The WRU will have to explain themselves to World Rugby over a suspected concussion suffered by George North against England on Friday.
The Northampton winger appeared to take two separate knocks to the head, one in either half, but after coming off in the first half, he remained on in the second.
World Rugby is particularly concerned about the second injury in the second half, and has called for a full report from the WRU.
“World Rugby has requested a full report from the Welsh Rugby Union (WRU) following an apparent head impact sustained by Wales wing George North in the second half of Friday night’s RBS 6 Nations match between Wales and England at the Millennium Stadium, Cardiff,” said a statement.
“North, who sustained the impact in the 61st minute of the match remained on the field and, having undertaken an initial review of the broadcast footage, World Rugby is seeking to establish from the WRU whether all concussion management protocols were appropriately followed.
“Concussion management and education is at the heart of World Rugby’s player welfare strategy designed to protect players at all levels of the game and promote the very highest standards of education, coaching and medical care.”
The Wales squad management issued a medical update on Saturday following the Six Nations opener at the Millennium Stadium.
“He passed head injury protocol tests that were carried out in the medical room in addition to an on pitch assessment,” the Welsh Rugby Union said via a statement.
“He also showed no signs and symptoms when follow up tests were carried out immediately after the game.
“While George is currently symptom free, retrospective video review of the second incident identified the mechanism of injury which was previously unsighted on the field of play.
“This review has warranted the medical team to manage the player as concussed although the player currently has no signs and symptoms.
“He will now undertake a graduated return to play protocol with multiple follow up cognitive and physical tests.”
Meanwhile, The WRU also revealed that prop Samson Lee suffered a concussion, Dan Biggar sustained a laceration to his forehead following an accidental collision with team-mate Gethin Jenkins and Leigh Halfpenny sustained a mild neck injury that will be treated by the medical team this week.