An anal fistula is a fistula formed by the gradual reduction of the pus cavity after a perirectal abscess breaks down or is incised to drain the pus. It is also known as anal fistula and hemorrhoidal fistula. It is generally composed of a primary internal opening, a fistula and a secondary external opening. The fistula is mainly characterized by localized pus, lumps, pain and itching, but in the acute inflammatory phase and chronic complex fistula, it can be accompanied by systemic symptoms such as fever, anemia, wasting and loss of appetite.
Etiology and pathogenesis
Anal leakage is caused by the accumulation of dampness, heat, stagnation and toxicity, and poor blood flow.
Clinical manifestations
1. Symptoms Repeated episodes of perianal swelling and pain, pus flow, and fever during acute inflammation.
2. Local examination Visual examination shows the shape, location and secretion of the external opening. A superficial anal fistula can be palpated around the anus with a hard cord-like node and its path. Internal orifice, depression and nodules can be palpated by rectal palpation; anal sphincter function can be assessed in general.
Auxiliary examination
1.Probe examination Preliminary exploration of the fistula.
2.Anorectal microscopy Used in conjunction with hydrogen peroxide or methylene chloride, it can initially determine the location of the internal orifice.
3.Fistulography A contrast agent such as pantopamine can be used, especially for the diagnosis of complex anal fistulas.
4.Endorectal ultrasound To observe the course of the fistula, the internal opening, and to determine the relationship between the fistula and the sphincter.
5.CT or MRI is used for the diagnosis of complex anal fistula, which can better show the relationship between the fistula and the sphincter.
Classification of anal fistula
1.Domestic classification
(1) Low anal fistula
Low simple anal fistula: the internal opening is in the anal saphenous fossa, and only one fistula passes through the subcutaneous or superficial part of the external sphincter and communicates with the skin.
Low complex anal fistula: there are more than two internal or external ports, and the fistula passage is subcutaneous or superficial in the external sphincter.
(2) High anal fistula
High simple anal fistula: the internal orifice is in the anal saphenous fossa, and there is only one fistula tract, which travels above the deep layer of the external sphincter.
High complex anal fistula: there are more than two external openings, connected to the internal opening through the fistula or with a branched cavity, and its main tube passes above the deep layer of the external sphincter.
2.Paks classification
The classification of anal fistula depends on the relationship between the fistula and the anal sphincter, and is divided into intersphincter type, trans-sphincter type, over-sphincter type, and external sphincter type. A fistula is considered complex when it crosses more than 30% to 50% of the external sphincter (high intersphincter, supra-sphincter, external sphincter), female anterolateral fistula, multiple fistulas, recurrent fistulas, or fistulas with anal incontinence, which may cause anal incontinence after treatment.
Differential diagnosis
Anal fistulas need to be differentiated from anterior sacral sinus tracts, ruptured sacral abscesses, ruptured sacrococcygeal osteomyelitis, sacrococcygeal teratomas and sacrococcygeal cysts with outward ulceration secondary to infection, perineal urethral fistulas, sacrococcygeal bone tuberculosis, and purulent sweat glands. Anal fistula and perianal abscess are two stages in the development of a disease, a chronic stage of inflammation. Therefore, the differential diagnosis of anal fistula can refer to perianal abscess.
Treatment
1. Internal treatment
(1) Damp-heat infusion type
Symptoms: perianal pus flow, thick pus, anal swelling and pain, local redness and burning, thirst for drinking, unpleasant stool, short red urine, and heavy body. The tongue is red with yellowish greasy coating and the pulse is stringent.
Treatment: Clearing heat and detoxifying toxins, removing dampness and subduing swelling.
Formula: Dioscorea Z and Five Flavors Disinfectant Drink plus reduction
Dioscorea Z15 g Coix Seed 30 g Poria 15 g Slippery Rock 30 g Dampness 15 g Zelia 15 g Tongcao 6 g Huangbai 12 g Jin Yinhua 15 g Wild Chrysanthemum 15 g Dandelion 15 g Zihua Di Ding 15 g
Commonly used Chinese patent medicine: Yiqing capsule
(2) Fire and Poison
Symptoms: Sudden swelling and pain around the anus, continuously increasing; accompanied by vicious cold, fever, constipation, short red urine, redness and swelling around the anus, obvious tenderness, hard texture, burning surface. The tongue is red, with thin yellow coating, and the pulse is counted.
Treatment: Clearing fire and detoxifying toxins, removing blood stasis and dispersing nodules.
Formula: Wu Wei Disinfectant Drink combined with Xian Fang Livestrong Drink plus reduction
Honeysuckle 10 g wild chrysanthemum 10 g dandelion 10 g dahurica 10 g frankincense 10 g myrrh 10 g soapberry 10 g piercing sorrel 10 g g gweiwei 10 g red peony 6 g
Commonly used traditional Chinese medicine: Rhizoma Rhizoma
(3) Evidence of deficiency of the right and evil
Symptoms: intermittent perianal pus flow, thin pus, dull skin color of the external orifice, fistula festering and healing, vague pain in the anus; may be accompanied by fatigue and weakness. The tongue is light with thin coating and the pulse is moist.
Treatment: Tonify the Qi and Blood, tonify the Qi and Blood, and disinfect the toxin.
Remedies: Tori Disinfection San Plus Reduction
Ginseng 15 g Chuanxiong 10 g Angelica sinensis 10 g Paeonia lactiflora 15 g Atractylodes 15 g Yinhua 10 g Poria 15 g Angelica dahurica 10 g Saponaria 15 g Licorice 6 g Radix et Rhizoma 6 g Astragalus 10 g
Commonly used traditional Chinese medicine: ten whole tonic pills
(4) Evidence of deficiency of yin fluid
Symptoms: perianal ulceration, depression of the external orifice, subterranean fistula, often localized without hard cords can be found, thin pus; may be accompanied by hot flashes and night sweats, irritable heart and dry mouth. The tongue is red, with little coating and a fine pulse.
