Differential Diagnosis in Pediatrics: A Probabilistic Approach.

How physicians arrive at a diagnosis has been the subject of much debate. Pattern recognition is used extensively by experts and is the most common method used by pediatricians. Many of the diagnostic questions posed in certification and self-study examinations developed by the American Board of Pediatrics and the American Academy of Pediatrics require the test taker to recognize a pattern of symptoms and laboratory tests and draw a conclusion about the most likely diagnosis. This method of diagnosis involves paralleling familiar situations independent of explicit hypothesis testing.1 Sackett et al describe this process as “the instantaneous realization that the patient’s presentation conforms to a previously learned picture or pattern of disease.”2Pattern recognition has several shortcomings. First, the method is highly dependent on the clinician’s experience; novices are at a distinct disadvantage. Second, lists may vary from specialty to specialty. A pediatric infectious disease specialist may have a different list for acute childhood arthritis from that of a pediatric rheumatologist. Finally, the method fails when confronted with a defined clinical problem lacking distinguishing features, such as neonatal …