Journal of Colorectal Surgery 2000 Vol. 3 No. 6
1 What is "hemorrhoids"
People have known about hemorrhoids for 4000 years, but it has been difficult to give a correct answer to the definition of hemorrhoids.
Textual research on the name The Chinese character "hemorrhoids" is derived from the character "" in oracle bone inscriptions, which is the prototype of the ancient "anal" character. "Hemorrhoids" in ancient Chinese literature refers to anal diseases. "Hemorrhoids" and "fistulas" are often used together. For example, "Hemorrhoids and Fistulas" by Wang Boxue of the Song Dynasty and Huashou's "Hemorrhoids and Fistulas" are both anorectal diseases. focus on. "Hemorrhoids and fistula" in Chinese medicine is "anorectal". Therefore, "hemorrhoids" is not a specific disease name. There are two English "hemorrhoids": "Hemorrhoid" comes from the combination of the Greek words "haima" and "rhoor", which means bleeding or bleeding. Another name is "pile", derived from the Latin "pila", which means spherical or protruding, and does not refer to a specific name for a certain disease. The above concept has been in use today, and the public still tends to refer to all related anal symptoms as "hemorrhoids."
The legend of hemorrhoids Medieval Europeans respected St. Fiachra (ST. Fiachra) as "the patron saint of hemorrhoids." Patients with anal diseases often wear dried toads and talisman seals to pray for the blessing of this god. Around the time of Hippocrates, Western medicine began to explain "hemorrhoids" with the ancient theory of body fluids; they believed that hemorrhoids were formed by the accumulation of waste products from "spleen blood" and "bile". Galen in the second century AD also believed that hemorrhoids were a way for corrupting body fluids to be excreted from the body. Until 1729, Stahl insisted that hemorrhoid bleeding is a "self-purification" life phenomenon rather than a disease. It is when the body has too much blood. A kind of safety valve. So "hemorrhoids" are called "Golden Ader" in Old German, "flaxd'or" in Old French, and "profluvio disangue" in Old Italian, which means "bloody flood". This concept lasted for a long time in the West, so that some prominent figures were not properly treated. According to legend, in 1816, the French Emperor Napoleon suffered an attack of hemorrhoids during the Battle of Waterloo and the entire army was annihilated.
The discovery of anatomy gave the modern concept of hemorrhoids since the 18th century. Since the age of Morgagni (1761), hemorrhoids have been considered as varicose veins under the anal mucosa, and various explanations have been proposed, such as: human erect position, hemorrhoidal veins without valves, sphincter spasm or fecal impaction Hemorrhoidal venous reflux disorder caused by other diseases; or weakening of the hemorrhoidal vein wall due to injury or infection is considered to be the cause of hemorrhoids. However, this theory cannot give a satisfactory answer to many clinical phenomena. For example, some huge prolapsed internal hemorrhoids can sometimes expand the anus spontaneously or manually, which can obviously return to a completely normal state. Hemorrhoid bleeding is usually a large amount of bright red, so it is unlikely to come from the vein. If the prolapse of hemorrhoids is related to the relaxation of the anal canal muscle tissue, the anus of patients with hemorrhoids is often not loose, but in a tightened state. Patients with rectal prolapse do not have hemorrhoids. All these are not listed one by one. Therefore, the venous theory has been gradually abandoned in recent years. However, at the same time, some people have put forward more complex "new theories", such as anal canal stenosis theory, erectile histology theory, sinus vein theory, hemorrhoidal vein pump function decline theory, sphincter function decline theory, rectal anal canal force imbalance theory Theories, allergy theory, microelement factors, etc., are divergent. One reason is that it makes the concept of the term "hemorrhoids" more confusing; the nature of hemorrhoids is becoming more and more ambiguous.
Modern concept: In the 20th century, especially after the 1970s, with the advancement of science and technology, people's understanding of hemorrhoids has made a leap. At present, a new concept of hemorrhoids has been formed, namely:
—— Hemorrhoids are the lip-shaped fleshy fats or Anal Cushions at the lower end of the rectum, which is a normal structure that everyone has.
