Tuberculosis of the Alimentary Tract
Despite the overall prevalence of tuberculosis in many parts of the tropics, there is no part of the world where tuberculosis commonly affects the gastrointestinal system. In the past, before drug therapy became available and patients died of advanced tub
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Tuberculosis of the Alimentary Tract
Despite the overall prevalence of tuberculosis in many parts of the tropics, there is no part of the world where tuberculosis commonly affects the gastrointestinal system. In the past, before drug therapy became available and patients died of advanced tuberculosis, about 80% were found to have abdominal tuberculosis at autopsy; the more advanced the pulmonary tuberculosis, the more likely there was to be bowel infection. However, now that treatment has become possible, the correlation of pulmonary tuberculosis with abdominal tuberculosis has altered, and less than 50% (in some series 25%) of patients with abdominal tuberculosis have pulmonary tuberculosis also. This ratio may again alter significantly with AIDS; for example, already in Haiti patients with AIDS are 3.5 times more likely to have extrapulmonary tuberculosis than patients who are HIV-negative. Tuberculosis in the bowel starts as a localized inflammation of the lymphoid tissue and progresses to necrosis. The reaction can be ulcerating or hypertrophic or both. Tuberculous ulcers in the bowel are often transverse and linear, rather than round. Throughout the alimentary tract, tuberculosis forms granulomas which may be demonstrated as a mass, as distortion due to fibrosis, or as a stricture. When the infection has healed, there may be a residual scar, adhesions, or an ulcer on the damaged tissue. Except in tuberculous peritonitis (p. 67) there are no clinical or laboratory criteria which are of any significance other than the histology. Stool culture for tuberculosis is unreliable. The symptomatology is vague and cannot be related satisfactorily to the abdominal lesions in the majority of patients. III health, vomiting, diarrhea (30%), and constipation (20%) are all generalized symptoms. Malabsorption is not uncommon. Analysis of the blood is normal except for anemia, which is very common in tropical countries and is more likely to indicate the presence of parasites rather than tuberculous bowel. There is no close relationship between pulmonary and alimentary tuberculosis. Many patients will have active lung disease, but a normal chest x-ray does not exclude tuberculosis in the alimentary tract. P. E. S. Palmer, The Imaging of Tuberculosis © Springer-Verlag Berlin Heidelberg 2002
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The development of imaging by scanning (ultrasonography, CT, or MRI) has provided a better understanding of the pathophysiology and clinical pattern of tuberculosis in the abdomen. The diagnostic index of suspicion for tuberculosis has been raised, but unfortunately this is all that imaging can do; there are no specific changes for any form of intraabdominal tuberculosis. Nevertheless, all current methods of imaging provide very useful guidance and are invaluable in follow-up during or after treatment. The two most common alimentary forms are peritoneal and cecal tuberculosis; other sites are less frequently affected. But again, it is probable that the incidence and pattern will change in AIDS patients, particularly late in their disease,
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