Unfortunately, differential diagnosis is not a clear-cut science in which physicians are completely confident in what findings or diseases a patient has, and the language used in patient reports expresses the dictating physician's uncertainty on a continuum ranging from certain absence to certain presence. Consider the implications of sentences (5) to (12). The first sentence expresses certainty that pneumonia is absent, whereas the last sentence expresses certainty that pneumonia is present. The intervening sentences express different amounts of uncertainty about a diagnosis of pneumonia. A sophisticated expert system may try to incorporate uncertainty of the variables into its decision making. A simpler expert system may only allow variables to be present or absent. In that case, determining whether pneumonia is negated in the sentences below depends on the goal of the expert system. An expert system designed to be especially sensitive may accept a finding with uncertainty to be present and may set the value of pneumonia to yes for all but the first two sentences. An expert system designed to be specific may consider uncertainty about the variable an indication of negation and may only set the value of pneumonia to yes for the last two.
(5) The chest x-ray ruled out pneumonia.
(6) We performed a chest x-ray to rule out pneumonia.
(7) Cannot rule out pneumonia.
(8) It is not clear whether the opacity is atelectasis or pneumonia.
(9) Radiographic findings may be consistent with pneumonia.
(10) Discharge diagnosis: possible pneumonia.
(11) The patient has pneumonia.
(12) He did have sputum that grew out klebsiella pneumonia during his admission.
Was this article helpful?