——The anal cushion is arranged in the right anterior, right posterior, and left three leaves, which has nothing to do with the branches of the superior rectal artery. They are like the tricuspid valves of the heart, helping the sphincter to maintain the normal closure of the anal canal.
-Pathological hypertrophy of the anal pad is called hemorrhoids.
——The principle of treatment of hemorrhoids is mainly based on symptoms. Even large hemorrhoids without symptoms are not necessarily an indication for treatment. On the contrary, hemorrhoids that are small but are at risk of serious complications must be treated.
The above concept was first proposed by Thomson in his master's thesis in 1975, and was supported by famous scholars such as Alexander-williams (1982), Bernstein (1983) and Melzier (9184). It was held in Cologne, Germany in 1983 The 9th International Hemorrhoids Symposium was unanimously confirmed. The new definition of hemorrhoids has been widely adopted in recent foreign monographs on anorectology. In order to deeply understand the nature of hemorrhoids, the anatomical, physiological and pathophysiological basis of the above concepts are analyzed as follows.
2 Seeing the essence of hemorrhoids from genetics
Anal cushion is also called haemorrhoidal zone or zona columaris. Embryologists call this zone a cloacogenic zone or transitional zone or invagination zone. al zone). Since this area is located at the junction of the anal canal and the intestine, the embryonic primordia of epithelium, glands, blood vessels and muscles are intertwined here, so it has its own morphological characteristics and is an important critical area.
Rectum descent and anorectal intussusception. In the early embryonic stage, the end of the original rectum (the hindgut) is located in the abdominal cavity, and it falls below the pelvic diaphragm to contact the original anal cavity at 3 months after birth; then the original anal cavity is inserted upwards into the lower end of the hindgut. At the intussusception, the posterior intestinal mucosa folds into a double layer, the inner side of which is the anal canal epithelium, and the three gradually fuse and thicken, forming a ring-shaped spongy tissue band, that is, anal cushion. Due to the contraction of the internal sphincter, the anal cushion is divided into three parts on the right front, right back and left side by the "Y"-shaped groove. This is usually the so-called "maternal hemorrhoids" and its "prone sites".
As early as 1954, Last discovered that the internal sphincter of the hindgut and the external sphincter of the original anus were arranged up and down during the viviparous period, and changed to the internal and external arrangement with the development of the human embryo; therefore, early scholars once referred to the former as the upper sphincter. , The latter is the lower sphincter. Stephens also pointed out in 1963 that the anal cushion epithelium (ie, hemorrhoid epithelium) at the end of the hindgut is not a colonic intestinal type, but a squamous epithelium from the original anus. The above findings can be used as evidence for anorectal intussusception.
Rupture of anal membrane and formation of ATZ epithelium Data show that the hemorrhoidal epithelium is ATZ epithelium. The occurrence of ATZ is related to the location of the anal membrane rupture. The anal membrane is the diaphragm between the original rectum and the original anus. The upper part of the anal membrane is the endoderm and the lower part is the ectoderm. In the past, from the embryology point of view, it has been believed that the anal membrane ruptures at eight weeks of pregnancy, and the ectoderm squamous epithelium crawls upward to form a transitional epithelial zone, the so-called ATZ. However, there are different opinions on the location of the anal membrane rupture. According to Nobles (1984) observation; the shape of the anal membrane provided to adults in the early embryo is only approximate, because with the appearance and migration of the sphincter, that is, the external sphincter grows upward, and the internal sphincter grows upward. Move down, the anal membrane attachment will change accordingly. The anal membrane ruptures before the anal flap (or tooth line) appears. The first appearance of the anal flap was about 30mm in the human embryo. At the 35mm stage of the human embryo, the upper boundary of the combi membrane reaches the junction with the rectal mucosa, and there is an overlapping area of squamous epithelium and columnar epithelium, which gradually expands to an adult about 15mm wide. Therefore, the anorectal junction does not have a clear dividing line, but an irregular area of squamous and columnar epithelium. The observation results of modern application of optics and electron microscope show that the ultrastructure of ATZ epithelium is similar to that of cloacal epithelium, thus confirming that the ATZ above the plane of the anal flap (or dentinal line) (anal cushion) represents the boundary between endoderm and ectoderm, that is, anal The attachment of the membrane is also the belt that connects the anal canal to the rectum. Fenger used alcian blue staining method to observe: the rectal columnar epithelium rich in mucin is stained dark blue, while the anal squamous epithelium does not stain if it does not contain mucin. The transitional epithelium of the anal cushion contains less mucin, so it is dyed light blue, which can be distinguished from the above two kinds of epithelium in turn.
