Hematochezia

　　First, the cause of the disease

　　1. There are many diseases that can cause hematochezia. Now, according to the nature of the bleeding lesions, the causes of hematochezia are divided into 5 major categories:

　　(1) Inflammatory and ulcerative factors: When the mucosa of the lower digestive tract is inflamed or ulcerated, hematochezia can occur due to mucosal congestion, edema, and ulcer formation. When inflammation or ulcers erode blood vessels or increase vascular permeability, small blood vessels can rupture, leading to hematochezia. Common diseases include:

　　(2) Intestinal infectious diseases: Common ones include bacterial dysentery, amebic dysentery, fungal enteritis, pseudomembranous enteritis, intestinal tuberculosis, colonic tuberculosis, intestinal hookworm infection, schistosomiasis of the colon, hemorrhagic necrotizing enterocolitis, etc.

　　(3) Inflammatory bowel disease: Such as Crohn's disease or ulcerative colitis.

　　(4) Radiation colitis and proctitis: It is usually caused by local mucosal damage to the intestines after radiotherapy for pelvic malignant lesions, leading to bleeding, often manifested as recurrent, small amounts of hematochezia.

　　(5) Ischemic colitis: It is more common in elderly patients with atherosclerosis, caused by impaired blood supply to the mesentery, leading to ischemia of the intestinal mucosa and the formation of ulcers. The lesions are most common in the colon, and the clinical manifestation is dark red or bright red stools after severe abdominal pain.

　　(6) Behcet's disease: The etiology of this disease is unknown, and it is generally believed that immunovascular inflammation causes vascular occlusion, leading to intestinal ischemia and ulcerative lesions; some scholars also believe that the disease is related to infection or heredity. Ulcers occurring in the ileocecal region are most common and are prone to bleeding.

　　(7) Rectal or solitary ulcer: The cause of this type of ulcer is not clear, but bleeding can occur when the ulcer erodes blood vessels.

　　(8) Colonic stress ulcer: In recent years, it has been found that taking non-steroidal anti-inflammatory drugs (NSAIDs) can lead to hematochezia, even massive hemorrhage, and it is more common in middle-aged and elderly patients.

　　(9) Inflammation and ulcerative lesions are common causes of hematochezia. Most inflammation and ulcers in the rectum and sigmoid colon can cause mucopurulent stools; severe ulcerative colitis and schistosomal granuloma can cause bright red stools; amebic dysentery often causes jam-like or dark red stools; a few cases of intestinal tuberculosis or Crohn's disease can lead to massive hemorrhage; hemorrhagic necrotizing enterocolitis often excretes dark red, bright red, or meat water-like stools. In summary, the amount and color of hematochezia are often related to the size, location, and bleeding speed of the lesions.

　　2, Hemorrhagic factors due to vascular lesions in the lower gastrointestinal tract, leading to vessel rupture or causing mesenteric vascular ischemia and obstruction of blood supply to the intestinal mucosa. Common causes include:

　　(1) Arteriovenous malformations and maldevelopment of vessels: Hemorrhage caused by vascular maldevelopment and malformations in the intestinal wall of the lower gastrointestinal tract has attracted attention in the past 10 years and has become one of the important causes of hematochezia. It can be divided into:

　　① Cavernous hemangioma.

　　② Maldevelopment of submucosal vessels in the intestinal mucosa.

　　③ Vascular malformations. About 70% of the lesions occur in the colon, among which the right half colon or cecum is more common. A small number of vascular malformations occur in the small intestine.

　　(2) Hereditary hemorrhagic telangiectasia (Rendu-Osier-Weber syndrome): This syndrome can occur throughout the gastrointestinal tract, and it is more likely to cause bleeding when it occurs in the small intestine. This disease is rare and belongs to a familial hereditary disease.

　　(3) Dieulafoy's disease: The most common site of the lesion is in the stomach, and if it occurs in the small intestine or colon, it can cause hematochezia. This disease is more common in middle-aged and elderly patients, and bleeding is often caused by the rupture of submucosal vessels due to inflammation and ulceration.

