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Perinatal necropsy by magnetic resonance imaging
THE LANCET
CORRESPONDENCE
Perinatal necropsy by magnetic resonance imaging SIR—Brookes and colleagues (Oct 26, p 1139)1 conclude that MRI scanning of stillborn and aborted fetuses “may provide a useful, non-invasive and acceptable alternative to internal necropsy when consent for necropsy is denied”. This carefully phrased claim should not be taken to mean that MRI is an alternative to conventional perinatal necropsy. Indeed, much the same was said for ultrasound scanning with little impact on practice.2 They concede that their sample of 20 was biased towards fetuses with structural abnormalities, and therefore towards those in whom MRI scanning was likely to succeed. Even in these cases the identification of anatomical abnormalities is unlikely to provide a complete diagnosis for genetic counselling because similar structural abnormalities can have very different causes, and the same genetic syndrome could have very different structural manifestations. Postmortem examination adds greatly to genetic counselling, not only by reassigning mistaken interpretations, but also by providing additional findings inaccessible to imaging.3 Postmortem examination is an opportunity to save samples for cytogenetic and DNA analysis. Most stillborn and aborted fetuses do not have structural abnormalities: the mode of death is inferred from other pathological findings. In around 40% of stillbirths the placenta provides essential evidence of uteroplacental vascular insufficiency, amnionitis, or placental abruption. Although there is not always a single cause of death perinatal pathologists provide useful information about the time of intrauterine death, growth, and development needed for planning future pregnancies. Only conventional necropsy can provide absolute assurance that there was no malformation. Were the radiologists and pathologist blinded to each others findings when they made the initial interpretations, and whose view was taken as correct? For example, who decided that the bilateral intraventricular haemorrhage “seen” by MRI was missed by the pathologist, rather than imagined
Vol 349 • January 4, 1997
by the radiologist? A study of postmortem cranial MRI and necropsy in suspected child abuse showed that necropsy is better than MRI in the detection of subarachnoid and subdural haemorrhage,4 and others have shown that not all MRI findings have clear clinical and pathological correlates. Most pathologists conceded that they might miss minor ventriculomegaly in an autolysed fetal brain and defer to antenatal ultrasound, but not that they would miss intraventricular haemorrhage. Brookes et al give the national; necropsy rate as 45%. In fact rates of over 90% are achieved in many units in the UK. Consent to the postmortem examination of neonates (not included in this study) can be difficult. It is essential that we respond sensitively to changing public and parental perceptions of death. However, the commonest reasons for lack of consent are that the parents were not asked, or that explanation of the benefits of the examination was left to an inexperienced junior doctor who did not understand its importance. Perinatal necropsy is a parental right, which may be essential to the future wellbeing of that family. Parents and their doctors should be clear that a complete examination includes full necropsy and that necropsy is the gold standard.5 Brookes has shown that MRI scanning may enhance the contribution of imaging to postmortem examination (subject to cost and availability), but not that it will replace necropsy. We welcome the precedent they have set, and will now consider MRI in the few cases with structural anomalies in whom postmortem consent is refused. *P J Berry, J W Keeling, J S Wigglesworth *Department of Paediatric Pathology, School of Medical Sciences, Bristol University, Bristol BS8 1TD, UK; Royal Hospital for Sick Children, Edinburgh; and the Royal Postgraduate Medical School, London
1
2
Brookes JAS, Hall-Craggs MA, Sams VR, Lees WR. Non-invasive perinatal necropsy by magnetic resonance imaging. Lancet 1996; 348: 1139–41. Furness ME, Weckert RC, Parker SA,
3
4
5
Knowles S. Ultrasound in the perinatal necropsy. J Med Genet 1989; 26: 368–72. Weston MJ, Porter HJ, Andrews HS, Berry PJ. Correlation of antenatal ultrasonography and pathological examinations in 153 malformed fetuses. J Clin Ultrasound 1993; 21: 387–92. Hart, Dudley MH, Zumwalt RE. Postmortem cranial MRI and autopsy correlation in suspected child abuse. Am J Forens Med Pathol 1996; 17: 217–14. Porter HJ, Keeling JW. Value of perinatal necropsy examination. J Clin Pathol 1987; 40: 180–84.