In summary, from the genetic point of view, hemorrhoids are developed from anorectal intussusception, which is a normal structure of human anatomy.
3 Seeing the essence of hemorrhoids from the physiology of anal cushion epithelium
The mucosa of the anal cushion is purple-red, and the area bordering the rectum upward becomes pink. From the histological point of view, the anal cushion epithelium is a transitional epithelium between a single layer of columnar epithelium and stratified squamous epithelium, and the cells are columnar and cubic. Or low cubic shape, in which there are small islands composed of single-layer columnar or multi-layer squamous cells. Histochemical methods proved that there is a small amount of mucus on the surface of columnar cells or in the more typical goblet cells. Most of the squamous epithelium is undifferentiated. In about 31.9% of the population, the differentiated type is normal squamous epithelium, and its distribution area is at least 2mm.
In 1982, Fenger et al. found that there are endocrine argyrophilic cells or EC cells in the anal cushion epithelium. These cells seem to be connected with its mucosal nerve plexus. The pudendal nerve is cut off. The ribonucleic acid contained in argyrophilic cells is significantly reduced. Cells may initiate afferent excitement related to anal atresia.
In 1985, Taniguchi Rizou et al. used the enzyme antibody method (PAP method) to stain the anal cushion excision specimens for IgA tissue staining, and found that there were moderate to highly scattered and deeply stained secretory cells in the anal cushion epithelium. But in the rectal tissue above the anal cushion, it is rare to see such deeply stained cells. From this he inferred that if inflammation occurs in the anal canal area, the intraepithelial IgA secretion of the anal cushion will increase. Even after internal hemorrhoids are removed, IgA secretion is considered to be part of the prevention of infection.
The sensory nerve endings in the epithelium of the anal cushion are extremely abundant. Krause’s final ball, Glogi-Mazzoni body and Pacinian body are more numerous; the former is sensitive to temperature, and the latter is responsible for changes in tension. The number of Meissner corpuscles is relatively rare, with slight touch. In addition, there are somatic sensory nerves that extend across the dentinal line to the lower edge of the anal cushion. The distribution of nerves in the anal cushion is different from that of the skin, but has obvious similarities with the nerve branches of the lips. These nerves are important sensory devices in the anal reflex, and have a fine discrimination ability for the nature of the rectal contents. This discrimination may be the function of the rectal pressure. At rest, the anal cushion is closed, and the contents of the rectum will not contact the receptors. When hard, loose stools or gas inflate the rectum, the reflex causes a decrease in intraanal pressure (internal sphincter relaxation). At this time, different contents Contact with the sensory epithelium of the anal pad caused by different pressures can distinguish its nature and trigger a trial reflex. Therefore, although the area of the receptors in the anal cushion area is small, it can act as an alarm when the stool is close to the anus, so it has a certain protective function.
