What is a fistula?
An anal fistula is a communication from the inside of the anal canal to the outside on the skin. It originates in an infection of a mucous secretion gland, which are located about 1.5-2 cm away from the margin of the anus inside the canal.
Existing types of fistula
The classification of the different types of fistula is related to the course they take. There are very simple fistulas which do not involve either of the two sphincters, fistulas crossing the internal sphincter and fistulas crossing both the internal and external sphincters. We call them subcutaneous, intersphincteric, transsphincteric or suprasphincteric fistulas. In addition, these paths can cross the musculature (the sphincters) more or less deeply and this makes the fistula more or less complicated to treat. Thus they are further differentiated into high or low fistulas.
Some fistulas may have more than one tract and some may occupy both sides of the anus, which are called horseshoe fistulas.
Logically, the most complex fistulas are those that have more than one tract or cross the sphincters at a deeper level.
Causes of fistulas
As we have already explained, the fistula originates in an infected anal gland which normally causes an abscess. This abscess will drain spontaneously or the surgeon will debride it, but only 50% of the time will it end up forming an anal fistula (if it is the first episode). If a patient has a second episode at the same site or the drainage hole does not close about a month after it has been drained, it is most likely an anal fistula.
Treatment of anal fistula
The most effective treatment is fistulotomy. This means opening the tract so that the tissue can grow in a natural way, forming a scar zone, without a tract. Sometimes this is not possible because it would endanger the patient’s continence. The fistula must then be treated in two stages. The first intervention would section part of the fistula and once marked with a fishing line (placement of a thread or rubber in the remaining tract), the entire fistula is sectioned in a second intention.
In complicated fistulas or fistulas that have been operated several times, advancing a mucosal flap to plug the internal orifice and drain the external orifice may be the best option.
Plugging the tract with different substances marketed for this purpose is another option, but not with the guarantees of healing that the previous ones have.
The surgeon should keep in mind that healing the patient, if possible in the first operation, is the most appropriate. About 25% of fistulas operated more than once become complex fistulas. For this the experience in treating this pathology is very important because there are several factors that influence indirectly in the healing such as the appreciation at the time of surgery of the amount of sphincter to be respected, the age (it is not the same in a young person than in an elderly person), obesity, the type of pelvic floor, the length of the anal canal that patient has, the shape of the resulting surgical wound thinking in the subsequent healing, etc. , but this is not protocolized, so the surgeon’s intuition will be what will command the good result.
Benefits and treatment of anal fistula
The benefit is healing. The risks are basically incontinence and recurrence of the problem. Incontinence is currently a situation that can be considered rare if the surgeon measures the risks, but the recurrence or persistence of the fistula is much greater due, on most occasions, to “incomplete” or “timid” surgeries due precisely to the phantom of incontinence. Many surgeons with great experience prefer to cure the process by surgery that theoretically threatens continence and reconstruct the sphincteric apparatus in the same operative act, under the premise that otherwise it will not be cured. This should be discussed at length with the patient. It should also be made clear that most fistulas are not complicated and curing them does not entail a risk of sphincteric dysfunction. In conclusion, knowing how far the surgeon can go is basic to obtain the best results and falling short of the above-mentioned problem: persistence of the fistula.