation
Many patients report a constant, throbbing pain in the affected area around the anus throughout the day that does not cease.
The pain often worsens in intensity during certain activities, such as sitting, moving around, bowel movements or coughing. Patients may describe the intensifying of the pain to a burning, cutting or tearing type at such times.
Bleeding or Discharge from the fistula
Patients often report a discharge of foul-smelling or bloody material from outside the anal opening associated with pain. In some patients, the pain may reduce when the discharge begins.
Bleeding or Discharge per anus
Some patients with anal fistula may have a discharge of pus or blood in their stools, referred to as bloody or purulent stools.
A small amount of bright red blood on the surface of the stool is the most common type of anal bleeding, but some patients may not experience any obvious bleeding or discharge. The blood is not usually present inside the stool but on the surface of the stool.
There are also some symptoms often associated with anal fistula that are caused by a particular condition which causes or contributes to the fistula, such as an abscess or another health condition like Crohn’s disease.
Symptoms due to anorectal abscesses
The majority of anal fistulas are caused by an anorectal abscess. They often become infected, leading to the presence of systemic symptoms. These may include:
- Feeling unwell
- Swelling around the anal orifice
Symptoms due to intestinal inflammation
Additionally, some cases of anal fistula may be caused by intestinal inflammation, such as in Crohn’s disease. This is associated with other symptoms such as:
- Abdominal pain
- Loss of appetite
- Weight loss
Symptoms for Diagnosis
The presenting symptoms are a significant factor in the diagnosis of anal fistula and it is important that the characteristics of the condition are discussed during the diagnostic process.
In particular, the nature of the skin irritation, pain, and discharge, as well as the presence of blood in the stools, should be covered in the patient consultation, in addition to other symptoms that may be associated with particular causes of the condition.
Reviewed by Dr Liji Thomas, MD.