It is worth noting that the ATZ epithelium in the anal cushion area is a highly specialized sensory nerve terminal tissue zone, which is very sensitive and is the sensory center that induces defecation, also known as the trigger zone. When feces are sent from the rectum to the anal canal, the ATZ is stimulated to reach the brain through the sensory nerves to produce a sense of defecation. If this area is completely destroyed, the sensation of bowel movement disappears and the stool in the rectum will become stagnant. According to the physiological characteristics of the above-mentioned ATZ, it can explain the causes of some abnormal bowel movements in the clinic. For example, for prolapsed anal diseases (rectal prolapse, polyps, etc.), the prolapse is embedded outside the anus during defecation; after the stool is discharged, the prolapse remains in the original state, which stimulates the ATZ epithelium of the anal cushion and produces a defecation sensation. This kind of abnormal defecation sensation mistaken for normal defecation sensation is mistaken for residual feces and irritated, which promotes the generation of abnormal defecation sensation. As a result, the prolapsed body is more prolapsed, causing a vicious circle. This is why patients with rectal cancer in the lower rectum often have abnormal bowel movements.
In summary, the anal cushion epithelium has certain immune and endocrine functions, fine discrimination, and a variety of chemical and mechanical receptors, which can trigger a protective anal reflex, which is extremely important for maintaining normal defecation activities.
4 See the essence of hemorrhoids from the blood vessel
The branch pattern of suprahemorrhoidal artery has nothing to do with the location of mother hemorrhoids. In 1919, Miles proposed that the suprahemorrhoidal artery was divided into left and right branches, and the right branch was divided into anterior and posterior branches and distributed together with the left lateral branch in the hemorrhoid area, and emphasized that this branch pattern is related to the causes of the three female hemorrhoids. However, the research reports of modern scholars are not consistent with Miles's thesis. Michels (1965) divided the suprahemorrhoidal artery into 4 types, and no type described by Miles was found. Foster (1984) and Sen Keyan (1984) pointed out that the left and right branches of the suprahemorrhoidal artery can be divided into anterior and posterior branches or most of the secondary branches, without a fixed pattern. The author (1986) once dissected and observed 76 cadavers, and found that there were three types of right anterior, right posterior and left lateral as described by Miles. Only 5 cases were found, accounting for 6.6%. No statistical significance. Therefore, Miles used the branch pattern of the superior rectal artery to explain the prevalence of internal hemorrhoids, which lacked anatomical support. What's more, the blood vessels are mutated, and the positions of the right front, right back and left side of the anal cushion are fixed, and there is no logical connection between the two. It has been confirmed that the arteries of the anal cushion mainly come from the inferior rectal artery (middle hemorrhoidal artery) and anal artery (inferior hemorrhoidal artery); the superior rectal artery generally does not participate. The three-part arrangement of the anal cushion has nothing to do with the branching pattern of the superior rectal artery.
The traditional concept also believes that the density of microvessels in the hemorrhoid area is different. Because the blood vessels distributed in the right front, right back and left side are particularly dense, mother hemorrhoids often occur here. To this end, Haruo Miyazaki (1976) and the author (1986) observed the microvessel density in the anal cushion through arteriography, and found that the microvessels of the middle hemorrhoidal artery and the anal artery converge here from six directions. They are distributed equally throughout the week without bias. The microvessels on the right front, right back and left side were not found to be particularly dense compared to other places. If it is assumed that the cause of hemorrhoids is related to microvessels, hemorrhoids cannot be limited to only three specific places. Therefore, the distribution pattern of arterial capillaries in the anal cushion has nothing to do with the prone site of hemorrhoids.
Dilation of hemorrhoidal veins is not a pathological phenomenon. Today, people's understanding of hemorrhoids is still attributed to hemorrhoidal varicose veins. In fact, as early as the 18th century, SaPPey, Dyret, Waldeyer, and Thomson et al. all confirmed that from newborn babies to healthy adults, the venous expansion of the hemorrhoidal venous plexus is constantly present, which is different from the great saphenous vein or esophagus. Varicose veins are normal physiological expansion without any pathological damage to the vein wall. In 1982, French scholar Saint-Pierre discovered that female internal hemorrhoid plexus has estrogen receptors. When estrogen levels increase during pregnancy and menstrual cycles, stimulation of these chemical receptors can reflexively cause vein dilation, which is also a physiological phenomenon.
