Diagnosis of Pneumocystis carinii Pneumonia

We analyzed the diagnosis of Pneumocystis carinii pneumonia by fiberoptic bronchoscopy in a large series of patients with the acquired immunodeficiency syndrome (AIDS). Transbronchial biopsy fragments, as opposed to endobronchial specimens, were found to have high diagnostic value. Their optimal number for diagnosis was determined by a simple statistical principle. It varied from a minimum of two in cases of severe pneumonia to a maximum of four when roentgenographic manifestations were altogether absent. The diagnostic yield of the transbronchial biopsy alone was 97 percent and that of “touch” preparations of the biopsies 88 percent; when both techniques were combined, the accuracy rose to 98 percent. By comparison, bronchial “washings” and “brushings” had a much lower yield, 59 percent and 57 percent, respectively. Because their diagnostic contribution was negligible, we conclude that the latter two procedures represent an unnecessary expense and waste of technical and professional effort.