Authors’ reply SIR—We agree with much of what Berry and colleagues say, and for this reason we made very limited claims for the technique. We did not suggest that MRI in isolation is an alternative to conventional perinatal necropsy when consent for this procedure is given. Clearly, we do not dispute that full perinatal necropsy is the gold standard of postmortem diagnosis. Unfortunately, despite regular published reminders from Berry and colleagues and from the Royal Colleges of Pathologists and Obstetricians and Gynaecologists promoting the necropsy service, nearly half the affected population fail to give consent for several reasons including, as Berry and colleagues state, the parents not being asked, or a junior doctor who does not understand the importance of necropsy being left to ask for parental permission. Cartlidge1 reported that 17% of parents were not asked for and 25% refused consent. Most people have no objection to the non-invasive procedures associated with postmortem examination. It is the internal dissection for gross morphological abnormalities and the extraction of material for histological examination with consequent multilation of the body that offends the sensibilities of many parents. It is against this invasive procedure alone that we assessed the MRI findings in our study. MRI alone did almost as well as necropsy in demonstrating the presence and absence of morphological abnormalities, as we explained, but was more sensitive than necropsy for showing structural anomalies of the skeleton and fluid-space anomalies.
55
THE LANCET
The absence of histological material with imaging alone is an obvious drawback, which we clearly state. However, image-guided (including MRI and ultrasound) biopsy techniques are available, and needle cores and aspirates can be obtained from areas of interest with minimum physical disturbance to the baby. Even without these, the close correlation found in our study between MRI and internal necropsy argues in favour of the use of MRI if parental consent for full necropsy is not forthcoming: it does not conflict with the pursuit of a higher conventional necropsy rate. Moreover, for nearly half the affected population it may provide at least some of the information that would otherwise not be available. When no consent is given no information can be derived, and in such instances MRI, yielding some of this information, is a reasonable proxime acessit in the context of other supportive non-invasive investigations. With the enthusiastic co-operation of radiologists and pathologists achieved at our centre, it may become possible to derive maximum information, not from a self-selected sample (ie, those who consent to full necropsy), but from most of the affected population and in a manner acceptable to all patients. *Jocelyn A S Brookes, Margaret A Hall-Craggs, Virginia R Sams, William R Lees Departments of *Medical Imaging and Histopathology, Middlesex Hospital, London W1N 8AA, UK
1
Cartlidge PH, Dawson AT, Stewart JH, Vujanic GM. Value and quality of perinatal and infant postmortem examinations: cohort analyses of 400 consecutive deaths. BMJ 1995; 310: 155–58.
SIR—Among the dictionary definitions of an image are “an artificial imitation or representation, a semblance”. The report by Brookes and colleagues1 raises fundamental issues about our attitudes to reality and representations of reality. If imaging techniques are used to demonstrate anatomy and pathology the only certain method of validation is to compare the image with the original specimen. If the original is examined by an appropriately trained and skilled practitioner any differences between the image and reality cannot be explained by dismissing reality. Even with the best of modern imaging techniques there remain differences in resolution between the original and the image, which are amply illustrated by the two images in figure 1 of Brookes’ report. If, as reported, bilateral intraventricular haemorrhages, haemothorax, and pericardial and pleural effusions were identified on scan and not at necropsy there can be only three explanations. First, the
56
standard of necropsy was below that expected in a centre with a perinatal pathologist, which seems unlikely. Second, major pathological lesions may disappear after death. If so, there would have to be a complete reappraisal of necropsy technique. Third, the scan provides inaccurate information or that information is being misinterpreted. There can be little disagreement as to whether a haemorrhage or effusion is present at necropsy. However, those of us familiar with medicolegal cases are frequent witnesses to two or more experts providing different interpretations of the same scans. Sometimes specific diagnoses are made on scans, but are not shown at necropsy, done with knowledge of the diagnosis. In the absence of observer error the final arbiter as to the validity of the scan results must remain examination of the original specimen. If the gold standard for accuracy becomes the image then the consequences could be catastrophic, especially in medical litigation and forensic medicine. How do we know that Brookes’ examples in which discrepancies have been identified are correct? In those cases in which necropsy identified lesions not seen on scan, reality prevailed; so why—in the reverse situation—is reality apparently rejected unless it is implied that the necropsy examinations were inadequate, a conclusion not clearly drawn in the text? If the examinations were inadequate then clearly this report is a warning to pathologists; the report does not indicate that MRI scans are better than a properly performed necropsy. The implied separation of the histological examination from the macroscopic examination is misleading. The microscopic examination should be an essential component of a complete perinatal necropsy, and can only be done after appropriate tissue samples have been obtained. At a time when we are trying to raise standards we must not be seduced into believing that representations of reality are equal to or even better than reality itself. Imaging, like microbiology or cytogenetics, is an aid to necropsy: it is not a substitute. D I Rushton Perinatal Pathology, University of Birmingham, Birmingham Maternity Hospital, Birmingham B15 2TG, UK
1
Brookes JAS, Hall-Craggs MA, Sams VR, Lees WR. Non-invasive perinatal necropsy by magnetic resonance imaging. Lancet 1996; 348: 1139–41.