The submucosal venous plexus of the anal cushion (internal hemorrhoid plexus) is the same as the adjacent pudendal plexus, bladder plexus, and uterine-vaginal plexus. It is the normal pattern of pelvic organ veins. Under normal circumstances, there is extensive communication between the internal hemorrhoidal venous plexus and the portal vein and systemic veins in the rectum. Portal vein blood can be shunted to the systemic circulation (internal iliac vein) via the interhemorrhoid communicating vein and hemorrhoidal reproductive vein. The rectum contracts during defecation. The shunt phenomenon is more pronounced. In 1985, Shafik found through hemorrhoid plexography that the hemorrhoidal reproductive vein has the function of a venous valve, which only allows blood from the hemorrhoidal venous plexus to flow to the prostate venous plexus or vaginal venous plexus (systemic circulation), while the systemic blood cannot flow to the portal vein system. Therefore, there is no direct connection between portal hypertension and hemorrhoids. According to statistics, the incidence of hemorrhoids in patients with portal hypertension is not high. Jacous et al. (1980) investigated 188 patients with portal hypertension, 52 patients with hemorrhoids, accounting for 28%. However, the incidence of hemorrhoids in ordinary people is as high as 50-80%. Other scholars such as Hunt and Orloff have the same report. Therefore, the above conclusion has also been confirmed clinically. The hypothesis that portal hypertension is closely related to the pathogenesis of hemorrhoids, which was widely recorded in monographs in the anorectal department, has now been rejected. The traditional concept of hemorrhoids caused by blood stasis and varicose plexus has been abandoned. Since the internal hemorrhoid plexus is part of the rectal venous plexus, if the venous plexus is stasis, the latter has the effect of absorbing excessive congestion and will not cause varicose veins; if varicose veins occur, it will also involve the entire rectal venous plexus and will not be limited to internal hemorrhoids Clump. Therefore, the venous plexus of the anal pad is closely related to hemorrhoids. But it is not the main aspect of disease.
Arteriovenous anastomosis (anastomosis arteriovenosa) is the blood volume regulator of the anal cushion. In 1962, Stelzner et al. found that there was an arteriovenous anastomosis in the submucosa of the anal cushion in serial tissue sections. In 1963, Staubesand used X-ray angiography, and Thomson used latex injection in 1975, which successively confirmed the existence of this special blood vessel. Thomson calls such blood vessels "sinusoidal veins." The silk ball-like structure of the arteriovenous anastomosis is a unique blood vessel pattern in the anal cushion.
Arteriovenous anastomosis refers to a direct anastomosis tube between small arteries and small veins. Blood can flow from arteries to veins without passing through capillaries. Such blood vessels can go straight or be spherical or tortuous. The tube wall structure is very special: endothelial cells directly connect with deformed smooth muscle cells, and there are abundant nerve fibers in the outer membrane. Under normal circumstances, the opening or closing of the arteriovenous anastomosis in the anal cushion is alternately performed. It can be opened 8-12 times per minute. Some are open for several days or closed for several days. Because the anastomotic tube can be freely opened, it has a major effect on the temperature and blood volume of the anal cushion area. Because the arterial blood flows directly into the veins, the venous blood in the anal cushion venous plexus can be arterialized, and even rhythmic pulsation occurs in the veins. Thulesins, Gjores, etc. on the blood analysis of hemorrhoid blood and the experimental study of temperature conductivity (thermocnductibility). The existence of this kind of anastomosis tube in the anal cushion is strongly confirmed, and a reasonable answer is given to why the hemorrhoidal blood is bright red (arterial blood).
Arteriovenous anastomosis is a good blood volume regulator for the anal cushion. The amount of blood supplied to the anal cushion is closely related to its functional state and the stimulation of the internal and external environment. Under normal circumstances, the blood flow of the anal pad anastomosis tube accounts for 20% of the total rectal blood volume, even up to 50%. Due to low levels of sex hormones in children, the anastomotic tube is not fully developed until puberty, so children rarely experience anal hypertrophy. During pregnancy, the level of estrogen increases, the anastomotic tube becomes thicker, and the blood flow increases. Therefore, the incidence of hemorrhoids in pregnant women is high.
