Sudden infant death syndrome: diagnostic practices and investigative policies, 2004

Using a 2004 population-based survey of all US medical examiner and coroner offices, we examined the characteristics of offices accepting an infant death case and calculated the percentage of offices that had death scene investigation or autopsy policies for the investigation of sudden unexpected infant death (SUID). We also calculated the percentage of offices that used and did not use sudden infant death syndrome (SIDS) as a cause of death, and we compared differences in characteristics among those offices.Of medical examiner and coroner offices, 52% did not report an infant death in 2004. Of the 7957 infant deaths reported, 43% occurred in jurisdictions that experienced 1 or 2 infant deaths. Of the offices that used SIDS as a classification, 34% did not have policies for conducting death scene investigations and autopsies for SUID. At least 5% of offices that reported an infant death did not use SIDS as a cause of death classification. These findings have important implications for understanding recent trends in SIDS and SUID. Supporting the implementation of national standards for investigating and certifying infant deaths could provide guidelines for consistent practices in medical examiner and coroner offices.     

Oronasal blood in sudden infant death.

Oronasal secretions are observed frequently in sudden infant death syndrome (SIDS), but overt blood is uncommonly reported. The literature on oronasal blood in sudden infant death is limited. The goal of this study was to determine the frequency of oronasal blood in sudden infant deaths and to examine possible causative factors. Oronasal blood was described in 28 (7%) of 406 cases of sudden infant death. Oronasal blood could not be attributed to cardiopulmonary resuscitation in 14 cases, including 10 (3%) of 300 cases of SIDS, 2 (14%) of 14 accidental suffocation cases, and 2 (15%) of 13 undetermined cases. Eight of the 10 infants in cases of sudden infant death were bedsharing: 5 with both parents, 2 between both parents. The infant in 1 SIDS case was from a family that had had three referrals to Child Protective Services. Oronasal blood not attributable to cardiopulmonary resuscitation occurs rarely in SIDS when the infant is sleeping supine in a safe environment. Bedsharing may place infants at risk of suffocation from overlaying. Oronasal blood observed before cardiopulmonary resuscitation is given is probably of oronasal skin or mucous membrane origin and may be a sign of accidental or inflicted suffocation. Sanguineous secretions that are mucoid or frothy are likely of remote origin, such as lung alveoli. The use of an otoscope to establish the origin of oronasal blood in cases of sudden infant death is recommended.     

Homicide as a cause of the sudden infant death syndrome

The homicidal asphyxiation of a 10 1/2-month-old male infant and the attempted asphyxiation of his 4-month-old sibling, documented by parental confession, is presented as evidence that murder may sometimes be mistaken as sudden infant death syndrome (SIDS). A review of the literature of the relationship between murder and SIDS deaths reveals the suspicions of some physicians but few published cases; this reflects not only the difficulties of making a determination of murder by suffocation, since no injuries may be present, but also a lack of awareness among physicians who must evaluate infant deaths. It is recommended that murder should be considered in the differential diagnosis of sudden, unexpected death in infants and that the autopsy should include full-body x-rays and at least an initial look at the social history of the child.     

Cause-of-death query in validation of death certification by expert panel; effects on mortality statistics in Finland, 1995

The correctness of selection, coding and registration of underlying cause-of-death is important for the quality of mortality statistics. One measure to improve quality is the query to the certifier for verification of the underlying cause-of-death. In Finland, 3478 death certificates, 7.1% of total 49074 certifications in 1995, were considered questionable by statisticians. The expert panel at Statistics Finland was able to resolve 2813 (80.9%) of them. However, 665 (19.1%) certificates needed to be further queried from the certifier. Of these, 318 (47.8%) were re-assigned to another ICD-9 category or to the applicable three-digit category within the main category of heart and vascular diseases, resulting in changes from a 17.00-fold increase in rheumatic heart diseases (ICD-9 codes 390-398) to a decrease of about one-half (0.45-fold change) in unspecified neoplasms (codes 235-239). However, a statistically significant impact on national mortality statistics was not observed in any of applied ICD categories. Among all questionable death certificates, most prone to query of the certifier, and with a statistical significance of P<0.05, were those with no cause-of-death specified, those stating underlying cause-of-death as non-specified neoplasms (with a observed/expected ratio, O/E, of 1.69), and heart and vascular diseases (1.45), with its subcategories of ischaemic heart diseases (1.33) and other heart diseases (2.92). Death certificate validation, by expert panel consultations and query to the certifiers, and the importance of estimation of the validity of cause-of-death information on death certificates are strongly pointed out in a continuous strive for correct and reliable mortality statistics.     

