Normal chest radiography in pulmonary tuberculosis: implications for obtaining respiratory specimen cultures.

SETTING: Urban tuberculosis (TB) clinic, Nashville, Tennessee, USA. OBJECTIVE: Chest radiographs (CXRs) help in the diagnosis of pulmonary TB, but may be normal. Mycobacterium tuberculosis in culture is diagnostic of TB, but cultures are not routinely obtained in resource-poor settings. We examined rates and risk factors for pulmonary TB associated with normal CXR. DESIGN: An observational cohort study was performed among all respiratory culture-positive TB cases referred to the Nashville Health Department from October 1992 to July 2003. Clinical factors, demographics and underlying medical conditions were assessed. RESULTS: Of 601 study patients, 53 (9%) had normal CXRs: 31/138 (22%) were human immunodeficiency virus (HIV) infected and 22/463 (5%) were non-HIV-infected/unknown (P<0.001). Among HIV-infected patients, normal CXR was more likely in persons with renal failure (13% vs. 3%, P=0.048). Among non-HIV-infected/unknown patients, normal CXR was more likely in those who were asymptomatic at presentation (32% vs. 13%, P=0.022). In multivariable logistic regression analysis, HIV infection was associated with an increased risk of normal CXR (odds ratio [OR] 6.61, P<0.0001); factors associated with reduced risk were dyspnea (OR 0.24, P=0.026), positive sputum smear (OR 0.45, P=0.028) and cough (OR 0.48, P=0.038). CONCLUSIONS: The rate of normal CXR among persons with culture-confirmed pulmonary TB was high. Respiratory specimen cultures should be obtained in TB suspects with a normal CXR, particularly HIV-infected persons.

Accuracy of assessment of the extent of examination by experienced colonoscopists.

One hundred colonoscopies were done. The colonoscopist noted whether the cecum had been intubated as well as the markers used to make this determination. With the colonoscope in position at maximum penetration, a radiologist independently determined its position using fluoroscopy, with a contrast agent delivered through the colonoscope. The cecum was entered in 86 of 100 cases. The tip of the colonoscope was at the level of the ileocecal valve in nine additional cases; the colonoscopist judged that the cecum was well seen in five of these nine. In one case, the colonoscopist overestimated the extent of the examination when transillumination in the right lower quadrant was the only confirming marker. When the more reliable markers (ileocecal valve, appendiceal orifice, converging indentations of the taenia coli in the cecal pole) were seen, no errors were made. Experienced colonoscopists are accurate in assessing the extent of colonoscopy and fluoroscopic confirmation is not routinely needed. When reliable markers are not seen during the examination, a barium enema, preferably with air contrast, should be done.