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I have read with considerable interest the paper by N Yukawa et al concerning intra-alveolar haemorrhage in infant deaths,1 and Professor Berry's editorial response. I also applaud the authors' ambition to bring some scientific objectivity to this controversial issue.J Clin Pathol 2000;53:484
The results of their investigation are extremely difficult to interpret, however, because the authors have carried out morphometric analysis of the area of the alveolar space occupied by blood when biased by some prior knowledge of the diagnostic category of each case. The authors concede their impression that pulmonary haemorrhage is a marker of asphyxia. Armed with this preconception and the knowledge of the initial diagnosis made in a case, there is an unavoidable tendency to “select” for analysis from a microscopic field a “random” alveolus that supports the observer's opinion. Indeed, each case was placed in an initial diagnostic category based no doubt to some extent on the subjective degree of pulmonary haemorrhage. Furthermore, we are not told how many alveoli were analysed from each case, nor whether lung tissue was sampled randomly at postmortem examination.
Their data in this paper would have been more robust if each case had been assigned a diagnostic category based on criteria excluding the histology, only after blinded morphometric analysis of lung tissue. Resolution of the hypothesis that lung haemorrhage in a baby is a marker of upper airway obstruction awaits such rigorous scrutiny.
The authors reply
We are pleased that Dr Batman has read our recent paper with interest. We emphasise that the subjective assessment of haemorrhage was carried out blind after the quantitative studies had taken place, and these results were therefore not biased by prior knowledge of the degree of haemorrhage in the individual cases. We dispute Dr Batman's assertion that there was an unavoidable tendency to select alveoli for quantitative analysis: random selection at 4 mm intervals as detailed in the paper meant precisely that—random.
We readily accept that the treatment of this difficult subject was not ideal, but at the very least, our study intended to try and introduce some objectivity into what is always a problem diagnosis. Given that we strongly suspect that intra-alveolar haemorrhage is a marker of asphyxia, we are pleased to draw Dr Batman's attention to a recent study from France,1 which concludes that intra-alvrolar haemosiderin, the end product of haemorrhage, is a marker for chronic child abuse.