Nonnatural death masquerading as SIDS (sudden infant death syndrome)

This article relates our experiences with accidental and homicidal deaths in reported sudden infant death syndrome (SIDS) cases. Our intent is to alert personnel in medical and health-related professions as well as death investigators (coroners, law enforcement officials, etc.) that a thorough scene investigation and history need to be obtained when a child's death has been reported, since this may modify the type of autopsy to be performed. It should not be assumed that all children less than 1 year of age who die suddenly die from SIDS.     

Sudden infant death syndrome (SIDS)--standardised investigations and classification: recommendations

Sudden infant death syndrome (SIDS) still accounts for considerable numbers of unexpected infant deaths in many countries. While numerous theories have been advanced to explain these events, it is increasingly clear that this group of infant deaths results from the complex interaction of a variety of heritable and idiosyncratic endogenous factors interacting with exogenous factors. This has been elegantly summarised in the "three hit" or "triple risk" model. Contradictions and lack of consistencies in the literature have arisen from diverse autopsy approaches, variable applications of diagnostic criteria and inconsistent use of definitions. An approach to sudden infant death is outlined with discussion of appropriate tissue sampling, ancillary investigations and the use of controls in research projects. Standardisation of infant death investigations with the application of uniform definitions and protocols will ensure optimal investigation of individual cases and enable international comparisons of trends.     

Comparative analysis of differences by gender in sudden infant death syndrome in Hungary and Japan

We examined the sex ratio in sudden infant death syndrome (SIDS) cases in Hungary, in Tokyo and Japan between 1985 and 1996. From all the infant death cases in Hungary 395 (240 male, 155 female) were SIDS (odds ratio (OR)=1.179, with 95% confidence interval (CI)=0.961, 1.446), in Japan 4348 (2550 male, 1798 female) were SIDS (OR=1.145, with 95% CI=1.076, 1.218) and in Tokyo 307 (178 male, 129 female) were SIDS (OR=1.128, with 95% CI=0.894, 1.423). Male infants showed a significantly higher birth rate than females. The male infants are more vulnerable (p<0.005), however, higher mortality among male infants should not be considered a characteristic feature for SIDS.     

Natural death as viewed by the medical examiner: a review of 1000 consecutive autopsies of individuals dying of natural disease

A study of 1000 consecutive autopsies of individuals dying of natural disease was conducted. Cardiovascular disease was responsible for 60.9% of all deaths with coronary artery disease--not only the main cause of cardiovascular death but also the main cause of all natural deaths--accounting for 45.1% of such cases. Diseases of the central nervous and respiratory systems accounted for 8.7 and 8.6%, respectively, of the natural deaths. Seizure disorders and pneumonia were the main causes of death in these organ systems. There were 124 deaths of children less than one year in age, 91 of which were due to sudden infant death syndrome (SIDS). All of the SIDS deaths were in children less than 10 months old.     

The validity of death certificates: routine validation of death certification and its effects on mortality statistics

The 3478 death certificates (7.1% of all annual death certificates) of this study comprise those national death certificates in 1995 submitted for validation to the panel representing both medical and nosological expertise. As such, it is highly selected and represents, from the nosological point of view, the most inconsistently filled-in portion of Finnish death certificates. The routine validation procedure is essentially based on exploitation of the extra medical information, i.e. the case history, on the Finnish death certificate form. Altogether, 2813 (80.9%) out of 3478 certificates could be adjusted at the primary panel session; the rest required further clarification. The re-assignment of cause of death by the panel and the impact of panel adjustments on the national mortality statistics is assessed here by comparing the initial death certification and the finally registered underlying cause of death grouped into ICD-9 major categories with special reference to the subcategories of neoplasm, cardiovascular disease (HVD) and unnatural death. A statistically significant decline (p<0.0001) in deaths, both in the category of symptoms, signs and ill-defined conditions and in the pulmonary circulation disease subcategory of HVD with 37.6 and 35.1%, respectively, was observed. The decrease of 11.1% in the benign or NUD neoplasm subcategory and the increase of 8.6 and 7.0% in the categories of endocrine disease, and musculo-skeletal and connective tissue disease, respectively, are essential observations as to the quality of the cause of death register. The effect on the HVD major category was practically nil. At the HVD-subcategorial level, a decrease of 14.0% for diseases of the veins and lymphatics and other circulatory diseases and an increase of 3.5% for hypertensive diseases (HYP) were the two next most obvious alterations to the diseases of the pulmonary circulation, but were without statistical significance. For ischaemic heart disease and other subcategories, the effects were minor. The unnatural deaths as a whole increased in the final statistics with only 0.9%. In the study data, categorial changes ranged from the decrease of 75.2% for symptoms, signs and ill-defined conditions to the increase of 77.3% for endocrine diseases. In conclusion, the Finnish death certificate form, death certification practices and cause of death validation procedure seem to serve the coding of causes of death for mortality statistics appropriately. The results of the study form a relevant reference background to evaluation of epidemiological studies on mortality.     