　　(4) Submucosal varices of the rectum, colon, and small intestine: In patients with portal hypertension, after the establishment of collateral circulation, a small number of patients may have varices in the submucosal veins of the ileum and colon, and if they rupture, they can cause hematochezia. After the operation of splenectomy and transverse transection of the gastric fundus vessels, varices in the submucosal veins of the ileum are more likely to occur.

　　(5) Hemorrhoids in long-distance or endurance athletes: In recent years, it has been found that diseases caused by long-distance or endurance athletes are increasing, such as marathon runners. In addition to a few cases that can cause skeletal, muscular, and cardiac lesions, gastrointestinal lesions have also been reported, which can manifest as hematochezia. The cause of hematochezia is not only related to the rupture of hemorrhoids but also related to the impact, vibration of abdominal visceral organs, and redistribution of blood causing intestinal ischemia (immediate colonoscopy should be performed for athletes with hematochezia, which can find changes such as hyperemia of the intestinal mucosa, accompanied by erosion and bleeding foci).

　　(6) Wegener's granulomatosis: It is an idiopathic systemic vasculitis disease, often with lesions in the nasopharynx, lungs, and necrotizing glomerulonephritis. The disease can sometimes involve the gastrointestinal tract, causing ischemia and bleeding in the small intestine or colon, and in severe cases, intestinal perforation may occur.

　　(7) Ischemic lesions of mesenteric vessels can be seen in:

　　① Spasm of mesenteric vessels.

　　② Formation of mesenteric venous thrombosis.

　　③ Mesenteric artery embolism.

　　④ Ischemic colitis. Ischemic lesions of mesenteric vessels can be caused by shock, atherosclerosis, endarteritis, or secondary to heart diseases with atrial fibrillation (ischemic colitis has been mentioned in the inflammatory and ulcerative factors).

　　(8) Abdominal aortic aneurysm: If an abdominal aortic aneurysm ruptures and penetrates the small intestine or large intestine, it can lead to massive lower gastrointestinal bleeding.

　　(9) Internal and external hemorrhoids: When internal and external hemorrhoids bleed, it is usually accompanied by blood on the surface of feces or bleeding after defecation. However, in a few cases, after internal hemorrhoids bleed, the blood may accumulate in the rectal ampulla, and when the blood is discharged all at once, it may manifest as dark red or bright red fecal blood. Hemorrhoid bleeding is also one of the common causes.

　　3. Mechanical factors

　　(1) Jejunal diverticulum: Bleeding occurs due to inflammation within the diverticulum.

　　(2) Colonic diverticulum or diverticulosis: Colonic diverticulosis has become one of the important causes of hematochezia in Western and European countries, but it is relatively rare in China.

　   (3) Meckel diverticulum: It often occurs at the distal ileum, 70% to 85% of patients may be asymptomatic, but those with symptoms commonly present with bleeding.

　　(4) Intussusception or intestinal volvulus: Intussusception is more common in infants under 10 years old, and more than 60% of adult intussusception is secondary to multiple colonic polyps or intestinal tumors. Prolonged intestinal volvulus can lead to bleeding due to intestinal ischemia.

　　(5) Intussusception of ileocecal valve: In some cases, such as intussusception of the ileocecal valve or adhesion, bleeding can occur.

　　(6) Endometriosis in the colon: When endometrial tissue is located in the colonic mucosa, blood in the stool can occur in female patients during menstruation, and the hematochezia will stop at the end of the menstrual cycle.

　　(7) Anal fistula and anal fissure: In some cases, anal fistula and anal fissure can cause bleeding, but the amount of bleeding is usually not large.

　　(8) After polypectomy under colonoscopy, or after small and large bowel surgery: If the coagulation is not sufficient during polypectomy, it can lead to bleeding at the coagulation surface. Inadequate hemostasis during intestinal surgery can also cause bleeding.

　　4. Under the condition of tumor factors, there are many benign and malignant tumors in the digestive tract, which are one of the important causes of bleeding.

　　(1) Benign tumors:

　　(1) Benign tumors: include familial adenomatous polyposis, Gardner syndrome, Turcot syndrome, juvenile polyps, melanotic macule-gastrointestinal multiple polyps (P-J syndrome), hyperplastic polyps, inflammatory polyps, and other conditions. They are one of the important causes of hematochezia.

