Anal fistula is an abnormal channel formed by the anal canal or rectum with the adjacent tissues and organs around the anus for pathological reasons. It is a common disease, usually formed by perianal abscesses formed by infection of the anal glands, and after the abscesses break down or are incised, the walls of the growing canal form a fistula; there are also a few cases formed by the collapse of perirectal abscesses complicated by other diseases, such as ulcerative colitis.
Etiology
The cause of anal fistula according to the ancestral medicine is not only internal injury, but also external infection, unclean diet, and long term disease, resulting in disharmony of yin and yang in the body, and poor flow of Qi and blood, so that the evil can take advantage of the deficiency and stay in the large intestine. The objective law that internal causes are the basis for change and external causes are the conditions for change is consistent with clinical reality.
The cause of anal fistula is mainly bacterial infection, the site of bacterial invasion is the anal fossa, anal gland ducts and anal glands, the anal gland infection and pus can flow around the anorectum or linger under the intestinal mucosa, when the abscess is self-collapsed or cut open to drain the pus, anal fistula caused by anal gland infection accounts for 95-97%, only a few cases due to ulcerative colitis, Crohn’s disease, multiple There are only a few cases due to ulcerative colitis, Crohn’s disease, multiple purulent sweat glands, and a few cases due to rectal injury and inappropriate withering of hemorrhoids.
Anal gland
(a) Anatomy of the anal gland
(B) What is the anal gland
Anal gland: also called anal duct, intramuscular gland, deep rectal gland. They vary greatly in form, number, structural pattern and distribution. In adults, there are 4-10 anal glands, usually no more than 8, and in newborns, up to 50, located in the submucosa or internal sphincter of the lower pectineal region of the anal fossa, sometimes reaching the joint longitudinal muscles.
The opening of the anal glands: sometimes, one anal gland opens in one anal saphenous fossa, or two anal glands open in the same saphenous fossa. Not all fossae are connected to the anal glands, and about half of the fossae do not have an opening for the anal glands. A very small number of anal glands may open directly into the anal canal and rectum.
(iii) Location and course of anal glands
1.Most anal glands are concentrated in the posterior part of the anal canal.
2.Adult anal glands are mainly concentrated in the posterior part of the anal canal, with fewer glands on both sides and almost no glands in the anterior part.
3.The anal glands are scattered around the anal canal.
4.The anal gland opening and the anal gland duct are on the same vertical line (the line between the dentary line and the anal gland duct) in 65% of cases, and not on a vertical line in 35% of cases.
(D) Controversy about the anal gland – the nature of the anal gland
One opinion is that anal glands are degenerated tissues with no secretory function and are remnants of the embryonic development process, which have no functional significance.
Another opinion is that the anal gland exists in all periods of human embryonic development and is an independent structure that maintains its secretory function as a gland for life.
(E) Clinical significance of the anal glands
1, the anal gland is the total source of all perianal disorders
2. 95% of all anal fistulas originate from anal gland infection
3. The importance of the anal glands in physiology, pathological anatomy and perianal infections is indisputable.
(6) Functions of the anal glands
1.Assist in defecation
2.Protect the anal canal
Anal fistula pathology
The formation and development of l abscess can be divided into the following stages.
l early bacterial invasion stage
lpus formation stage
lStage of fistula formation
lAs a whole, an anal fistula is generally composed of four major parts: the internal port, the main port, the branch port, and the external port.
Classification of anal fistula
The classification criteria of anal fistula established by the Chinese Society of Traditional Chinese Medicine, Anal Branch in 2002.
Low anal fistula
(1) low simple anal fistula
2）Low complex fistula
High anal fistula
1）high simple fistula
2）high complex fistula
Clinical symptoms
pus flow
pain
anal itching
hard strip-like swelling at the anal verge
Systemic symptoms
Examination I to determine the location of the internal orifice
lDetermine the location of the internal opening from the medical history
palpation can help to understand the location of the internal orifice
lDetermine the location of the internal orifice by the distance between the external orifice and the anal opening
lSolomon’s law can help to diagnose the internal orifice
lProbe examination
lAnoscopy
lStain examination
lIodine oil imaging, endorectal ultrasound and intraoperative exploration
lMRI (magnetic resonance imaging) and spiral CT 3D reconstruction
Determining the relationship between the depth of the fistula and the sphincter
As the tube of anal fistula passes through the external sphincter or anal raphe, sometimes the tube travels between the internal sphincter, and cutting the tube during surgery will inevitably cut the relevant anal sphincter, especially the fistula that passes through the anorectal ring, and cutting the anorectal ring will cause anal incontinence after surgery, so the relationship between the travel of the fistula and the anal sphincter must be clarified during the examination.