Sudden infant death in a tropical environment: Singapore's experience

A total of 206 cases of sudden infant deaths examined at the Institute of Science and Forensic Medicine, Singapore, over a 5 year period (1989–1993) were identified to assess the pattern of sudden death in this age group, which was subdivided into the neonatal and post-neonatal periods. A total of 34% (70) of infant deaths occurred in neonatal life and the remaining 66% (136) in the post-neonatal period; 90% of the neonatal deaths were natural, of which over half were due to congenital heart disease and complications of prematurity. Unnatural deaths in this period were uncommon, there being only seven such deaths. In the post-neonatal period, unnatural deaths constituted 25% of the total with trauma and aspiration heading the list. Natural deaths in the post-neonatal period are predominantly due to infections (34%) and a group of sudden natural deaths with minimal findings (31%). The latter group may arguably represent cases of Sudden Infant Death Syndrome (SIDS). The yearly incidence of this group in our study varied between 0.08 to 0.2 per 1000 live births, which is considerably lower than the incidence quoted for Western populations. The criteria for the classification and the impact of sudden infant deaths in Asian countries are discussed.     

Acallosal brain in sudden infant death syndrome (SIDS).

A definitive explanation of "crib" or "cot" death remains unknown. An unusual incidental autopsy finding of agenesis of the corpus callosum in a case presenting as "near miss" sudden infant death syndrome (SIDS) is discussed. Hitherto, only a single case associated with SIDS has been reported in the literature. The condition may be easily missed outside the interest in neuropathology.     

Changing trends in the diagnosis of sudden infant death

A study of 114 consecutive cases of unexpected infant death that occurred in South Australia over a 5-year period from January 1994 to December 1998 was undertaken. There were 45 deaths attributed to sudden infant death syndrome (SIDS), 19 to natural causes, 21 to accidents. and 5 to homicides; 24 cases were listed as "undetermined." Although there has been a genuine and continued decline in SIDS numbers in this population, there has also been an increase in the diagnosis of cases of accidental asphyxia due to unsafe sleeping environments and of cases in which the family background and autopsy findings suggested more complex mechanisms. The change in diagnostic profile has followed the introduction of more rigorous clinical history review, death scene examination, and autopsy testing. Thus, although diagnostic outcomes have altered in this population, it is more likely the result of more careful interpretation of the extensive investigations that are now undertaken rather than arbitrary reclassification.     

Sudden infant death syndrome: a subject of medicolegal research

During the last decade, much attention has been paid to the risk factors of sudden infant death syndrome (SIDS). Many researchers have demonstrated that infant-care practices are linked to the risk of SIDS. Prone sleeping, bed sharing, maternal substance abuse, and cigarette smoking have been reported to be significant potentially modifiable risk factors for SIDS. Despite the reports that the incidence of SIDS has decreased by 38% in the United States, it remains the leading cause of death in the first year of life. Deaths resulting from child abuse or neglect inflicted or permitted by their caretakers being second only to SIDS in infant mortalities and some recommendations regarding the differentiation of SIDS and child abuse have generated speculation that some cases of infanticide were misdiagnosed as SIDS. To reach a proper conclusion as to the cause and manner of death of an infant who died suddenly and unexpectedly, investigation must be thorough and professional.     

Simultaneous sudden infant death syndrome: a proposed definition and worldwide review of cases.

Epidemiologic studies of sudden infant death syndrome (SIDS), the leading cause of death of infants during the postperinatal period (7-365 days), have mainly focused on the deaths of single infants. Simultaneous sudden infant death syndrome (SSIDS), the death of a pair of twins occurring at the same time, has received limited attention within the medical community. To the authors' knowledge, this article is the first to describe the 41 SSIDS cases cited in the world literature from 1900 to 1998 by the location of death, a summary of the circumstances surrounding the deaths, and evaluation of these cases in terms of a proposed definition of SSIDS. This evaluation critiques whether the 41 pairs of SSIDS cases adhere to a newly proposed definition of SSIDS. Twin infant deaths must meet all three criteria to be considered SSIDS. The study found that only 12 pairs of twins met all three criteria (29.2%), nine pairs met two criteria (21.9%), alternative cause of death was offered in five pairs of twins (12.1%) and in the remaining 15 pairs (36.6%), only limited information was available; therefore, no conclusions could be reached.     