　　② Small intestine leiomyoma, neurofibroma, and other rare conditions.

　　(2) Malignant tumors:

　　① Small intestine malignant lymphoma: It can sometimes present with massive hemorrhage.

　　② Small intestine adenocarcinoma: It is relatively rare.

　　③ Small and large intestine carcinoid tumors: Hemorrhage caused by these tumors is relatively rare.

　　④ Colonic and rectal cancer: It is one of the common causes of hematochezia, but the amount of bleeding is usually small.

　　5. Systemic diseases

　　(1) Infectious diseases: typhoid fever, paratyphoid fever, epidemic hemorrhagic fever, leptospirosis, severe hepatitis, or fulminant hepatic failure, and other diseases.

　　(2) Hematological diseases: hemophilia, abdominal type Henoch-Schönlein purpura, gastrointestinal type malignant histiocytosis, and other diseases.

　　(3) Connective tissue diseases: nodular polyarteritis (pericolic nodular arteritis of the colon), systemic lupus erythematosus, and rheumatoid arthritis can involve the intestines.

　　(4) Other causes: severe sepsis, food poisoning, mercury poisoning, uremia, and other conditions can all cause hematochezia.

　　In general, children and adolescents with hematochezia are commonly caused by colonic polyps, intussusception, Meckel diverticulum, and inflammatory diseases; middle-aged and elderly patients are more likely to have intestinal inflammatory lesions, colonic cancer, rectal cancer, and intestinal vascular lesions as the causes; perianal lesions such as hemorrhoids, anal fissures, or fistulas should not be ignored in adults.

　　Secondly, pathogenesis

　　1. Lower gastrointestinal diseases

　　(1) Anal canal diseases: Hemorrhoids are caused by increased intra-abdominal pressure during defecation, leading to increased blood pressure in the hemorrhoidal plexus, plus direct abrasion by hard fecal masses causing hemorrhoids to rupture. Anal fissures can be seen in children due to pinworm infection causing perianal itching, infection from scratching, and forming after defecation, with severe pain and hematochezia during defecation, with small amounts of bright red blood. Anal fistula is most commonly secondary to perianal and rectal abscesses, and a few are secondary to intestinal tuberculosis. Anal fistula orifices can be seen near the anus, perineum, or sacral tail, and pus can be seen flowing out of the fistula orifice when the surrounding area is compressed.

　　(2) Intestinal inflammatory diseases: Such as acute bacterial dysentery, acute hemorrhagic necrotizing enteritis, intestinal tuberculosis, ulcerative colitis, etc., all caused by different etiologies leading to congestion, edema, erosion, ulceration, hemorrhage, and even necrosis of the intestinal mucosa in different parts. Manifested as purulent blood in the feces, bloodwater stools, or even fresh blood in the stools.

　　(3) Intestinal tumors: Colon cancer, rectal cancer, small intestinal malignant lymphoma, etc., mainly due to ulceration of the cancer tissue or lymphoma tissue, resulting in bright red stools or stools mixed with mucus and pus. Benign small intestinal tumors, such as small intestinal neurofibroma, leiomyoma, adenoma, etc., have less bleeding, but large tumors can cause intestinal obstruction. Infection and rupture of small intestinal hemangioma can cause acute massive hemorrhage.

　　(4) Lower gastrointestinal vascular lesions, such as mesenteric artery occlusion or mesenteric arteriovenous thrombosis, intussusception, volvulus, etc., due to ischemia, necrosis, and shedding of the intestinal mucosa, cyanosis, edema, and a large amount of serous exudation in the intestinal tract, necrosis of the entire thickness of the intestinal wall, and a large amount of hemorrhagic fluid exudation, can lead to diarrhea with dark red blood in the feces.

　　2. Pathogenesis of systemic diseases is similar to upper gastrointestinal bleeding (vomiting blood and black stools).

　　1. Hematochezia with blood mixed with feces, frequent urination, incomplete defecation sensation, abnormal defecation frequency, tenesmus. Diarrhea, fever accompanied by abdominal pain, diarrhea, nausea, vomiting, mucoid stools, abdominal pain accompanied by nausea and vomiting, abdominal pain accompanied by diarrhea, nausea, nausea and watery stools, purulent blood in feces.

