Understanding the Problem
About 3,500 US infants die suddenly and unexpectedly each year. We often refer to these deaths as sudden unexpected infant deaths (SUID). Although the causes of death in many of these children can’t be explained, most occur while the infant is sleeping in an unsafe sleeping environment.
Researchers can’t be sure how often these deaths happen because of accidental suffocation from soft bedding or overlay (another person rolling on top of or against the infant while sleeping). Often, no one sees these deaths, and there are no tests to tell sudden infant death syndrome (SIDS) apart from suffocation.
To complicate matters, people who investigate SUIDs may report cause of death in different ways and may not include enough information about the circumstances of the event from the death scene.
Interpreting Infant Death
Law enforcement, first responders, death scene investigators, medical examiners, coroners, and forensic pathologists all play a role in carrying out the case investigation.
A thorough case investigation includes
- An examination of the death scene.
- An autopsy (medical examination of the body after death).
- A review of the infant’s medical history.
Most SUIDs are reported as one of three types of infant deaths.
Types of SUID
- Sudden Infant Death Syndrome (SIDS)
SIDS is defined as the sudden death of an infant less than 1 year of age that cannot be explained after a thorough investigation is conducted, including a complete autopsy, examination of the death scene, and a review of the clinical history. About 1,500 infants died of SIDS in 2014. SIDS is the leading cause of death in infants 1 to 12 months old. - Unknown Cause
The sudden death of an infant less than 1 year of age that cannot be explained because a thorough investigation was not conducted and cause of death could not be determined. - Accidental Suffocation and Strangulation in Bed
Mechanisms that lead to accidental suffocation include:- Suffocation by soft bedding—for example, when a pillow or waterbed mattress covers an infant’s nose and mouth.
- Overlay—for example, when another person rolls on top of or against the infant while sleeping.
- Wedging or entrapment—for example, when an infant is wedged between two objects such as a mattress and wall, bed frame, or furniture.
- Strangulation—for example, when an infant’s head and neck become caught between crib railings.
Even after a thorough investigation, it is hard to tell SIDS apart from other sleep-related infant deaths such as overlay or suffocation in soft bedding. While an observed overlay may be considered an explained infant death, no autopsy tests can tell for certain that suffocation was the cause of death.
Shaken baby syndrome (SBS)
SBS is a constellation of medical findings (often referred to as a “triad”): subdural hematoma, retinal bleeding, and brain swelling from which physicians, consistent with current medical understanding, infer child abuse caused by violent shaking. In a majority of cases there is no visible sign of external injury. Shaken baby syndrome is a subset of the broader form of child abuse termed abusive head trauma. The Centers for Disease Control and Prevention identifies SBS as “an injury to the skull or intracranial contents of an infant or young child (< 5 years of age) due to inflicted blunt impact and/or violent shaking”.
Characteristic injuries associated with SBS include retinal bleeds, multiple fractures of the long bones, and subdural hematomas (bleeding in the brain). These signs have evolved through the years as the accepted and recognized signs of child abuse and the shaken baby syndrome. Medical professionals strongly suspect shaking as the cause of injuries when a baby or small child presents with retinal bleed,fractures, soft tissue injuries or subdural hematoma, that cannot be explained by accidental trauma or other medical conditions.
Retinal bleeds occur in around 85% of SBS cases; the type of retinal bleeds are particularly characteristic of this condition, making the finding very useful in establishing the diagnosis.While there are many other causes of retinal bleeds besides SBS, there are usually additional findings (ocular and/or systemic) which make the alternative diagnoses apparent.
Fractures of the vertebrae, long bones, and ribs may also be associated with SBS. Dr. John Caffey reported in 1972 that metaphyseal avulsions (small fragments of bone had been torn off where the periosteum covering the bone and the cortical bone are tightly bound together) and “bones on both the proximal and distal sides of a single joint are affected, especially at the knee”.
Additional effects of SBS are diffuse axonal injury, oxygen deprivation and swelling of the brain, which can raise pressure inside the skull and damage delicate brain tissue. Victims of SBS may display irritability, failure to thrive, alterations in eating patterns, lethargy, vomiting, seizures, bulging or tense fontanels (the soft spots on an infant’s head), increased size of the head, altered breathing, and dilated pupils.