The diagnosis of anal fistula must understand its main lesion
The fistula is not a localized fistula, but must be analyzed comprehensively in order to
The first step is to understand the appearance of the anus.
First of all, the scope of the lesion should be understood from the appearance of the anus
Second, the depth of the lesion, the direction of the canal, and the direction of the anal sphincter should be understood from the frontal surface.
direction and the relationship with the anal sphincter, and the location and number of internal openings
Second, the relationship between the lesion and the anterior and posterior rectum should be understood from the sagittal plane.
Whole body examination
Although the lesion is localized, the whole body examination must not be neglected, especially for those with unclear internal orifices, and attention must be paid to the presence of presacral lesions. In particular, we should be careful with complex fistulas, and if necessary, we can do bacterial culture and antibiotic sensitivity test, pay attention to blood sedimentation, blood picture and anal sphincter function measurement, and in some suspicious cases, we can also do biopsy to determine the nature of the fistula, and we should especially observe whether there is cancer.
Differential diagnosis
l perianal septic disease
sacrococcygeal fistula
sacrococcygeal teratoma
lSacroiliac tuberculosis
Diagnostic hints
1 The presence of an anal fistula can be considered when there is a history of a perianal abscess that breaks down on its own or after performing an abscess incision and the wound does not heal with repeated swelling and pain and pus flow. The external opening is often around the anus or any part of the buttocks, forming a depression or a protrusion on the skin surface, with pus overflowing when pressed, and the surrounding skin is often peeling due to the stimulation of pus and secretions, sometimes with granulation tissue protruding from the internal opening.
2 tuberculous anal fistula, the external mouth is large, the shape is not neat, the edge is sunken, the surrounding skin is yellowish, the secretion is thin and abundant, and the wall of the tube is not hard.
3 Low-grade anal fistulae can be palpated under the skin with hard strips, from the external orifice to the anus, and pus overflows from the external orifice when lightly pressed with the finger.
Diagnostic tips
l In high anal fistula, there are hard scars near the rectal ring of the anal canal, mostly on the posterior and sides, and there are also large scars in the colorectal fossa, sometimes hard strips are felt in the rectal wall, and the internal orifice is often near the dentate line or the lower part of the rectum, and small hard nodules can be felt by finger palpation, and the central depression of the hard nodules is the internal orifice, and this depression is mostly on the posterior median line of the anal canal or slightly to one side.
The fistula is in the rectal wall and can be palpated by finger palpation.
Treatment
Treatment of anal fistula is divided into non-surgical and surgical therapies.
The purpose of non-surgical treatment is to control the infection, reduce symptoms and control the development, but it cannot be completely cured, or is relatively cured for a while and can easily recur.
Drug treatment
topical medication
Topical ointment
lChinese medicine treatment
The purpose of surgical treatment is to completely remove the infected anal glands and remove the infected foreign body from the fistula, which is the key to treatment. However, for anal fistulas that infringe on the function of the anal sphincter, especially for lesions involving the anorectal ring, they must be treated correctly to avoid the sequelae of anal incontinence.
1.incision method
2.Cutting and suturing method
3.Cut and hang method
Treatment tips
1.Open wound to facilitate drainage
2.All anal fistula incisions are in radial shape
3.Protect the physiological function of the anus
4. When cutting the canal, the sphincter on the surface of the fistula must be cut, but if the fistula passes through the rectal ring of the anal canal, it should be treated correctly to prevent anal incontinence, and the external sphincter in front of the anus should not be cut at once because it lacks the support of the puborectalis muscle. If the fistula travels above the deep external sphincter and cannot be preserved, it is slowly cut off using Chinese medicine hanging thread therapy.
If the fistula is deeper than the anorectal ring and the anorectal ring is not fibrotic, the fistula should never be cut all at once so as not to damage the anorectal ring and should be cut in the anorectal ring with a wire. If the anorectal ring is fibrotic, it can be directly cut vertically and will not cause complete anal incontinence.
If the caudal ligament needs to be cut, it can only be cut longitudinally, not transversely. If the caudal ligament needs to be cut transversely, the severed end of the ligament must be re-sutured and fixed to avoid causing anal collapse and forward displacement.
Problems to be noted in the treatment of high anal fistula
1. about the treatment of the internal opening
2. pay attention to the principle of changing the medicine to create muscle
3.Pay attention to the smooth drainage to prevent granuloma edema