With player safety a prominent concern in professional rugby, the Rugby World Cup again sees the head injury assessment (HIA) protocol in place.

The HIA protocol is a three-stage process introduced by World Rugby for elite adult teams to assist with the identification, diagnosis and management of head impact events with the potential for a concussion. There is no HIA in the community game.

A temporary replacement for head injuries was introduced into law in August 2015.

The most prominent of the three stages is HIA1, which occurs during a game.

Players who sustain head impact events with the potential for a concussion are identified by match officials, team doctors (TD), or independent match-day doctors (MDD), either during live action or on video review.

Players displaying obvious on-pitch signs of concussion are immediately removed permanently.

Where these are not displayed but a concussion still a possibility, the player departs to undergo an off-field assessment by an attending doctor and is replaced by a temporary substitute.

The assessment occurs in a set period of 12 minutes of absolute time, rather than game time.

The result of the assessment is compared to a previously conducted “baseline assessment” to assess whether a concussion is likely to have been suffered.

The assessment includes a test of Immediate Memory and Delayed Recall, and balance tests.

If the player fails their HIA1, their replacement becomes permanent and they take no further part in the game.

In the three hours after the match, every player entered into the protocol undergoes an HIA2 assessment to assess progress and identify an early diagnosis of concussion.

HIA3 is conducted after two nights of rest to further determine progress or identify a late diagnosis of concussion.

Under changes made by World Rugby last summer, there is now a 12-day stand down period for a player who has a history of concussion or was removed from a match after showing clear symptoms.

Any player eligible to return in a week – someone who has failed an HIA but subsequently has normal test results and no history of concussion – can only do so with the approval of an independent concussion consultant.