The 28-year-old picked up his 25th Test cap during Ireland's Grand Slam defeat to England two weeks ago after battling back into the side after long spells on the sidelines, but the injury to his right ankle in London Irish's 14-12 win over Saracens looks like seriously scuppering his chances of making October's World Cup in Australia.
Bishop – who took John Kelly's place on the Ireland wing recently – left the field in the 67th minute of the Zurich Premiership match, and even if he does recover to something near full fitness immediately before the World Cup, whether or not the management would be ready to thrust him into action remains a major question mark, with the June warm-up matches certainly coming too quickly for his rehabilitation.
"Justin’s talent, commitment and personality will be much missed over coming week," said London Irish managing director Conor O'Shea, a former Ireland star himself.
"We wish him a successful operation and a speedy recovery, and look forward to seeing him back on the pitch as soon as possible."
The exact description of Bishop's injury is a "fractured dislocation", with a surgeon due to run the rule over the joint early this week before deciding when the talented wing man should go under the knife.
Ireland already have a number of their players affected by long-term injuries, with hooker Keith Wood and openside David Wallace both playing no part in the Six Nations this year, while wing Shane Horgan has also been battling persistent problems.
Should Bishop fail to make the World Cup then the likes of John Kelly and fullback Geordan Murphy could slot in to the No.14 shirt, with Leinsterman Denis Hickie having occupied the left-wing so well of late.
Leinster's Gordon D'Arcy and Munsterman Anthony Horgan could be among the players in with a shout of a squad place, with a handful of others also in the international mix.