　　1. Dry lips and mouth, thirst for cold drinks, swollen gums, halitosis, bitter taste in the mouth, aphthous ulcers on the tongue, constipation, burning sensation at the anus, red tongue with yellow fur, rapid and strong pulse. Damp-heat syndrome: Hematochezia followed by defecation, bright red blood, unsmooth defecation, limb weakness and epigastric distension, loss of appetite, bitter taste in the mouth, dark red urine, red tongue with greasy yellow fur, soft and rapid pulse.

　　1. Fresh blood in feces

　　Mostly acute (immediate) bleeding, where blood flows out of the vessels for a short time and is excreted with feces through the anus, or it may be directly discharged after defecation. The appearance of the discharged blood resembles that of traumatic bleeding, with bright red, purple-red, or dark red color, which can coagulate into blood clots after a while. It often occurs in the following diseases:

　　(1) Hemorrhoids: Hemorrhoids in all stages, both internal and external, and mixed hemorrhoids can cause hematochezia, usually manifested as fresh blood on the feces or bleeding after defecation. External hemorrhoids generally do not cause hematochezia.

　　(2) Intestinal polyps: Characterized by painless hematochezia during defecation. The bleeding stops after defecation, with varying amounts of blood, usually not mixed with feces, or may be mixed with feces if the polyps are located high up or in large numbers.

　　(3) Rectal prolapse: After a long illness, there may be bleeding during defecation.

　　(4) Anal fissure: Hematochezia, with blood stains on one side of the stool surface, not mixed with stool, and some patients may have blood droplets after defecation.

　　2, Pus/mucus blood stool

　　That is, the stool excreted contains both pus (mucus) and blood. Pus (mucus) blood stool is often seen in tumors and inflammation in the rectum or colon. Common diseases include the following:

　　(1) Rectal cancer: The color of blood is fresh or dark red, and there may be mucus in the stool, often mixed with blood, mucus, and stool.

　　(2) Colon cancer: With the extension of the course, there will be defecation with blood, mostly containing pus or mucus, and the color of blood is darker.

　　(3) Ulcerative colitis: Mucous stool or purulent stool, accompanied by left lower abdominal pain or lower abdominal pain.

　　(4) Gastrointestinal infectious diseases: Such as bacterial dysentery, amebic colitis, etc.

　　3, Black stool

　　Also known as tarry stool, stool is black or brown. It is one of the most common symptoms of upper gastrointestinal bleeding. If the amount of bleeding is small and the speed is slow, and the blood stays in the intestine for a long time, the stool excreted will be black; if the amount of bleeding is large and the time in the intestine is short, the blood excreted will be dark red; if the amount of bleeding is particularly large and excreted quickly, it can also be bright red.

　　4, Occult blood stool

　　Small (trace) gastrointestinal bleeding does not cause a change in stool color, but only shows positive in occult blood test in stool, known as occult blood stool. All diseases causing gastrointestinal bleeding can cause occult blood stool, common ones include ulcers, inflammation, and tumors. Occult blood test in stool can detect small (trace) blood components in stool. Early occult blood in stool of intestinal polyps (cancer) can show positive, regular stool occult blood test is an important way for colorectal tumor screening (initial screening).

　　5, Accompanying symptoms

　　(1) Anal and perianal lesions: Hematochezia is bright red, with severe anal pain, or swelling with hemorrhoids, or accompanied by anal fissure.

　　(2) Upper gastrointestinal diseases: Hematemesis is usually accompanied by melena, and blood in the stool can occur when the amount of bleeding is large and the speed is fast.

　　(3) Lower gastrointestinal diseases: The symptoms vary according to the primary disease causing bleeding.

　　Preventive work should start from daily life. Maintain smooth defecation, prevent and treat constipation by eating vegetables rich in fiber such as chives, celery, cabbage, spinach, etc., and fruits with bananas being the best. Drink a moderate amount of cool water in the morning, have a good breakfast, which helps defecation; live a regular life, defecate at a fixed time every day, keep the anal area clean, do not squat for a long time or exert excessive force during defecation; participate in appropriate physical activities.

