External cause categories
Table 1 in the appendix tables describes the inclusions for each major external cause category and the relevant ICD-10-AM codes. The following notes also apply:
Additional information about external cause categories
The cases included are those involving unintentional drowning and submersion. Note that this does not include unintentional drowning and submersion injuries due to water transportation, other transportation crashes, or acts of nature such as storms and floods – unless the first-mentioned external-cause code is one of those listed above. Cases of ‘the bends’ due to deep diving and rapid ascents are covered in the Electricity and air pressure cause category. A discussion of terms such as ‘drowning’ and ‘submersion’ can be found in the WHO’s global report on drowning (2014).
Submersion: Brief submersion (or immersion) in water or other non-toxic liquid is usually harmless. However, injuries can occur while a person is submerged, particularly following a fall or dive into water. A submerged person may experience respiratory impairment (see ‘drowning’, below).
Drowning: Prolonged submersion (or brief submersion in some circumstances – for example, if a person is unconscious when entering the water), puts a person at immediate risk of death by drowning. The drowning process typically involves breath-holding; attempted inhalation triggering spasm of the larynx; depletion of oxygen and build-up of carbon dioxide; loss of consciousness; and, eventually, inhalation of water into the lungs.
Sometimes the process is interrupted before death (for example, by rescue), in which case the person may survive with harm, such as brain damage due to lack of oxygen. That situation was previously referred to as ‘near-drowning’ and is now called ‘drowning with a non-fatal outcome’, the term currently recommended by the WHO.
This category covers the ICD-10-AM code group ‘Other accidental threats to breathing (W75–W84)’, as well as W44 (Foreign body entering into or through eye or natural orifice) where a principal diagnosis indicates a likelihood that the hospital separation was principally due to a threat to breathing.
The external cause classification of foreign bodies with and without obstruction (or ‘choking’) is determined by the documentation within the clinical record and the hierarchy and essential modifiers of the ICD-10-AM classification.
If the documentation within the clinical record does not explicitly state ‘asphyxia’, ‘obstruction’ or ‘suffocation’ in relation to the foreign body, W44 must be assigned as the default code as indicated by the Alphabetic Index structure. A code from W80, W79 or W78 may only be assigned where there is clear documentation of the terms ‘asphyxia, obstruction, suffocation’ with a causal link to the foreign body.
For the purposes of this report, any case where the principal diagnosis is a foreign body in the mid-lower respiratory tract is considered a threat to breathing. Cases with a principal diagnosis of T17.2 – T17.8 (foreign body in pharynx, larynx, trachea, bronchus, or other and multiple parts of the respiratory tract), and an external cause of W44 are reported under the ‘Choking and suffocation’ category. In previous AIHW reports, these cases were reported under the ‘Contact with objects’ external cause category.
It is likely that some cases with a foreign body in the mouth or oesophagus (T18.0 & T18.1) and a code of W44 may also pose an accidental threat to breathing, however the majority will not. Therefore, these have been excluded from re-categorisation and remain in the ‘Contact with objects’ external cause group.
The technical description of this category is ‘Exposure to inanimate mechanical forces’.
A change in coding of Contact with knife, sword or dagger (W26) occurred between the 8th and 9th editions of ICD-10-AM and it was renamed Contact with other sharp object(s) (W26) and Contact with knife, sword or dagger became a subcategory (W26.0). The subcategories in W26 now include:
- Contact with knife, sword or dagger (W26.0)
- Contact with other sharp object(s), not elsewhere classified (W26.8) (including Edge of stiff paper and Tin can lid)
- Contact with unspecified sharp object(s) (W26.9).
In addition, the specific exclusion of ‘Knife, sword or dagger’ in Foreign body or object entering through skin (W45) is removed.
According to inclusion notes in ICD 10 AM, hospitalisations for injury should be assigned codes in the range X60–X84 if they were purposely self inflicted poisoning or injury, suicide, or attempted suicide (ACCD 2019c). Determining whether an injury is due to intentional self harm is not always straightforward. Cases may appear to result from intentional self harm, but the available information may be inconclusive and therefore preclude them being coded as intentional. In this situation, the case can be coded to an ‘undetermined intent’ category—for example, Falling, jumping or pushed from a high place, undetermined intent (Y30) or Crashing of motor vehicle, undetermined intent (Y32).
Some patients may choose not to disclose that their injuries resulted from intentional self harm. Some may be unable to do so due to the nature of the injuries. For others, their motives may be ambiguous.
In very young children, confirming that an injury was due to intentional self harm can be difficult and may involve a parent or caregiver’s perception of the intent. Ability to form an intention to inflict self harm, and to understand the implications of doing so, requires a degree of maturity that is absent in infancy and early childhood.
It is not possible to differentiate between acts of self injury and acts of self harm with suicidal intent within the NHMD, but it is likely that a proportion of cases of intentional self harm are self injurious in nature rather than suicidal in intent.
Due to the particular uncertainties around the intent of children, cases of intentional self harm are presented in aggregate for ages up to and including 18, and for aged 13–18.
As with injury due to intentional self-harm, cases of injury due to intentional assault may be difficult to identify. Feelings of shame or embarrassment may underlie reticence to report either of these forms of intentional injury. In addition, most injuries due to interpersonal violence have potential legal implications. Pressures or incentives to not reveal assault may be particularly likely in circumstances such as injury of a child or other dependent person by a caregiver, or injury of one spouse by the other. Cases recognised as possibly being due to assault—but where doubt remains—may therefore be coded as Undetermined intent.
Perpetrator codes are used in ICD 10 AM when a code from the ICD 10 AM category Assault (X85–Y09) is present. A coding standard (ACCD 2019c) provides guidance to clinical coders in assigning codes identifying the perpetrator of assault, abuse, or neglect. The coding rules operate on a hierarchical basis, with coders required to code the closest relationship between the perpetrator and the victim. The 10 subcategories of perpetrator consist of the following:
- spouse or domestic partner
- parent
- other family member
- carer
- acquaintance or friend
- official authorities
- person unknown to the victim
- multiple persons unknown to the victim
- other specified person
- unspecified person.
Injuries inflicted through legal interventions and operations of war (Y35 – Y36) are included under the assault category but do not form part of the perpetrator analysis.
Some injury cases do not include an external cause, or the only cause code provided is invalid for the scope of this report (i.e., supplementary factor codes). These cases are included in this report as ‘not reported’ and are counted towards to the total injury cases.