TABLE 1

Definitions and Criteria for Assigning Cases to SUID Case Registry Categories

CategoryCriteria That Must Be Met
Unexplained: no autopsy or death scene investigation1. Death is unexplained.
2. No death scene investigation or post-mortem examination information reported.
Unexplained: incomplete case information1. Death is unexplained.
2. Incomplete death scene investigation or autopsy information reported (including reports pending further investigation).
3. Lack of detailed information about where and how the body was found OR 1 of 3 tests: (1) toxicology, (2) radiograph, and (3) pathology was not performed and documented. Pathology can include histology, microbiology, or other pathology such as genetic testing, but not solely gross examination.
Unexplained: no unsafe sleep factors1. Death is unexplained after complete case investigation.a
2. Death may or may not occur during sleep. For those deaths that occur during sleep, the sleeping environment is free of unsafe sleep factorsb or other suffocation or strangulation hazards.
Note: case may or may not have other potentially fatal findings, concerning conditions,c or competing cause of death, but how these factors contribute to death is uncertain.
Unexplained: unsafe sleep factors1. Death is unexplained after complete case investigation.a
2. Found in an unsafe sleep environment, but the role of the unsafe sleep environment in causing or contributing to the death is uncertain. Examples of unsafe sleep factors are soft objects or loose bedding (eg, pillow, blanket), not in a crib, portable crib or bassinette, shared sleep surface, found non-supine.
3. No factors that might indicate suffocation were present. No evidence of face pressed into or obstructed by soft bedding (eg, pillow, egg crate foam, sleeping bag, or couch), witnessed overlay, entrapment, or wedging.
Note: case may or may not have other potentially fatal findings, concerning conditions,c or competing cause of death, but how these factors contribute to death is uncertain.
Unexplained: possible suffocation with unsafe sleep factors1. Death is unexplained after complete case investigation.a
2. Scene investigation provides evidence of suffocation or asphyxiation caused by an external airway obstruction. Examples include overlay, entrapment or wedging, or face pressed into and airway fully occluded by soft bedding (eg, pillow, egg crate foam, cushion, sleeping bag, or couch).
3. Event was not witnessed or there was a conflicting account of full external obstruction of both nose and mouth, or external compression of the neck or chest.
 AND/OR
 Potentially fatal findings or concerning medical conditionsc were present at postmortem examination.
 AND/OR
 Although there was strong evidence of suffocation, suffocation does not seem probable given the infant’s age and likely stage of development (eg, otherwise healthy 11-month-old infant found face down on pillow).
Explained: suffocation with unsafe sleep factors1. Death is explained after complete case investigation.a
2. Scene investigation provides sufficient evidence of suffocation or asphyxiation caused by an external airway obstruction. Examples include witnessed overlay, entrapment or wedging, or face pressed into and airway fully occluded by soft bedding (eg, pillow, egg crate foam, cushion, sleeping bag, or couch). Suffocation must be probable given the infant’s age and likely stage of development.
3. Evidence of full, external obstruction of both nose and mouth or external compression of the neck or chest.
4. Event was reliably witnessed and there were no conflicting accounts of full external obstruction of both nose and mouth or external compression of the neck or chest.
5. Potentially fatal findings or concerningc medical conditions were not present at postmortem examination.
  • a Complete case investigation is defined by the components of the death scene investigation and autopsy that were documented in the case report. For death scene investigation, detailed information about where and how the body was found was available. For autopsy, all 3 tests were performed and documented: (1) toxicology, (2) radiograph, and (3) pathology. Pathology can include histology, microbiology, or other pathology such as genetic testing, but not solely gross examination.

  • b Safe sleep environment: supine position on a firm sleep surface including a crib, bassinet, portable crib, or pack-and-play. Sleep surface is free of soft objects, loose bedding, bumper pads, or any objects that could increase the risk for entrapment, suffocation, or strangulation out of the crib. Intentionally placing an infant to sleep in a car seat is considered unsafe. We derived these criteria from the 2011 AAP recommendations for a safe infant sleeping environment.23

  • c An example of a concerning medical condition is an infant who has fever, vomiting, and lethargy in the 72 h before death.