The contraction and relaxation of the smooth muscle of the arteriovenous anastomosis tube are innervated by sympathetic nerve fibers and regulated by vasoactive substances in the blood. There are two types of active substances, namely angiotensin (norepinephrine, epinephrine, serotonin, angiotensin, etc.) and vasodilator (histamine, vasomotor, vasodilator, nucleoside) Acid and lactic acid etc.). The former is systemic, and its concentration changes little. The latter is produced by local tissues. When the anal pad is stimulated by some unfavorable factors, it stimulates the sympathetic nerves. At first, the secretion of amines increases, causing anastomotic spasm. Tissue ischemia and hypoxia; then the anal pad tissue is stimulated by hypoxia to release histamine and produce local histamine effect, anastomotic tube dilation, blood stasis, tissue edema, blood clot formation, severe cases may develop into local necrosis, erosion Bleeding. Therefore, dysregulation of arteriovenous anastomosis may be one of the pathogenic factors of hemorrhoids.
5 See the essence of hemorrhoids from the anal cushion supporting tissue
There are two types of submucosal connective tissues in the anal cushion, namely supportive connective tissue and stable connective tissue; the former refers to the intrinsic components of the submucosa, and the latter refers to the fibers that join the longitudinal muscles through the internal sphincter and enter the anal cushion, and the inner surface of the internal sphincter , Forming a layer of fibromuscular tissue with collagen fibers, elastic fibers and smooth muscle fibers. Treitz first described this fiber in 1853, so it was called Treitz muscle. Fine-Lawes (1940) is called submucosal muscle.
In addition to the combined fibers from the combined longitudinal muscles passing through the internal sphincter, Treitz muscle also includes U-shaped retrograde fibers that partly surround the lower end of the internal sphincter. Some people also participate in the blurred fibers of the sphincter and the circular rectal muscle. Scholars have different opinions on whether to participate in the muscularis mucosa. The thickness of Treitz muscle is about 1 to 3mm, which increases with age and becomes stable after the age of 20. The ratio of Treilz muscle thickness to internal sphincter thickness: 1:4 for newborns. Adults are 1:1.5. The young Treitz muscle fibers are arranged finely. Parallel to each other, fine structure, more elastic fibers. By about 30 years of age, Treitz muscle fibers begin to degenerate, appear broken, twisted and loose, and elastic fibers decrease. The observation of Thomson (1975) confirmed the distribution of this fibrous tissue in the anal cushion. The hemorrhoid venous plexus is mainly wound in a network-like structure to form a supporting frame. Fix the anal cushion on the internal sphincter, its function is to prevent the anal cushion from slipping off. Therefore, Kohlvansch (1854) called Treitz muscle as a sustentator tuniae mucosae. The support device wrapped around the hemorrhoid blood vessels in young people is stronger and tougher, but in old age, degeneration occurs, the support device is loose, and the anal cushion tends to protrude from the anal cavity.
As mentioned above, the Treitz muscle is the network and support structure of the anal cushion. It has the function of retracting the anal cushion upward after defecation. If the Treitz muscle ruptures and the supporting tissues relax, the anal cushion can appear to be retracted and move down from its original fixed position on the internal sphincter. There are many factors that promote the lowering of the anal cushion. In addition to the genetic factors of congenital Treitz muscle dysplasia, such as constipation, irritation, chronic diarrhea, poor bowel habits and sphincter dysmotility, etc., they can increase the pushing down of the anal cushion. Vertical pressure causes Treitz muscles to overstretch and break, causing the anal cushion to move down. For another example, the arteriovenous anastomosis in the anal cushion is impaired, and the blood perfusion is greatly increased. At this time, if the internal sphincter tension is too high and the venous return is blocked, the anal cushion will appear congestive hypertrophy. The normal Treitz muscle collateral venous plexus has a restrictive effect on the volume of the anal cushion. When the congestion continues to increase, the volume of the anal cushion will continue to increase, resulting in the extension, hypertrophy and rupture of the Treitz muscle. Once the anal cushion loses the support of the muscular layer, over time, intermittent prolapse can occur, and then develop into continuous prolapse. It must be pointed out that the age factor cannot be ignored. It has been clarified in the 1960s that the fibers and cells of the anal cushion support tissue gradually degenerate with age. This is because the changes in glia-forming enzymes due to age affect the synthesis of glia and degrade natural glia. In 1984, Hass et al. pointed out that Treitz muscle degeneration began approximately at the age of 18-20, and it aggravated with age, becoming distorted and loosened, naturally broken, and anal cushions moved down, so the incidence of hemorrhoids increased greatly.