SIR—Brookes and colleagues1 suggest postmortem MRI as a potentially informative and possibly more acceptable alternative to a full necropsy, after an intrauterine or neonatal death. Their arguments seem practical and
plausible, but for any relevant fetal/neonatal pathology work-up one needs a full description and photographs of the child and its dysmorphisms, supplemented by a full necropsy, tissue samples obtained for microscopy, cytogenetics, DNA, and metabolic studies, as become appropriate during the analysis. The painfulness of stillbirth or neonatal death—especially if many perinatal or neonatal diagnostic studies or imagings have been done—often induces the considerate pediatrician not to emphasise the importance of a full necropsy to the bereaved parents. However, many clinical genetic departments (and the referred parents) are confronted later on with the absence of data that might have been obtained without undue infringement of the dignity of the child and its parents. MRI may assist the human eye, but can never replace a paediatric pathologist’s necropsy and other diagnostic studies, in achieving the options for parents to understand the reason for the loss of their child, and risk of recurrence. M F Niermeijer Department of Clinical Genetics, Erasmus University and University Hospital Dijkzigt, 3016AH Rotterdam, Netherlands
1
Brookes JAS, Hall-Craggs MA, Sams VR, Lees WR. Non-invasive perinatal necropsy by magnetic resonance imaging. Lancet 1996; 348: 1139–41.
Co-sleeping and sudden infant death syndrome SIR—I am concerned that Mitchell (Nov 30, p 1466)1 seems to have accepted that there is a relation between co-sleeping and the sudden infant death syndrome (SIDS), and that the reasons for and mechanisms of this relationship are under scrutiny without addressing the most fundamental difficulty in these cases: how can and do we distinguish between overlaying, suffocation, and SIDS? Since the diagnosis of SIDS is essentially a diagnosis by exclusion and it is impossible to exclude overlaying and suffocation with absolute certainty, the decision about which diagnosis to accept must be made on a balance of probabilities. This decision is sometimes taken by an individual (usually a pathologist) and sometimes by a committee of experts, including paediatricians, pathologists, and other medical and paramedical workers familiar with the family background often after a case conference. This balance is frequently influenced in favour of the diagnosis of SIDS by the natural desire to give the bereaved
Vol 349 • January 4, 1997
CORRESPONDENCE
Perinatal necropsy by magnetic resonance imaging SIR—Brookes and colleagues (Oct 26, p 1139)1 conclude that MRI scanning of stillborn and aborted fetuses “may provide a useful, non-invasive and acceptable alternative to internal necropsy when consent for necropsy is denied”. This carefully phrased claim should not be taken to mean that MRI is an alternative to conventional perinatal necropsy. Indeed, much the same was said for ultrasound scanning with little impact on practice.2 They concede that their sample of 20 was biased towards fetuses with structural abnormalities, and therefore towards those in whom MRI scanning was likely to succeed. Even in these cases the identification of anatomical abnormalities is unlikely to provide a complete diagnosis for genetic counselling because similar structural abnormalities can have very different causes, and the same genetic syndrome could have very different structural manifestations. Postmortem examination adds greatly to genetic counselling, not only by reassigning mistaken interpretations, but also by providing additional findings inaccessible to imaging.3 Postmortem examination is an opportunity to save samples for cytogenetic and DNA analysis. Most stillborn and aborted fetuses do not have structural abnormalities: the mode of death is inferred from other pathological findings. In around 40% of stillbirths the placenta provides essential evidence of uteroplacental vascular insufficiency, amnionitis, or placental abruption. Although there is not always a single cause of death perinatal pathologists provide useful information about the time of intrauterine death, growth, and development needed for planning future pregnancies. Only conventional necropsy can provide absolute assurance that there was no malformation. Were the radiologists and pathologist blinded to each others findings when they made the initial interpretations, and whose view was taken as correct? For example, who decided that the bilateral intraventricular haemorrhage “seen” by MRI was missed by the pathologist, rather than imagined
Vol 349 • January 4, 1997
