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

48sec

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What should I do about an anal fistula?

Anal fistula is a disease that occurs when repeated infections in the anal crypts extend to the surface of the skin around the anus. Once formed, there are typical fistula tracts with both internal and external openings. Simple anti-inflammatory drug treatments can only relieve the symptoms of inflammation during the acute phase of an anal fistula. For the fistula tracts themselves, these treatments do not completely cure the condition. It is recommended that patients with an anal fistula undergo a fistulotomy as soon as they are diagnosed. Through surgery, the fistula tract and its walls can be completely excised, completely removing the local lesion, thereby further accelerating the regrowth of fresh granulation tissue locally.

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Written by Yu Xu Chao

Colorectal Surgery

1min 6sec

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Is it better for the external opening of an anal fistula to be closed or not closed?

In clinical practice, it is generally best not to close the external opening of an anal fistula. Keeping the drainage unobstructed can prevent the infection from worsening or the formation of multiple branches. This is because when the fistula drains properly, the infectious secretions can flow out of the external opening. However, if the external opening does close, the infected tissues and secretions will accumulate within the fistula and then spread to the surrounding areas, forming branches and leading to an increase in the number of branches, thus creating a complex anal fistula and increasing the difficulty of future surgeries. Therefore, it is best not to close the external opening of an anal fistula. Clinically, the treatment for an anal fistula involves fistulectomy, which primarily involves removing the internal opening and the fistula. The external opening also needs to be treated. Postoperatively, medications such as erythromycin ointment gauze strips should be used for dressing changes.

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Written by Yang Dong

Colorectal Surgery Department

33sec

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Anal fistula etiology

The cause of an anal fistula is due to infection of the anal glands. In normal human anatomy, there is a location at the junction of the rectum and the anal canal called the anal sinus or anal gland, which is relatively weak. If it is damaged, intestinal bacteria can enter the anal gland, causing inflammation. Over time, the infected anal gland leads to further abscesses towards the perianal space, causing a perianal abscess. After the perianal abscess ruptures, it further develops into an anal fistula.

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Written by Chen Tian Jing

Colorectal Surgery

1min 1sec

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Symptoms of cancerous transformation in anal fistula

The vast majority of anal fistulas do not undergo malignant transformation. However, there is a possibility of cancerous changes if an anal fistula that has repeatedly recurred over a long period is not treated aggressively, or if the inflammation of the fistula tract is severe. When an anal fistula undergoes malignant transformation, the secretion from the local fistula tract increases and is accompanied by a foul smell, and there may even be ulceration of the local fistula tract mucosa. Further surgical procedures, such as fistulotomy with seton placement, are required, and the excised fistula tract suspected of high-grade malignant transformation should be sent for pathological examination. If malignant transformation is confirmed, further pelvic MRI examinations are necessary to determine whether there is local and surrounding lymph node metastasis.

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Written by Deng Heng

Colorectal Surgery

44sec

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Does an anal fistula require surgery?

The treatment of anal fistula mainly focuses on surgical treatment, with medication as a secondary support. This means that without surgery, an anal fistula essentially cannot heal. Non-conservative treatments for anal fistulas are only temporary symptomatic treatments that manage the condition and alleviate clinical symptoms. For example, during an acute attack of an anal fistula, anti-inflammatory drugs can be used to temporarily relieve symptoms such as pain. Therefore, surgery is necessary for anal fistulas, as surgical treatment can completely eradicate the source of the disease, addressing the internal and external origins of the fistula for a complete cure.