Disease Description
Intestinal tuberculosis is a chronic, specific infection of the intestinal tract caused by Mycobacterium tuberculosis and is one of the most common forms of extrapulmonary tuberculosis. It is mainly caused by Mycobacterium tuberculosis of human type. In a few areas, bovine Mycobacterium tuberculosis intestinal tuberculosis has occurred as a result of drinking unpasteurized sterile milk or dairy products. The disease is usually seen in young and middle-aged people, with slightly more women than men.
Etiology and pathogenesis
Intestinal tuberculosis is generally caused by human tuberculosis bacilli, but occasionally bovine tuberculosis develops from the consumption of bacteriophage milk or dairy products.
I. Gastrointestinal infection
The main mode of infection of intestinal tuberculosis is the patient’s original open tuberculosis, secondary to infection by swallowing sputum containing tuberculosis bacilli; or frequent close contact with tuberculosis patients. The primary intestinal tuberculosis can be caused by neglecting sterilization and isolation measures. After being ingested, M. tuberculosis is mostly not killed by gastric acid because of its lipid-containing outer membrane. When the bacilli reach the intestine (especially in the ileocecal region), the food containing M. tuberculosis has become chyme, which has a greater chance of direct contact with the intestinal mucosa, and the existence of physiological retention and retrograde peristalsis in the ileocecal region increases the chance of infection. In addition, there is rich lymphatic tissue in the ileocecal region, which has a strong susceptibility to tuberculosis, therefore, the ileocecal region becomes a good site for intestinal tuberculosis.
Blood-borne transmission
Blood-borne transmission is also one of the infection routes of intestinal tuberculosis. It can be seen in the blood-borne spread of the tuberculosis pathway and invade the intestine.
Third, the spread of adjacent TB foci
Intestinal tuberculosis can also be caused by the direct spread of intra-abdominal tuberculosis lesions, such as tuberculosis of fallopian tubes, tuberculous peritonitis, mesenteric lymphatic tuberculosis. This infection is spread through the lymphatic vessels.
Tuberculosis, like many other diseases, is the result of the interaction between the body and bacteria (or other pathogenic factors). The disease is caused only when the number of invading Mycobacterium tuberculosis is high and virulent and when the immune function of the body is abnormal (including the weakening of local resistance due to intestinal dysfunction).
Pathological changes
Tuberculosis of the intestine is usually found in the ileocecal region, followed by the ascending colon, jejunum, transverse colon, descending colon, appendix, duodenum, and sigmoid colon, and occasionally in the rectum. Gastric tuberculosis has also been reported, but it is very rare.
The pathological changes after the invasion of tubercle bacilli into the intestine depend on the immunity and allergic reaction of the body to the tubercle bacilli. When the amount of infected bacteria is high, the virulence is high, and the body’s allergic reaction is strong, the lesions tend to be mainly exudative. If the infection is mild and the body’s immunity (mainly cellular immunity) is strong, the lesion is often proliferative, with granulation tissue proliferation, forming nodules and further fibrosis, called proliferative intestinal tuberculosis. In fact, it is not uncommon to have both ulcerative and hyperplastic lesions, which is called mixed or ulcerative-proliferative intestinal tuberculosis.
I. Ulcerative intestinal tuberculosis
After the invasion of Mycobacterium tuberculosis into the intestinal wall, firstly, there are lesions such as congestion, edema and exudation in the lymphatic tissues of the intestinal wall, and then caseous necrosis occurs, followed by the formation of ulcers and their expansion to the surrounding area, and the edges of the ulcers can be irregular and of different depths, sometimes reaching the muscle layer or plasma layer, or even involving the surrounding peritoneum or adjacent mesenteric lymph nodes. Ulcerated intestinal tuberculosis often adheres to extraintestinal tissues, so the incidence of intestinal perforation is low. The ulcers of intestinal tuberculosis may expand with the lymphatic vessels of the intestinal wall, mostly in the form of rings. During the repair process, there is a large amount of fibrous tissue proliferation and scar formation, which can easily lead to circular narrowing of the intestinal lumen. In addition, there is occlusive endocarditis in the blood vessels of the ulcerated area, so ulcerated intestinal tuberculosis rarely causes hemorrhage.
Proliferative intestinal tuberculosis
It is commonly found in the cecum and ascending colon. In the initial stage, there is local edema and dilated lymphatic vessels. In the chronic stage, there is a large amount of tuberculous granulation tissue and fibrous tissue hyperplasia, mainly in the submucosa, in the form of nodules of different sizes, or in severe cases, in the form of tumor-like masses protruding into the intestinal lumen and forming intestinal stenosis, or even intestinal obstruction. The diseased intestinal segment is narrowed and thickened, or adheres to the surrounding tissues and forms a mass. The ileum is often enlarged due to chronic obstruction of the cecum.
