Colonic diverticula

Introduction The colonic diverticulum is a colon wall that protrudes outward to form a pocket. It can be a single, but more of a series of saclike protrusions that are outward from the lumen of the intestine. Colonic diverticula can be divided into two categories: true and acquired. The true diverticulum is a congenital full-thickness of the colon wall, and the diverticulum contains layers of the intestinal wall. The acquired diverticulum is the mucosa that is excreted through the weak points of the muscular layer of the intestinal wall, so it is secondary to the increase in pressure in the intestinal lumen, forcing the mucosa to protrude outward through the weak area of the muscle of the intestinal wall.

Cause

1. Congenital factors. Evans suggested that congenital right colon diverticulosis may be due to abnormal embryonic development of the intestinal wall. Waugh believes that the cecal diverticulum is caused by overgrowth of the cecum at 7-10 weeks of embryonic development. Normally, the development of this part should be atrophic. Some patients with colonic diverticulosis have a family history. Most of the diverticulosis is caused by acquired diseases. The histological study did not find congenital abnormalities in the muscular wall of the colon wall. The increase in the incidence of diverticulosis with age also provides strong evidence for this. The congenital colonic diverticulum is rare.

2. Acquired factors. Some scholars believe that the low-fiber diet in western developed countries is the main cause of diverticulosis. The following clinical findings can confirm:

1 The incidence rate has obvious geographical distribution characteristics;

The incidence rate gradually increased after the 1950s;

3 The incidence of diverticulum changes after dietary changes in the mobile population;

4 Incidence increases with age;

5 high-fiber diet can prevent diverticulosis.

(1) Factors affecting the formation of diverticulum: one is the tension of the colon wall, and the other is the pressure difference between the colon cavity and the abdominal cavity. The intracavity pressure at any location can be determined by Laplace's pressure law. Laplace's law of pressure (P = kT / R, P is the pressure in the colon cavity, T is the tension of the intestinal wall, R is the radius of the colon, k is a constant) Description: The pressure in the intestinal lumen is proportional to the tension of the intestinal wall, and the radius of the intestinal wall In inverse proportion. Recently, pressure gauge studies have shown that the colon, especially the sigmoid colon, can produce high intraluminal pressure during continuous segmental motion. The largest intraluminal pressure in the colon is located in the descending colon and the sigmoid colon. This pressure is sufficient to cause the mucosa to protrude from the colon muscle to form a diverticulum.

(2) Structural features of the colon wall: may also be a factor in the incidence of diverticulum. The collagen fibers in the colonic ring muscle are cross-distributed, which maintains the tension of the colon wall. As the age increases, the collagen fibers inside the colon cavity become thinner, the action of elastin fibers decreases, and the elasticity and tension of the colon wall decrease. Therefore, the narrowest and most hypertrophic sigmoid colon is a predilection site for the diverticulum. The muscles of the colonic band are in a contracted state, so the diverticulum is less likely to occur. It has been confirmed that the sigmoid smooth muscle muscle bundle of the diverticulum patient is thicker than normal. Even without the formation of a hypertrophic smooth muscle bundle, the abnormal smooth muscle bundle is a manifestation of the early diverticulum. Abnormal smooth muscle bundles are not limited to the sigmoid colon, but can also be found in other parts of the colon, such as the upper rectum. This is more pronounced after sigmoid resection. In the early stages of the disease, these weak points in the colon wall have been shown. In addition, connective tissue disorders caused by structural protein changes play a role in the early stages of diverticulosis.

(3) Colonic movement: divided into two types: rhythmic contraction and propelled contraction. The former mainly mixes the contents of the right colon to the back and forth to promote the absorption of water and salt. The latter transports the feces distally. Mass peristalsis can cause feces to be pushed directly from the right colon to the sigmoid colon and the upper rectum. The colonic diverticulum is prone to occur on the weak intestinal wall between the colonic bands. When the intraluminal pressure increases during segmental motion, these potentially weak sites tend to form diverticulum where the blood vessels enter the colon wall.