6 Seeing the essence of hemorrhoids from feces
Marti et al. (1989) pointed out that the normal anal cushion is like the tricuspid valve of the heart. Its main function is to assist the sphincter to ensure the normal closure of the anus and maintain fecal self-control.
The cushion-like structure is a common feature of various cavities lined by mucous membranes in the body, and it helps to close the cavities. For example, the rosette of the mucous membrane of the gastric cardia is similar to the anal cushion. It participates in the one-way valve of the cardia to prevent the reflux of gastric juice to the esophagus. Other pyloric valve, ileocecal valve, appendix valve, etc. all have functions similar to anal cushion. Alexander-Williams believes that the anal cushion is very similar to the lips; the lips have different shapes, such as thin, convex, wet, hyperemic, etc., and the anal cushion can also have different shapes and should not be called a disease. The three-lobed arrangement of the anal cushion is the most ideal valve device to adapt to the expansion or contraction of the anal cavity. Because there are abundant arteriovenous anastomosis and Treitz muscles in the anal cushion, the structure resembles the cavernous body of the penis, so Stelzner calls the anal cushion corpus cavernosum recti. The cavernous body can hold a large amount of blood, so that the blood supply of the anal cushion greatly exceeds its own metabolic needs, which can prove that the anal cushion has the characteristics of erectile tissue and is necessary for participating in anal self-control.
The size of the anal cushion is related to the opening or closing of the arteriovenous anastomosis tube and the amount of blood supply in the anal cushion. Work, defecation and changes in body position can all affect the increase or decrease of the anal cushion. If the anal cushion is transferred from the supine position to the upright position, the intravascular pressure of the anal cushion can rise rapidly from 22.5 to 24.5 kPa (230 to 250 mmH2O) to 58.8 to 73.5 kPa (600～750mmH2O). It can be said that the size of the anal cushion changes every day or every hour. After defecation, the anal cushion may come off or become congested, but after a period of rest, it can be seen that its volume is not large during rectal microscopy. The patient often complains: his "hemorrhoids" are sometimes large and sometimes not large; sometimes the "hemorrhoids attack" lasts for several days or weeks. Therefore, the traditional classification of internal hemorrhoids of stage I, II, III or IV is of little clinical and scientific significance. Since the normal anal cushion helps to coordinate the opening and closing of the anal canal, the anal cushion will be prolapsed or surgically removed too much, the anal self-control function will be damaged to varying degrees, and the percentage of patients with dirty stool, leaking stool or anal itching will increase.
7 Seeing the essence of hemorrhoids from pelvic floor dynamics
Shropshear has long discovered that the levator ani muscle fibers penetrate the wall of the anal canal through the combined longitudinal muscles to form the Treitz muscle; the anal cushion is fixed to the pelvic wall by this. Jit (1974) confirmed that these levator ani muscle fibers that penetrate the anal wall are not striated muscle but smooth muscle. Therefore, the relationship between changes in pelvic floor dynamics and hemorrhoids has attracted the attention of scholars in recent years.