Cytomegalovirus-induced pneumonia and myocarditis in three cases of suspected sudden infant death syndrome (SIDS): diagnosis by immunohistochemical techniques and molecularpathologic methods

Immunohistochemical and molecularpathologic techniques have improved the diagnosis of myocarditis as compared with conventional histologic staining methods done according to the Dallas criteria. Additionally, immunohistochemistry and in situ-hybridization are able to demonstrate viral infection, e.g. cytomegaloviruses in salivary glands and lungs, locations both known to be involved in cytomegalovirusinfection. However, in many cases of proved cytomegalovirusinfection the cause of death remains unclear. We report on three children younger than 1-year of age, who died suddenly without prodromal symptoms. Their deaths were attributed to SIDS (sudden infant death syndrome). In situ-hybridization, immunohistochemical (LCA, CD45R0, CD68, MHC-class-II-molecules, E-selectine) and molecularpathologic investigations (PCR), however, suggested that death was caused by a cytomegalovirus-induced pneumonia or myocarditis. In the future, these methods should be used for investigating cases with suspicion of SIDS.     

The epidemiological study on registered cases of sudden infant death syndrome (SIDS) in Tokyo: examination of the effect of autopsy on diagnosis of SIDS and the mortality statistics in Japan

In the United States and most of European countries, a diagnosis of sudden infant death syndrome (SIDS) may be given only after an autopsy has been performed. Under the new definition of SIDS in Japan, an autopsy is now mandatory for the diagnosis of SIDS. However, according to the official records on autopsies, the proportion of autopsy for sudden infant death in Japan is still low (less than 30%). If a physician suspects SIDS from a review of the patient's medical history and medical findings, he can write 'suspected SIDS' as the cause of death on the death certificate without performing an autopsy. Such a clinical diagnosis is entered in the Vital Statistics section by the Japanese Ministry of Health and Welfare. In this report, a comparative epidemiological survey of registered cases of SIDS--after autopsy and with no autopsy--was carried out by examining the data from the death certificates registered by the Japanese Ministry of Health and Welfare (vital statistics in Tokyo from January 1979 to December 1996). There were 369 cases of SIDS registered in Tokyo. We found 247 diagnosed after autopsy (66.9%) and 122 with no autopsy (33.1%). The following epidemiological variables were used: address of the deceased (a specific area in Tokyo), sex, year of death, time of death, month of death, age at death, occupation of householders, and place of death. There were epidemiological differences at the 0.05 significance level between registered cases diagnosed after autopsy and those diagnosed without autopsies, as follows: year (P=0.016) and place of death (P=0.037). In addition, there were slight epidemiological differences at the 0.10 significance level between registered cases diagnosed after autopsy and with no autopsy, as follows: month of death (P=0.076) and age at death (P=0.082). This suggests that the quality of diagnosis of SIDS is not completely guaranteed. With respect to the area of residence, the incidence of SIDS is high in those areas where autopsy is performed frequently. In Tokyo, the medical examiner system is enforced only in the urban area and there is a possibility that SIDS is being underdiagnosed in the rural area of the Metropolitan Tokyo. It is likely that the diagnosis of SIDS without autopsy will influence the quality of SIDS diagnoses. The administrative inadequacy in the autopsy system in Japan should be corrected to improve the accuracy of SIDS diagnosis.     

Pulmonary siderophages and unexpected infant death

It has been proposed that the presence of siderophages in the lungs of infants who die unexpectedly should be considered a marker of a previous hypoxic event, which may preclude a diagnosis of sudden infant death syndrome. The authors retrospectively reviewed all infant deaths (<1 year old) going to autopsy at the Denver Office of the Medical Examiner from January 1999 to January 2001. Lung sections were stained with Prussian blue, and siderophages were counted in 20 high-power fields per lobe sampled. Cell counts were performed by two independent pathologists who were blinded to history and cause of death, with good reproducibility. Iron stain results were then categorized by average number of siderophages per 20 high-power field (category 1 = <5, category 2 = 5-100, category 3A = 100-500, category 3B = >100 in a single lobe, category 4 = >500). The results were subsequently correlated to case history, autopsy findings, and cause/manner of death. Forty-three cases were reviewed. The causes of death included sudden infant death syndrome (16), asphyxia (5), undetermined (6), and other (16). Those deaths were categorized by the above criteria as follows: category 1. (32), category 2. (6), category 3. (4), and category 4. (1). All sudden infant death syndrome deaths were in category 1. Categories 1 and 2 also included deaths in which hypoxia might have been present before death because of such factors as pneumonia and congenital heart disease. Categories 3 and 4 included a known homicidal asphyxia in which repeated episodes of intentional smothering were documented, 2 probable asphyxias, 1 nonaccidental trauma, and 1 undetermined. All 5 cases had questionable circumstances surrounding the death of the infant. Pulmonary siderophages were described in only 1 of the 43 autopsy reports. It was concluded that pulmonary siderophages can be markedly increased in cases of repeated asphyxia. Siderophages may also be increased in cases where hypoxia may have been present for another reason, but not to the same degree. Siderophages are not increased in sudden infant death syndrome. Because iron-laden macrophages often are not recognized on routine examination with hematoxylin and eosin staining, iron stains may be helpful in the evaluation of infant deaths. If siderophages are present in increased amounts without an obvious explanation, further investigation is warranted.     

