The impact of bronchoalveolar lavage cell analysis on clinicians' diagnostic reasoning about interstitial lung disease.

To assess the impact of bronchoalveolar lavage (BAL) on clinicians' diagnostic reasoning, we administered serial telephone questionnaires to all pulmonary physicians submitting BAL specimens to our laboratory from nonimmunocompromised patients with diffuse interstitial lung disease. Questionnaires were completed when the lavage specimens were first submitted and again after the results were reported to referring physicians. We recorded the clinicians' ordered list of likeliest diagnoses for the patient, a level of confidence in each diagnosis mentioned, and any proximate plans for further diagnostic tests. Of 78 patients in the study, information from the BAL fluid cell analysis caused clinicians to change their diagnostic thinking in 46 (59 percent). These changes were far more frequently appropriate (52 percent) than not (9 percent), and clinically impressive changes did occur but were infrequent (3 of 78 [4 percent]) in this series. Specifically, BAL permitted the unexpected diagnosis of Pneumocystis carinii in a patient not previously suspected to have acquired immune deficiency syndrome (AIDS) and appropriately encouraged clinicians to avert planned surgical biopsies in two patients subsequently found to have sarcoidosis. These findings suggest that when used to evaluate nonimmunocompromised patients, BAL fluid cell analysis can have an important impact on clinicians' diagnostic reasoning about their patients' interstitial lung diseases.