Pathology

In the event, however, the anatomy of error in this particular field has so many facets and imponderables that those radiologists who have attempted to review their own store of error quickly come to appreciate the almost insuperable difficulties besetting such a study. Marcus J. Smith's attempt at this is in a recent book,' in many ways amateurish, subjective and idiosyncratic; but his book nevertheless contains much that is of value, and its writing demonstrates an admirable courage and tenacity, in that a largely uncharted and submerged area is explored. The various chapter headings define the author's approach, and include errors from complacency, faulty reasoning, lack of knowledge, underreading, poor communication and, finally, a miscellaneous group falling into no particular category and representative more of disagreement than of frank error. Underreading was, in a collection of nearly 400 errors, the major fault, accounting for 48% of the mistakes; poor communication was responsible for a further 15% of errors; whilst complacency and deductive failures made up about 10% of the total. Lack of knowledge was responsible for a mere 3% of errors in interpretation (so much for the omniscience of the. diagnostic radiologist!) . Errors from underreading are considered more deliberately and with rather greater perspicuity than the remainder, and this chapter justifies detailed consideration. Apart from a slight rise in the number of errors made. on Mondays, when pressures on the radiologist are usually heaviest, the time of day, the day of the week or the month of the year has no influence on the incidence of error. Certain lesions tend regularly to be overlooked, and paramount amongst these are rib fractures, metastases to the ribs and lesions of the lung less than 1 em, in diameter. Smaller tumours of the mediastinum are a common source of underreading, and cardiac enlargement also tends to pass unrecognized. Tuberculosis at either lung apex, renal and biliary calculi, foreign bodies of low opacity at any location, but especially in the chest wall, and congenital bony dystrophies are other important causes of error. Smith lists several important psychological, communicative and physical mechanisms which may hamper accurate interpretation, and which may be held responsible for some instances of underreading; amongst these are: alliterative errors, by which a radiologist is lulled into a false sense of security because a film has been reported as "negative" by someone else; a lack of clinical data; a failure to isolate a lesion visually when this is set against a confusing background-an abdominal aneurysm obscured by barium in small bowel loops being quoted as an example; satisfaction of search, in which the radiologist breaks off his perusal of a film because he has found one abnormality and so fails to recognize another; failure. to perceive lesions in the darker areas of the film; optimism and pessimism-pessimism explaining the underreading of mass miniature chest films in which the expectation of finding a lesion is relatively small; reactions to earlier failuressome radiologists responding by an improved performance, others being reduced to inaction or to such uncertainty that a positive opinion may no longer be given; distraction