by the radiologist? A study of postmortem cranial MRI and necropsy in suspected child abuse showed that necropsy is better than MRI in the detection of subarachnoid and subdural haemorrhage,4 and others have shown that not all MRI findings have clear clinical and pathological correlates. Most pathologists conceded that they might miss minor ventriculomegaly in an autolysed fetal brain and defer to antenatal ultrasound, but not that they would miss intraventricular haemorrhage. Brookes et al give the national; necropsy rate as 45%. In fact rates of over 90% are achieved in many units in the UK. Consent to the postmortem examination of neonates (not included in this study) can be difficult. It is essential that we respond sensitively to changing public and parental perceptions of death. However, the commonest reasons for lack of consent are that the parents were not asked, or that explanation of the benefits of the examination was left to an inexperienced junior doctor who did not understand its importance. Perinatal necropsy is a parental right, which may be essential to the future wellbeing of that family. Parents and their doctors should be clear that a complete examination includes full necropsy and that necropsy is the gold standard.5 Brookes has shown that MRI scanning may enhance the contribution of imaging to postmortem examination (subject to cost and availability), but not that it will replace necropsy. We welcome the precedent they have set, and will now consider MRI in the few cases with structural anomalies in whom postmortem consent is refused. *P J Berry, J W Keeling, J S Wigglesworth *Department of Paediatric Pathology, School of Medical Sciences, Bristol University, Bristol BS8 1TD, UK; Royal Hospital for Sick Children, Edinburgh; and the Royal Postgraduate Medical School, London
1
2
Brookes JAS, Hall-Craggs MA, Sams VR, Lees WR. Non-invasive perinatal necropsy by magnetic resonance imaging. Lancet 1996; 348: 1139–41. Furness ME, Weckert RC, Parker SA,
3
4
5
Knowles S. Ultrasound in the perinatal necropsy. J Med Genet 1989; 26: 368–72. Weston MJ, Porter HJ, Andrews HS, Berry PJ. Correlation of antenatal ultrasonography and pathological examinations in 153 malformed fetuses. J Clin Ultrasound 1993; 21: 387–92. Hart, Dudley MH, Zumwalt RE. Postmortem cranial MRI and autopsy correlation in suspected child abuse. Am J Forens Med Pathol 1996; 17: 217–14. Porter HJ, Keeling JW. Value of perinatal necropsy examination. J Clin Pathol 1987; 40: 180–84.
Authors’ reply SIR—We agree with much of what Berry and colleagues say, and for this reason we made very limited claims for the technique. We did not suggest that MRI in isolation is an alternative to conventional perinatal necropsy when consent for this procedure is given. Clearly, we do not dispute that full perinatal necropsy is the gold standard of postmortem diagnosis. Unfortunately, despite regular published reminders from Berry and colleagues and from the Royal Colleges of Pathologists and Obstetricians and Gynaecologists promoting the necropsy service, nearly half the affected population fail to give consent for several reasons including, as Berry and colleagues state, the parents not being asked, or a junior doctor who does not understand the importance of necropsy being left to ask for parental permission. Cartlidge1 reported that 17% of parents were not asked for and 25% refused consent. Most people have no objection to the non-invasive procedures associated with postmortem examination. It is the internal dissection for gross morphological abnormalities and the extraction of material for histological examination with consequent multilation of the body that offends the sensibilities of many parents. It is against this invasive procedure alone that we assessed the MRI findings in our study. MRI alone did almost as well as necropsy in demonstrating the presence and absence of morphological abnormalities, as we explained, but was more sensitive than necropsy for showing structural anomalies of the skeleton and fluid-space anomalies.
55
THE LANCET
The absence of histological material with imaging alone is an obvious drawback, which we clearly state. However, image-guided (including MRI and ultrasound) biopsy techniques are available, and needle cores and aspirates can be obtained from areas of interest with minimum physical disturbance to the baby. Even without these, the close correlation found in our study between MRI and internal necropsy argues in favour of the use of MRI if parental consent for full necropsy is not forthcoming: it does not conflict with the pursuit of a higher conventional necropsy rate. Moreover, for nearly half the affected population it may provide at least some of the information that would otherwise not be available. When no consent is given no information can be derived, and in such instances MRI, yielding some of this information, is a reasonable proxime acessit in the context of other supportive non-invasive investigations. With the enthusiastic co-operation of radiologists and pathologists achieved at our centre, it may become possible to derive maximum information, not from a self-selected sample (ie, those who consent to full necropsy), but from most of the affected population and in a manner acceptable to all patients. *Jocelyn A S Brookes, Margaret A Hall-Craggs, Virginia R Sams, William R Lees Departments of *Medical Imaging and Histopathology, Middlesex Hospital, London W1N 8AA, UK
1
Cartlidge PH, Dawson AT, Stewart JH, Vujanic GM. Value and quality of perinatal and infant postmortem examinations: cohort analyses of 400 consecutive deaths. BMJ 1995; 310: 155–58.
