Pathology and sudden unexpected death in infancy

Abstract

The term 'sudden unexpected death in infancy' (SUDI) in the majority of cases describes infant deaths resulting from sudden infant death syndrome (SIDS or cot death) but infants dying unexpectedly from other, less common causes such as infection, trauma or a metabolic disorder are also included in this definition. Since the 'back to sleep' campaign was introduced in 1991, the number of SIDS deaths in the UK has fallen dramatically with only 442 deaths from this cause in 1993 compared to 1337 such deaths in 1989.1 Nevertheless, SIDS remains the most common natural cause of death in infants between one week and one year of age? A 2-year case-controlled study of sudden unexpected deaths in infancy in three health regions in the UK by the Confidential Enquiry into Stillbirth and Death in Infancy (CESDI) showed that 85% of sudden deaths occurred in babies of less than 6 months of age with an overall SIDS rate of 0.87 per 1000 live births. Of 128 SUDI cases investigated, 27 were not cot deaths. These included 5 accidents, 13 infections, 2 cases of metabolic disorders and 7 suspected nonaccidental injuries. This disturbingly high relative proportion of non-accidental injury-related deaths can be partially explained by the decline in number of cot deaths following changes in child care practices. The known risk factors for SIDS: young maternal age, male sex, prematurity, low birth weight and age between 6 and 18 weeks, were reinforced by the study. No clear seasonal pattern was demonstrated I and previously documented winter peaks in SIDS incidence are no longer apparent. The accepted definition of a cot death coined by Beckwith in 1970 describes 'the sudden death of an infant which is unexpected by history and in which a thorough post mortem examination fails to reveal an adequate cause of death'? It has been suggested recently that this definition should be modified to include investigation of the death scene and a review of the clinical history? The death scene investigation occasionally may reveal that the infant has been exposed to an unsafe sleeping environment such as an overheated room or to conditions which may compromise the infant's ability to breathe. Accidental suffocation is said to be more common in infants below one month of age but this does not correspond to the age when the majority of SIDS occur. 5 In practice not many sudden infant deaths have formal death scene investigations carried out, although the house is often visited by a Coroner's officer or investigating police officer. The professionals involved in the investigation of a particular case, including the police and Coroners, use their own judgement as to the extent of such investigations which may be necessary to provide the information pertinent to the final cause of death. The diagnosis of cot death is made by exclusion of all other possible causes of death in young infants. In 1971 this diagnosis was accepted as a registrable natural cause of death by the Society of Coroners and the Registrar General in Britain. 6