causes of anal fistula

Written by Yang Dong
Colorectal Surgery Department
Updated on September 27, 2024
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Anal fistula is one of the common diseases in proctology. The formation of an anal fistula is caused by infection of the anal sinuses and anal glands. Due to damage to the anal sinuses and anal glands, bacteria from the intestines enter these areas. As immunity weakens, the bacteria cause localized inflammation, which then leads to the formation of an abscess. After the abscess bursts, an anal fistula forms. This is the pathogenesis of anal fistula.

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Written by Chen Tian Jing
Colorectal Surgery
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How to deal with the internal opening of an anal fistula?

The internal opening of an anal fistula is generally located at the site of inflammation in the anal crypt. The primary reason for the formation of an anal fistula is the repeated outbreaks at the anal crypt, which lead to further infection and the formation of a perianal abscess. When the abscess cavity ruptures, it forms an external opening and the anal fistula. Surgical treatment is required for the internal opening of an anal fistula, generally involving a seton procedure that threads a line through the internal opening and part of the sphincter muscle, gradually cutting and draining the area slowly. If the inflammation at the internal opening is significant, it may also be necessary to excise part of the infected site in the anal crypt. Post-surgery care of the internal opening of an anal fistula primarily involves dressing changes, requiring daily thorough disinfection of the local area, ensuring clear drainage, to allow the granulation tissue at the internal opening to grow freshly, and to slowly heal the wound without infection. (Medication should be taken under the guidance of a doctor.)

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Written by Chen Tian Jing
Colorectal Surgery
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The difference between perianal abscess and anal fistula

Perianal abscesses and anal fistulas both belong to local infectious diseases of the anus. A perianal abscess represents the acute phase of infection, characterized by significant localized subcutaneous swelling, heat, pain, and the formation of pus and abscesses. Once the pus breaks through the skin and discharges, it naturally forms an anal fistula. Anal fistulas represent the later stages or dormant phases of local infections. Both perianal abscesses and anal fistulas require surgical treatment. The surgical method for perianal abscesses mainly involves a one-time radical surgery for the abscess, while the surgical approach for anal fistulas primarily involves fistulotomy with seton placement, followed by regular wound cleaning and dressing changes post-surgery.

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Written by Yu Xu Chao
Colorectal Surgery
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Are hemorrhoids the same as anal fistulas?

Hemorrhoids and anal fistulas are two completely different diseases. Clinically, hemorrhoids can be divided into mixed hemorrhoids, internal hemorrhoids, and external hemorrhoids. Internal hemorrhoids are often characterized by intermittent, painless rectal bleeding, while external hemorrhoids primarily cause symptoms such as a foreign body sensation in the anus and itching. For the treatment of hemorrhoids, if the condition severely affects the patient's normal life, surgical treatment can be considered, such as external peeling and internal ligation surgery, and internal hemorrhoid banding. Anal fistulas are mainly due to perianal abscesses that rupture spontaneously or are incised and drained, subsequently forming an anal fistula, which causes the patient to experience recurrent perianal swelling pain and pus and bloody discharge. Treatment for anal fistulas can only be surgical, and early surgical intervention tends to result in relatively fast postoperative recovery. The surgery mainly involves the removal of the internal opening and the fistula tract, followed by diligent postoperative dressing changes to promote wound healing.

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Written by Chen Tian Jing
Colorectal Surgery
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Does an anal fistula hurt?

Anal fistula mainly refers to the presence of a noticeable fistula in the tissue under the perianal skin, which connects the inner opening in the anal canal and the outer opening around the anus. Usually, the anal fistula does not cause significant pain when it is not in acute flare-up. However, if the anal fistula enters an acute episode, there may be pain due to inflammation at the local external opening of the anus, and possibly an increase in purulent discharge, which can irritate the skin around the external opening, causing stinging pain and itching. To prevent recurrent episodes of anal fistula and further aggravation of the condition, it is advised to seek surgery as soon as the fistula is detected.

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Written by Yang Dong
Colorectal Surgery Department
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What department should I see for anal fistula?

Anal fistula is caused by infection of the anal sinuses and glands. It manifests as hard lumps or cord-like objects around the anus, and may involve recurrent swelling, pain, and discharge of pus. In such cases, it is necessary to consult a colorectal surgeon. Generally, if diagnosed with an anal fistula, surgical treatment is required, as conservative treatment usually does not result in a cure.