SIR—Among the dictionary definitions of an image are “an artificial imitation or representation, a semblance”. The report by Brookes and colleagues1 raises fundamental issues about our attitudes to reality and representations of reality. If imaging techniques are used to demonstrate anatomy and pathology the only certain method of validation is to compare the image with the original specimen. If the original is examined by an appropriately trained and skilled practitioner any differences between the image and reality cannot be explained by dismissing reality. Even with the best of modern imaging techniques there remain differences in resolution between the original and the image, which are amply illustrated by the two images in figure 1 of Brookes’ report. If, as reported, bilateral intraventricular haemorrhages, haemothorax, and pericardial and pleural effusions were identified on scan and not at necropsy there can be only three explanations. First, the
56
standard of necropsy was below that expected in a centre with a perinatal pathologist, which seems unlikely. Second, major pathological lesions may disappear after death. If so, there would have to be a complete reappraisal of necropsy technique. Third, the scan provides inaccurate information or that information is being misinterpreted. There can be little disagreement as to whether a haemorrhage or effusion is present at necropsy. However, those of us familiar with medicolegal cases are frequent witnesses to two or more experts providing different interpretations of the same scans. Sometimes specific diagnoses are made on scans, but are not shown at necropsy, done with knowledge of the diagnosis. In the absence of observer error the final arbiter as to the validity of the scan results must remain examination of the original specimen. If the gold standard for accuracy becomes the image then the consequences could be catastrophic, especially in medical litigation and forensic medicine. How do we know that Brookes’ examples in which discrepancies have been identified are correct? In those cases in which necropsy identified lesions not seen on scan, reality prevailed; so why—in the reverse situation—is reality apparently rejected unless it is implied that the necropsy examinations were inadequate, a conclusion not clearly drawn in the text? If the examinations were inadequate then clearly this report is a warning to pathologists; the report does not indicate that MRI scans are better than a properly performed necropsy. The implied separation of the histological examination from the macroscopic examination is misleading. The microscopic examination should be an essential component of a complete perinatal necropsy, and can only be done after appropriate tissue samples have been obtained. At a time when we are trying to raise standards we must not be seduced into believing that representations of reality are equal to or even better than reality itself. Imaging, like microbiology or cytogenetics, is an aid to necropsy: it is not a substitute. D I Rushton Perinatal Pathology, University of Birmingham, Birmingham Maternity Hospital, Birmingham B15 2TG, UK
1
Brookes JAS, Hall-Craggs MA, Sams VR, Lees WR. Non-invasive perinatal necropsy by magnetic resonance imaging. Lancet 1996; 348: 1139–41.
SIR—Brookes and colleagues1 suggest postmortem MRI as a potentially informative and possibly more acceptable alternative to a full necropsy, after an intrauterine or neonatal death. Their arguments seem practical and
plausible, but for any relevant fetal/neonatal pathology work-up one needs a full description and photographs of the child and its dysmorphisms, supplemented by a full necropsy, tissue samples obtained for microscopy, cytogenetics, DNA, and metabolic studies, as become appropriate during the analysis. The painfulness of stillbirth or neonatal death—especially if many perinatal or neonatal diagnostic studies or imagings have been done—often induces the considerate pediatrician not to emphasise the importance of a full necropsy to the bereaved parents. However, many clinical genetic departments (and the referred parents) are confronted later on with the absence of data that might have been obtained without undue infringement of the dignity of the child and its parents. MRI may assist the human eye, but can never replace a paediatric pathologist’s necropsy and other diagnostic studies, in achieving the options for parents to understand the reason for the loss of their child, and risk of recurrence. M F Niermeijer Department of Clinical Genetics, Erasmus University and University Hospital Dijkzigt, 3016AH Rotterdam, Netherlands
1
Brookes JAS, Hall-Craggs MA, Sams VR, Lees WR. Non-invasive perinatal necropsy by magnetic resonance imaging. Lancet 1996; 348: 1139–41.
Co-sleeping and sudden infant death syndrome SIR—I am concerned that Mitchell (Nov 30, p 1466)1 seems to have accepted that there is a relation between co-sleeping and the sudden infant death syndrome (SIDS), and that the reasons for and mechanisms of this relationship are under scrutiny without addressing the most fundamental difficulty in these cases: how can and do we distinguish between overlaying, suffocation, and SIDS? Since the diagnosis of SIDS is essentially a diagnosis by exclusion and it is impossible to exclude overlaying and suffocation with absolute certainty, the decision about which diagnosis to accept must be made on a balance of probabilities. This decision is sometimes taken by an individual (usually a pathologist) and sometimes by a committee of experts, including paediatricians, pathologists, and other medical and paramedical workers familiar with the family background often after a case conference. This balance is frequently influenced in favour of the diagnosis of SIDS by the natural desire to give the bereaved
Vol 349 • January 4, 1997