　　In the early stage after hematochezia, there may be no significant changes in hemoglobin and red blood cell count, but after the administration of isotonic fluid and expansion of blood volume, the determination of red blood cell count, hemoglobin, and hematocrit can help in judging the amount of blood loss, and the degree of increase in blood urea nitrogen is also beneficial for judging the amount of bleeding (known as intestinal origin of increased blood urea nitrogen).

　　2. If the red blood cell count, hemoglobin, and hematocrit no longer decrease progressively, or blood urea nitrogen returns to normal, it indicates that bleeding has stopped.

　　3. X-ray barium meal or barium enema examination, gas-barium double contrast examination for duodenum, jejunum, ileum examination, or total colon examination, is of great help in the diagnosis of diseases such as intestinal tuberculosis, Crohn's disease, schistosomiasis, ulcerative colitis, intestinal torsion, intussusception, polyps, or cancer.

　　4. Sigmoidoscopy or total colonoscopy examination is very helpful for the diagnosis of diseases such as inflammation, polyps, or cancer in the rectum and sigmoid colon, which are common sites of inflammatory lesions. Total colonoscopy examination can not only find the above diseases but also help in the diagnosis of hemorrhagic lesions in the descending colon, transverse colon, ascending colon, and cecum. If the colonoscope enters the terminal ileum, it can also provide help for the diagnosis of lesions such as tuberculosis, Crohn's disease, and lymphoma at the terminal ileum. If combined with biopsy and histological examination, it can significantly improve the accuracy of diagnosis.

　　5. Abdominal B-ultrasound or CT, MRI examination has auxiliary diagnostic value for medium and late-stage colon cancer. If there is enlargement of abdominal or retroperitoneal lymph nodes, it has reference value for the diagnosis of diseases such as intestinal tuberculosis and lymphoma.

　　6. When performing selective angiography for hematochezia, selective superior and inferior mesenteric artery catheter angiography can be performed to clearly identify the bleeding site, which is also conducive to the diagnosis of vascular malformations and other diseases. Therefore, for patients with hematochezia of unknown cause, selective angiography is an indispensable examination to determine the bleeding site or etiology.

　　7. Wireless capsule endoscopy (wireless capsule endoscope) examination: In recent years, wireless capsule endoscopy (also known as capsule endoscopy) has begun to be applied in clinical practice. This examination is non-invasive, and all patients can tolerate it without any adverse reactions. The capsule is slightly larger than a common medication capsule, containing a flash device and a photochip. The capsule takes about 40 minutes to reach the pylorus after swallowing; on average, it takes 350 minutes to examine the gastrointestinal tract. When the capsule passes through the gastrointestinal cavity, the images it captures are stored in a computer through a remote receiver in the abdomen, and then each clear image is analyzed one by one. The capsule endoscope is finally excreted with the feces through the rectum and colon (it is a disposable product). Some scholars believe that after cleaning the intestines, swallowing the capsule endoscope has more advantages, which is conducive to obtaining the accurate stopping time of the capsule passing through multiple parts, thereby determining the exact location of the lesion. The sensitivity and accuracy of this examination are higher than those of the barium meal examination of the small intestine, but sometimes it cannot accurately locate the lesion or perform biopsy on the lesion, which is the main defect of the capsule endoscope. According to foreign data, the positive diagnostic rate of capsule endoscopy for occult gastrointestinal bleeding can reach more than 80%. It can make a diagnosis of various lesions such as vascular malformations, polyps, tumors, Crohn's disease, ulcers, celiac disease, etc. Therefore, some scholars in foreign countries believe that for patients with gastrointestinal bleeding, capsule endoscopy should be the first choice when routine examinations are negative. However, in China, due to its high examination cost, its popularization and development is still limited to a certain extent.

　　8, The new pushenteroscope (pushenteroscope P.E) examination The new type of pushenteroscope has been applied in clinical practice, and it can perform histological examination at the lesion site. It is said to be of great value in the diagnosis of difficult-to-diagnose small intestinal diseases. The new pushenteroscope overcomes the disadvantages of the old pushenteroscope, such as the difficulty in passing through the junction of the duodenum and jejunum (flexure ligament).

