Anal fistula ：
An anal fistula is a small channel that can develop between the end of the bowel and the skin near the anus. An anal fistula can cause bleeding and discharge when passing stools and can be painful. It can also occur after surgery to drain an anal abscess.
Usually constant pain, throbbing that is worse when sitting down
Skin irritation around the anus, including swelling, redness and tenderness
Discharge of pus or blood
Constipation or pain associated with bowel movements
Usually clinical evaluation, including a digital rectal examination is sufficient to diagnose an anal fistula. In rare cases, an examination may be done under anesthesia. Further testing with ultrasound, CT scan and or an MRI, might also be needed.
Surgery is the only option when it comes to treating anal fistula. There are several stages to treating an anal fistula. Definitive treatment of a fistula aims to stop it from recurring. Treatment depends on where the fistula lies, and which parts of the anal sphincter it crosses.
There are several options
Fistulotomy: This is used in 85-95% of cases and involves cutting open the whole length of the fistula in order to drain the contents. Once the fistula has been laid open it will be packed on a daily basis for a short period of time to ensure that the wound heals from the inside out.
Seton techniques: If the fistula is in a high position and it passes through a significant portion of the sphincter muscle, a cutting seton may be used. Seton is a piece of thread or other material, which is left in the fistula tract. The seton is tightened over time, gradually cutting through the sphincter muscle and healing as it goes. Sometimes several operations are necessary.
Advancement flap procedures: This option is usually when the fistula is considered complex, or is there is a high risk of incontinence. The advancement flap is a piece of tissue that is removed from the rectum or from the skin around the anus. During surgery the fistula tract is removed and the flap is reattached where the opening of the fistula was.