The loose-head prop pulled up with a knee injury during Cardiff Blues' Heineken Cup victory over Racing Metro yesterday.
Jenkins will join Wales' Six Nations training camp in Poland today, but could be in a race against time to face Ireland on February 5.
"It's very early to say and we'll get more information over the next 24 to 48 hours," said Blues backs coach Gareth Baber.
"He's tweaked a ligament in his knee. Whether he's just hurting a little bit and it will sort itself or whether it may be something further.
"For him to come off a rugby field is not normal. He's disappointed that he's got to spend the next 24 or 48 hours looking after his leg."
Jenkins is the latest concern for Gatland, who is already without 2009 Lion Alun Wyn Jones and World Cup stars Luke Charteris and Lloyd Burns.
Rhys Priestland and Dan Lydiate also joined the casualty list in this weekend's European action.
Fly-half Priestland, who made the number 10 jersey his own during World Cup, limped off with an injury to his left knee a during Scarlets' victory over Castres.
"His knee is a bit sore, but we really can't tell at this stage," said Scarlets head coach Nigel Davies following the game.
"He's pretty chirpy. He's walking around pretty well, so hopefully it's not serious."
Lydiate was also helped off during Newport Gwent Dragons Amlin Cup win over Cavalieri Prato. The flanker was plagued by similar problems throughout the World Cup.
"Dan took a knock to the ankle early on, he will have scans now and then the Welsh physios will now make a further assessment when he joins up with them," said Dragons head coach Darren Edwards.
"He's been walking about in the changing room and has said it feels okay so we are hopeful there is nothing too serious."