(4) Compliance of the intestinal wall: Abnormality of the intestinal wall may also be the cause of the diverticulum. The study of the dynamics of the colon in resting and stimulating states supports this view. Eastwood et al. found that symptomatic colonic diverticulum patients showed excessive abnormal colonic stress responses to certain drugs, food, and dilated balloons. Normally, the intracavity pressure and volume are linear (Figure 5). However, the pressure in the diverticulum patient quickly reached a stable period, and the pressure remained stable even as the volume increased. The threshold of stress response in diverticulum patients is significantly lower than that in normal people. The cause of decreased colon wall compliance may be related to hypertrophic smooth muscle and structurally disordered collagen fibers.

(5) Pressure in the colon cavity: The baseline pressure of the diverticulum patient was found to be significantly higher than that of the normal person. When the pressure in the sigmoid colon is abnormally increased, the patient may experience pain and discomfort in the left armpit and delayed bowel movement. The myoelectric frequency of diverticulum patients is 12 to 18 Hz, which is higher than that of normal people (6 to 10 Hz). The colonic EMG of the diverticulum patient is different from the irritable bowel syndrome, and the relationship between the two is still not obvious. Patients with diverticulum with pain often have intestinal irritation syndrome, and the underlying pressure of such patients tends to increase. After the diverticulum patient was fed, given neostigmine or morphine, the colonic motor index was significantly higher than normal. Dingding does not increase the internal pressure of the sigmoid colon, and prufenin and bran can reduce the intracolonic pressure. Abnormal pressure in resting and stimulating conditions does not improve after resection of the sigmoid colon, suggesting a complete colonic dysfunction.

In short, the cause of diverticulum remains to be elucidated, which may be the result of colonic smooth muscle abnormalities, increased intracavitary pressure during segmental contraction, decreased compliance of the intestinal wall, and low-fiber diet.

3. Relevant factors

(1) Obesity: Obesity has been thought to be related to diverticulosis in the past, but studies have confirmed that this is not the case. Hugh et al found that subcutaneous fat thickness was not associated with the incidence of diverticulum.

(2) Cardiovascular disease: There is no correlation between hypertension and diverticulosis, but the incidence of diverticulum in patients with atherosclerosis is increased, which is presumed to be related to ischemia of the inferior mesenteric artery. In male patients with previous myocardial infarction, the incidence of diverticulum was 57%, which was significantly higher than that of male patients in the same age group (25%). The incidence of diverticulum was significantly higher in patients aged 65 years and older with cerebrovascular accidents than in the control group.

(3) Emotional factors and irritable bowel syndrome: No psychological and emotional factors were found to be associated with diverticulosis, which is different from irritable bowel syndrome. There are many similarities between irritable bowel syndrome and diverticulosis (such as stool weight, fecal bile acid and fecal electrolyte content). The former's intestinal base pressure is also increased, and both often exist simultaneously. EMG examination has both rapid wave appearance, excessive stress response to food and neostigmine stimulation, and high fiber diet can correct the abnormal delivery time, increase stool weight, and reduce intestinal pressure. . It is generally believed that inhibition of venting and defecation increases intra-intestinal pressure and promotes diverticulum formation, but this is not the case. Because the young people's sphincter function is very strong, the incidence of diverticulum is not high. The elderly with rectal sphincter relaxation are more frequent. In addition, patients with megacolon and constipation were found to have diverticulum.