Hancook-Smith (1975) found that the internal sphincter (IS) activity of some patients with hemorrhoids increased, and the resting pressure of the anal canal increased. More than one-third of patients have super slow waves (amplitude>625px H2O). Patients with super slow waves have higher anal resting pressure than none, suggesting that IS is overactive or abnormal contraction, which may be some hemorrhoids The pathogenic factors of the patient. Leicester, Nicholls and Thomson also noticed that when the anoscope was inserted, the resting pressure of the anus returned to normal. It may be due to the anal expansion effect of the anal mirror, which relieves the oppressive stimulation of the hypertrophic anal cushion. Read (1982) also noted that after hemorrhoidectomy, whether the anus was enlarged or not, the resting pressure of the anus was significantly reduced and the super slow wave disappeared. They assumed that the increased IS activity of hemorrhoid patients before surgery is not so much the result of the existence of hemorrhoids, but rather the cause. Hancock-Smith (1975) implemented the Lord's method to obtain satisfactory results for most patients. Its purpose is to destroy IS fibers to reduce IS activity. Roaver (1989) used IS lateral resection to treat 111 patients with stage IV hemorrhoids with a success rate of 95%.
Teramoto, Parks, and Swash (1981) found through histological observation that the external sphincter (ES) type Ⅰ and type Ⅱ fibers of hemorrhoid patients had different degrees of hypertrophy, and the number of type Ⅰ fibers increased, indicating that the patients’ ES had excessive labor load and this Correspondingly, patients have higher resting pressure of the anus and abnormal ES contractions. It is suggested that the stimulation of internal anal hemorrhoids leads to the reflex activity of pelvic floor muscles. Due to the increased tension of ES and IS, the blood flow in the anal cushion is blocked, resulting in congestive hypertrophy of the anal cushion. Not only patients with constipation, but even patients with diarrhea, the detection rate of hemorrhoids can be as high as 41.5%. This is because of the patients. In order to prevent fecal overflow, the contraction time of the sphincter is prolonged.
Sun (1990) pointed out that high-pressure anal cushion tissue is also the cause of high-pressure anal canal in patients with hemorrhoids. The measurement confirmed that the internal pressure of the anal cushion at rest is close to normal venous pressure or capillary pressure; the internal pressure of the hypertrophic anal cushion is much higher than that of normal people. Because the hypertrophy of the anal cushion produces resistance in the anal canal during defecation, it can only be overcome by intra-abdominal pressure, resulting in increased internal rectal pressure. The harder you defecate, the higher the intravascular pressure in the anal cushion will make defecation more difficult. . When feces pass through the partially obstructed anal canal, the two produce a kind of shear force, which not only affects the return of blood in the anal cushion, causing more serious congestion, but also elongates and tears the supporting tissue of the anal cushion, thereby making the anal cushion From intermittent prolapse to continuous prolapse, once the hemorrhoids prolapse, the pressure of the anal canal drops to near normal, which proves that it is feasible to use injection, band ligation, electrocoagulation or surgical resection to reduce the anal cushion. .
In summary, changes in pelvic floor dynamics are closely related to the occurrence of hemorrhoids, and the two are causal to each other. Long-term or repeated increase in intra-abdominal pressure, exceeding the physiological limit of pelvic floor muscle load, may cause the levator ani muscle to decrease → muscle fibers and nerves are elongated → nerve fiber diameter decreases → excitement conduction velocity slows → anus Abnormal contraction of meat → congestive hypertrophy of the anal pad. The hypertrophy of the anal cushion in turn stimulates the anal wall, causing ES and IS reflex contractions, and aggravating the work load of the sphincter. The increase in anal pressure causes the anal cushion to become more hypertrophic. Such a vicious circle makes the condition worse. Therefore, the incidence of hemorrhoids is higher in women who have long-term excessive bowel movements or women who have given birth to pregnancy.
In summary, the anal pad has a special mucosal epithelium, abundant arteriovenous anastomosis, and a large number of Treitz muscle fibers. It is a normal anatomical entity of the human body. Its main function is to assist the sphincter to close the anus. The modern concept of hemorrhoids believes that changes in pelvic floor dynamics, Treitz muscle degeneration, and dysregulation of arteriovenous anastomosis in the anal cushion can lead to hypertrophy or prolapse of the anal cushion.