Treatment: Nourishing Yin and clearing heat
Formula: Artemisia annua and turtle nail soup with reduction
Artemisia annua 6 g turtle nail 15 g fine raw earth 12 g Zhi Mu 6 g Dan Pi 9 g
Commonly used traditional Chinese medicine: Zuo Gui Wan
2.External treatment method
(1) fumigation method: is a simple and easy to use important method after anal fistula surgery. The first thing you need to do is to boil the drug with water and smoke it before washing it, or use a towel dipped in the liquid to make a wet hot compress, which has the effect of activating blood and relieving pain, astringent and swelling, etc. It is commonly used in Wu Bei Zi Tang, bitter ginseng soup, hemorrhoid lotion, etc. After the wound is healed, 10% salt water with a small amount of pepper water can be used to sit in the bath.
(2) dressing method: the drugs used all depend on the surgery, using Jiu Yi Dan, red oil cream, Qing Dai San, Sheng Ji San and other lines of medicine embedded in the various stages of the wound, to play the role of lifting pus to decay, clearing heat and detoxification, muscle growth and closure, to help the wound healing.
3.Surgery
Surgery is the main treatment method for anal fistula. Different surgical methods should be used depending on the type and severity of the fistula.
Surgical principles
(1) Correct treatment of the infected internal orifice is the key to successful surgery.
(2) The main tube located below the rectal ring of the anal canal or passing 1/3 of the way below the rectal ring is treated by the incision method.
(3) The main tube located above the anorectal ring or through the upper 2/3 of the rectal ring, using the hanging method.
(4) proper treatment of the wound to allow unobstructed drainage and prevent pseudo-healing
(5) If the deep fistula passes above the anorectal ring and the anorectal ring is not fibrotic, it is absolutely not possible to cut the fistula all at once, and it is also forbidden to cut the sphincter in two places below the anorectal ring all at once to avoid causing anal incontinence.
(1) Hanging wire therapy: At present, rubber bands are used instead of silk wires, which can shorten the course of treatment and reduce postoperative pain. Reasonable choice of cutting hanging wire and drainage hanging wire.
First-stage cutting and hanging wire: applicable to high anal fistula involving most of the anal sphincter above the superficial part.
Second-stage cut and hang line: suitable for some high anal fistulas combined with difficult residual cavity, or requiring secondary surgery and postoperative drainage.
Long-term drainage hook-ups: for patients with high trans-sphincteric Crohn’s disease fistulas to prevent recurrent abscess formation and to maintain anal function.
Short-term drainage: Although short-term drainage has been clinically reported to be effective in treating anal fistulae, with complete preservation of the sphincter muscle and without causing anal incontinence, it should be applied with caution due to its high recurrence rate.
(2) Incisional therapy: It is suitable for simple anal fistula and low-level complex anal leakage. The fistula incision is better, while the fistula excision is more invasive and takes longer time to heal; for high anal fistula incision, it must be combined with hanging therapy to avoid anal incontinence.
(3) Mucosal flap nudging: it is suitable for patients with high anal fistula with clear internal orifice and no serious infection and for female anterior anal fistula.
It can also be combined with incision, open placement, hanging and suturing to reduce trauma.
(4) Postoperative dressing change: daily dressing change should be done with careful observation of the wound to check for dead sinus cavities, the nature of secretions, the patency of drainage, the growth of granulation, etc. The drainage of narrow ducts should be blocked to the base to allow the granulation buds to grow from the base. When the wound surface has a lot of secretions with necrotic tissues, it is advisable to use antimicrobial gauze wet dressing and switch to Vaseline gauze strips to protect the wound surface when the granulation turns fresh. If the wound is deep, it should be flushed with hydrogen peroxide to prevent anaerobic bacterial infection. For wounds with adhesions, separate them in time; for wounds with a sudden increase in secretions, be alert to the presence of branched tubes and probe them if needed. The postoperative wound of a high complex anal fistula is usually very deep and large. The gauze stuffed in the cavity often dries out and sticks to the trauma during the first change, which often causes severe pain when it is removed. Postoperative patients should keep their bowels open, such as postoperative constipation, which often causes wound bleeding and aggravates pain. To prevent constipation, laxative capsules such as hemp seed soft capsule can be taken.
4.Other therapies
(1) Adhesive plugging method: For simple non-inflammatory anal fistula, fibrin glue plugging method is feasible, which has the advantage of no sphincter damage, does not affect anal function, and is easy to operate, but the recurrence rate is high.
(2) Treatment of special patients
Crohn’s disease anal fistula: try to treat conservatively along with systemic treatment. Asymptomatic Crohn’s fistulas do not require treatment; low Crohn’s fistulas are treated by fistulotomy; complex Crohn’s fistulas can be treated palliatively by hanging a line for a long time and closing the internal opening by pushing a mucosal flap if the rectal mucosa is largely normal.
The main drugs are: cypress, comfrey, horsetail, bitter ginseng, dahurica, angelica, and alum. Superficial fistulas are the main cause of fistulas, with the possibility of self-healing, and ineffective incision is an option.
Referral principles
1, the diagnosis is unknown, need to go further to higher hospitals for fistulography, rectal cavity ultrasound, CT or magnetic resonance imaging examination.
2. If the fistula treatment is mainly surgical and cannot be performed due to the conditions, the patient should be referred in time.
Most anal fistulas are the sequelae of anal canker sores, which should be treated with early surgery and commonly treated with anti-inflammatory and antibacterial drugs, such as broad-spectrum antibiotics, metronidazole and sulfonamides.