(4) Intestinal inflammatory diseases: The relationship between intestinal inflammatory diseases and diverticulosis is complicated. Patients with diverticulum have an increased intracolonic pressure with ulcerative colitis. About 2/3 of patients with diverticulosis and Crohn's disease developed perianal symptoms such as ulcers and lower fistulas. The incidence of Crohn's disease complicated with diverticulum is five times higher than that of normal people. The main clinical features are pain, incomplete intestinal obstruction, abdominal mass, rectal bleeding, fever and leukocytosis. Berridge and Dick used radiology to study the relationship between Crohn's disease and colonic diverticulosis, and found that when Crohn's disease gradually developed, diverticulosis gradually "disappeared"; conversely, when Crohn's disease gradually eased, diverticulosis reappeared. This peculiar phenomenon is prone to inflammatory masses, abscesses and fistulas and other complications, especially in the elderly are more likely to form granuloma. Radiological examination showed that the mucosa of the diverticulum was intact except for abscesses and stenosis, and mucosal ulcers and edema of Crohn's disease (Fig. 7). Fabriaus et al found that Crohn's disease on the left side often coincided with diverticular disease.

(5) Others: Diverticulosis is associated with biliary tract disease, hiatal hernia, duodenal ulcer, appendicitis and diabetes, often accompanied by hemorrhoids, varicose veins, abdominal wall hernia, gallstones and hiatus hernia. Small sample studies found no significant relationship between diverticulosis and duodenal ulcer and arterial disease. Case-control studies have found that ingestion of non-steroidal anti-inflammatory drugs is prone to severe diverticulum complications.

(6) Nodules and rectal malignant tumors: The relationship between diverticulosis and knots, rectal polyps and tumors remains unclear. Edwards found that patients with diverticulum had a lower incidence of malignant tumors and benign adenomas than the general population, and rarely had polyps and colorectal cancer.

an examination

Related inspection

Colonoscopy

Correct diagnosis is an extremely important part of judging the condition and determining the treatment policy. Some patients with mild symptoms and signs of diverticulitis can be successfully treated in outpatient conditions, while others with acute life-threatening conditions require emergency resuscitation and life-saving surgery. Therefore, the most important assessment is clinical examination and frequent repeated examination of patients. This includes not only medical history and physical examination, pulse and body temperature, but also continuous blood test, abdominal upright position and flat-lying X-ray. The diagnosis of left colonic diverticulitis is simple when all typical symptoms and signs are present. In these cases, no auxiliary examination is needed, and treatment should be based on the diagnosis. Unfortunately, most cases are often unclear, and the severity of the diagnosis and seizure may not be clear after the initial clinical examination. Only 7% of patients with acute right colonic diverticulitis who had a correct diagnosis before surgery. Preoperative studies are generally unhelpful and can only delay proper treatment.

Three tests were helpful in determining the clinical diagnosis of acute left colonic diverticulitis and the presence of significant inflammatory complications. This is endoscopic, gas-filled double contrast enema, and abdominal and pelvic CT scans. Endoscopy should generally be avoided in acute situations, as perforation may induce perforation or aggravation of existing perforations. If other straight sigmoid lesions are considered, and the disease will change the treatment, it can be used for endoscopy but should not be inflated.

Barium enema can be used to diagnose diverticulitis, but there is a risk of expectorant spillage into the abdominal cavity, which will cause severe vascular collapse and death. Hackford et al. advocated a barium enema 7 to 10 days after the inflammatory process subsided to confirm the diagnosis. If a more urgent diagnosis is needed to guide the treatment, a water-soluble contrast agent can be used to enema, so that even if the contrast agent overflows into the abdominal cavity, it will not cause a serious reaction.

CT scans are non-invasive tests that generally confirm clinically suspected diverticulitis. Rectal enhancement during scanning can make the diverticulum abscess or fistula more sensitive than X-ray. Labs et al reported that CT scans were more effective in diagnosing complications of diverticulitis: CT scans diagnosed 10 of 10 abscesses and 11 of 12 fistulas, and X-ray angiography diagnosed 2 of 8 abscesses And 3 of 8 cases of fistula. Another advantage of CT scanning is that it can guide percutaneous drainage of abscesses.