　　1, Avoid drinking

　　Hemorrhoids are mostly due to damp-heat, and drinking can exacerbate this damp-heat. Moreover, alcohol (especially strong alcohol) can cause congestion in the rectal veins, triggering or aggravating hemorrhoids.

　　2, Avoid food with strong flavors and a lot of spices

　　It can easily cause discomfort in the intestines, and at the same time, it can cause congestion in the liver and increase the pressure in the lower abdominal cavity, which may lead to the occurrence or exacerbation of hemorrhoids.

　　3, Avoid rich, sweet, and greasy food as well as roasted food

　　These foods can stimulate the mucous membrane and skin of the rectum and anal area, causing obvious congestion and leading to the occurrence of hemorrhoids.

　　4, Avoid fruits that enhance yang fire

　　Such as mango, durian, lychee, longan, etc.

　　5, Avoid difficult-to-digest and hard food

　　Difficult-to-digest food can lead to constipation, which in turn causes varicose veins in the rectum.

　　6, Avoid spicy and刺激性 food

　　Spicy and刺激性 food, such as chili, pepper, scallion, garlic, mustard, ginger, etc., can stimulate the blood vessels in the rectum and anal area to become congested and dilated, causing pain and a feeling of sagging during defecation, thus triggering hemorrhoids.

　　Patients with hematochezia, especially with massive lower gastrointestinal bleeding, should carefully analyze the possible causes of bleeding based on their medical history, clinical manifestations, and characteristics of the bleeding. At the same time, effective hemostatic measures should be taken immediately to achieve hemostasis as soon as possible, thus creating conditions for further searching for the etiology of bleeding. The following treatment principles should be followed during hematochezia.

　　1. General treatment measures In cases with hemorrhagic shock, patients should rest in bed, lie flat without a pillow, and receive oxygen. Strictly observe vital signs such as consciousness, respiration, pulse, blood pressure, and also observe the amount and color of stool bleeding, and record urine output.

　　2. Compensate for blood volume In cases with large amount of blood in stool, obvious anemia, or shock, it is necessary to actively compensate for blood volume. Plasma substitutes or whole blood are preferable, which is beneficial for correcting shock.

　　3. Use hemostatic drugs

　　(1) Repeated enema with 6% to 8% norepinephrine (adrenaline) solution or repeated enema with ice water (not suitable for frequent use in winter), in addition to stopping bleeding, can also clean the intestines, thus preparing for colonoscopy.

　　(2) Coagulation enzyme or herbal medicine such as Baiyao or Baiji powder dissolved in physiological saline for enema, which can sometimes also have a hemostatic effect.

　　(3) Intravenous administration of routine hemostatic drugs, such as phenolsulfonate (hemostatic agent), vitamin K1, aminomethylbenzoic acid (antifibrinolytic acid), 6-aminohexanoic acid, or thrombin (Stop bleeding) and others.

　　(4) Those who have the condition can transfuse cold sediment (containing various coagulation factors) or platelets and other coagulation components.

　　(5) When performing selective (or superselective) arteriography of the superior or inferior mesenteric artery, if the bleeding site is found, pituitrin or terlipressin can be injected into the bleeding vessel, and the effective hemostasis rate can reach 80% to 90% or more.

　　4. Actively identify the bleeding site or cause

　　(1) Selective arteriography of superior and inferior mesenteric arteries: This examination can be performed during the bleeding process. It is of great help in identifying the bleeding site and sometimes can also clarify the cause.

　　(2) Colonoscopy: Colonoscopy can be performed after basic hemostasis. It is of diagnostic value for the lesions of the entire colon (including the ileocecal junction and the distal ileum), and the rectum. After finding the bleeding site, various hemostatic methods can be used under the endoscope.

　　(3) Barium X-ray examination: Barium enema or barium灌肠造影 can be performed after bleeding stops to assist in finding the primary diseases that cause bleeding.

　　(4) Capsule endoscopy or a new type of small bowel endoscopy can be performed for difficult cases to clarify the diagnosis as soon as possible.