Cardiac rhabdomyoma presenting as sudden infant death syndrome

A case of cardiac rhabdomyoma presenting as sudden infant death in a four-and-one-half month-old infant is reported. The child was the product of an essentially uncomplicated pregnancy and enjoyed good health before his unexpected, sudden death. Autopsy examination revealed the presence of multiple cardiac lesions which histologically were diagnosed as rhabdomyomas. Death was attributed to fatal cardiac arrhythmia caused by the tumor. To the authors' knowledge this represents the first reported case in the forensic science literature of death as a result of cardiac rhabdomyoma presenting as sudden infant death syndrome (SIDS).     

Investigation of sudden infant deaths in the State of Maryland (1990-2000)

The Office of the Chief Medical Examiner (OCME) has recorded a significant decline in the deaths of sudden infant death syndrome (SIDS) in the state of Maryland since 1994. However, infants who died of accidental or non-accidental injuries remained consistent during the same time period. This report focuses on the epidemiological characteristics and scene investigation findings of infant victims who died suddenly and unexpectedly in Maryland between 1990 and 2000. A retrospective study of OCME cases between 1990 and 2000 yielded a total of 1619 infant fatalities. 802 infant deaths were determined to be SIDS, which represented 50% of the total infant deaths in our study population. Five hundred and twenty-three (31.8%) deaths were due to natural diseases, 128 (7.9%) deaths were accidents, and 74 (4.6%) were homicides. The manner of death could not be determined after a thorough scene investigation, review of history and a complete postmortem examination in 92 (5.7%) infants. SIDS deaths most often involved infants who were male and black. The peak incidence of SIDS was between 2 and 4 months of age. The majority of SIDS infants (60%) were found unresponsive on their stomach. Among SIDS infants, 269 (33.4%) were found in bed with another person or persons (bed sharing). Of the bed-sharing SIDS cases, 182 (68%) were African-American. In the past 11 years, 52 infants died of asphyxia due to unsafe sleeping environment, such as defective cribs, ill-fitting mattresses, inappropriate bedding materials. Of the 74 homicide victims, 53 (70%) involved infants less than 6 months of age. Twenty (27%) exhibited the classical abuse syndrome characterized by repeated acts of trauma to the infants.     

The epidemiology of sudden infant death syndrome in Finland in 1969-1980

SIDS cases were defined by examining all death certificates, in which sudden deaths were expected to be found from the years 1969-80 from the Central Statistical Office of Finland. The age limits were 28-364 days. If the death certificate did not give enough information as to whether the cause of death was explained or unexplained, autopsy records and microscopic specimens were examined. If the death was sudden, but no autopsy was done, no microscopic specimens were taken, or there were some slight findings which could have partly explained the death were classified as borderline cases. The mean annual incidence of SIDS in Finland was 0.41/1000 livebirths in 1969-80. In 1969-74 and 1975-80 the incidences were 0.31 and 0.51, respectively. The increasing tendency of SIDS was partly due to more borderline cases in the first period and partly due to more twins, and infants with small birth weight, dying of SIDS in the second period. Deaths at weekends and sleeping with parents in the second period were more common than in the first study period. In the SIDs group the young maternal age, low social class, family type unmarried couple or single mother, maternal anemia during pregnancy were more common than in the control group. Mothers of SIDS infants had more previous children and fewer visits and later first visit to prenatal clinics than control mothers. The duration of gestation was shorter and the mean birth weight and length were smaller in the SIDS case than in the control group. Twins were more common among SIDS infants than in the common population. The most important risk factor of SIDS was maternal smoking during pregnancy. The epidemiological results conform with the hypoxia hypotheses.