The diverticulum colonic bladder fistula is best diagnosed by CT scan. More than 90% of patients can be diagnosed clearly. It may require cystoscopy and show focal inflammatory process in the fistula. Barium enema and fiber sigmoidoscopy are not. Very effective, only about 30% to 40% of the test results are positive. Abdominal plain films can show colonic obstruction secondary to sigmoid colon lesions. A water-soluble contrast agent enema can confirm the diagnosis.

Differential diagnosis

Colonic diverticulosis should be differentiated from abnormalities of intestinal wall movement, such as irritable bowel syndrome, tumor, appendicitis, and colitis of the colon.

1. Colon cancer. Colon cancer and diverticulosis have more similarities: the incidence increases with age; can occur in any colon, sigmoid colon; clinical symptoms are similar, such as changes in bowel habits, lower abdominal pain; can cause obstruction or perforation; The clinical course is relatively insidious; both can cause bleeding. However, diverticulitis is more severe with abdominal pain, accompanied by fever and leukocytosis; colon cancer hemorrhage is occult blood positive or a small amount of bleeding, while diverticulum hemorrhage can be small, moderate or massive bleeding. About 20% of diverticulum patients have polyps or tumors. Boulos et al reported that 23% of diverticulum patients had colonic polyps, 8% of diverticulum patients had malignant colon tumors, and barium enema had a higher false positive rate for both. Forde reported that 11 of 12 patients were suspected of having tumors. Malignant tumors were excluded by sigmoidoscopy. The false positive rate of diagnosis of barium enema is 10% to 20%. The false positive rate of diagnosis of polyps is 22% to 35%. Therefore, for left colon lesions, sigmoidoscopy is the preferred method of examination.

2. Appendicitis. When cecal diverticulitis or diverticulitis of the sigmoid colon is located in the right lower abdomen, there may be symptoms similar to appendicitis, but appendicitis is more common than diverticulitis, and it is characterized by metastatic abdominal pain. The early pain of cecal diverticulitis is fixed in the right axillary fossa, not in the umbilical or upper abdomen. The pain does not start from the umbilical or upper abdomen. It is longer from the onset of symptoms to the admission (3 to 4 days), vomiting is rare, nausea and Diarrhea is more common. If appendicitis is not ruled out, surgical exploration is required. If diverticulitis is found, it is usually removed. Therefore, when the right lower quadrant pain is encountered and the cause is not clear, a CT scan can be performed to rule out diverticulitis.

3. Inflammatory bowel disease. Both colonic inflammatory disease and diverticulitis can have abdominal pain, changes in bowel habits, blood in the stool and fever. Ulcerative colitis is easy to distinguish from diverticulitis, ulcerative colitis almost all affect the rectum, so rectal microscopy can easily and accurately rule out ulcerative colitis. Both sinusitis, obstruction, and abscess can be formed in both diverticulitis and Crohn's disease. When multiple intraluminal lesions and longitudinal submucosal fistulas are found by angiography, Crohn's disease is more likely. In elderly patients with diverticulosis and Crohn's disease, it is difficult to identify, enema or endoscopy for correct diagnosis.

4. Gastrointestinal bleeding. When the diverticulum and blood is emitted, the symptoms are similar to duodenal ulcer bleeding. For example, a large amount of bright red blood is discharged through the rectum, often accompanied by hypovolemic shock performance, which should be carefully identified. Asking for medical history, physical examination, indwelling gastric tube, and gastroscopy can rule out upper gastrointestinal bleeding. Congenital vascular dysplasia, arteriovenous malformation, telangiectasia, vascular disease, etc. are the causes of lower gastrointestinal bleeding. Diverticulosis with massive hemorrhage, radionuclide scanning and colonoscopy are helpful for diagnosis, but selective mesenteric angiography is the most reliable and most diagnostic test for acute bleeding, depending on the angiography, distribution, contrast agent spillage and Intestinal tube visualization determines the location of the lesion and distinguishes between diverticulum, tumor and vascular malformations.

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