Clinical manifestations
Most patients with intestinal tuberculosis have a slow onset and long course, and most of them lack specific clinical manifestations.
I. Abdominal pain
Because the lesion often involves the ileocecal region, pain is most commonly found in the right lower abdomen, and limited pressure points can be found upon palpation. The pain can also be located around the umbilicus, which is caused by the traction of the lesion in the ileocecal region. The pain is usually mild, vague or dull, or intermittent, often induced during or after meals, which is caused by the gastro-ileal reflex or gastrocolic reflex caused by eating; the postprandial pain is caused by the spasm or peristaltic enhancement of the intestinal flexure of the lesion, so the pain is often accompanied by bowel movement, and the pain can be relieved after defecation. When proliferative intestinal tuberculosis is complicated by intestinal obstruction, the abdominal pain is mainly colic, and there are corresponding symptoms of intestinal obstruction.
Diarrhea and constipation
Diarrhea is one of the main symptoms of ulcerative intestinal tuberculosis, which is caused by inflammation and ulcer stimulation of intestinal curvature, accelerated intestinal peristalsis, rapid evacuation and secondary malabsorption. The bowel movements are usually 2 to 4 times a day, mostly pasty stools, containing only a small amount of mucus in mild cases, but in severe cases the diarrhea can be up to 10 times a day, with mucus and pus in the stool, and blood in the stool is less common. In addition, there can be constipation, stools in the shape of sheep feces, or diarrhea and constipation alternately.
Abdominal masses
It is mainly seen in hyperplastic intestinal tuberculosis, where the intestinal wall is thickened locally to form a mass. When ulcerative intestinal tuberculosis and surrounding tissues are adherent, or when mesenteric lymphatic tuberculosis is also present, a mass can be formed and can be felt. The mass is usually located in the right lower abdomen, moderately hard, with light pressure pain, sometimes with uneven surface and little movement.
Systemic symptoms
Ulcerative intestinal tuberculosis often has tuberculosis toxemia, such as afternoon hypothermia, irregular fever, flaccid fever or retention fever, accompanied by night sweats, and may have signs and symptoms such as weakness, emaciation, anemic dystrophic edema, and may have extra-intestinal tuberculosis, especially tuberculous peritonitis, pulmonary tuberculosis and other related manifestations, while proliferative intestinal tuberculosis mostly does not have tuberculosis toxicity symptoms, has a longer disease duration, and has a better general condition.
Clinical diagnosis
The diagnosis of typical cases is generally not difficult. However, in the early stage of the disease, the diagnosis is often missed due to the lack of obvious symptoms or characteristic features. The following points can be used as the basis for the diagnosis of the disease.
I. Young and strong patients with clinical manifestations of prolonged fever, night sweats, abdominal pain, diarrhea (or constipation).
Second, patients with pulmonary tuberculosis or other extra-intestinal tuberculosis whose original lesions have improved, but whose gastrointestinal symptoms and tuberculosis toxemia symptoms have worsened.
Third, right lower abdominal mass with pressure pain, or incomplete intestinal obstruction of unknown origin.
IV. Those who have signs of irritation, barium filling defect or stenosis in the ileocecal region on gastrointestinal X-ray.
Laboratory and other tests
I. Blood picture and sedimentation
Total white blood cells are generally normal, lymphocytes are often high, red blood cells and hemoglobin are often low, and there is mild to moderate anemia, which is more common in patients with ulcerative type. In patients with active lesions, blood sedimentation is often increased.
Stool examination
The fecal examination of hyperplastic intestinal tuberculosis has no obvious changes. Fecal microscopy of ulcerative intestinal tuberculosis shows a small number of pus cells and red blood cells. The fecal concentration to find TB bacilli is only meaningful when sputum is negative.
X-ray examination
X-ray barium meal imaging or barium enema examination is important for the diagnosis of intestinal tuberculosis. Patients with concomitant intestinal obstruction should only have barium enema to avoid aggravating the obstruction by barium meal examination. The ulcerative intestinal tuberculosis intestinal segment has more irritation phenomenon, barium empties quickly and fills poorly, and the upper and lower intestinal segments of the lesion fill well with barium, which is called the jump sign. This is called the jump sign. Signs such as hyperplastic intestinal tuberculosis. When there is intestinal obstruction, the proximal bowel curve is often significantly dilated.
Four, fiber colonoscopy
Direct observation of the whole colon, cecum and ileocecal lesions is possible, and biopsy or sampling for bacterial culture is also feasible.