Carbery, 22, suffered a fracture on his left forearm after being tackled by Fijian prop Peni Ravai on the hour mark of a game the Irish narrowly won 23-20 in the second of their three-test November schedule.
"We will update on Monday but that would mean he will not play any part in the tests for us," Schmidt told reporters.
Carbery, chosen at flyhalf despite usually playing fullback for Leinster, was also injured in June playing test rugby. He suffered ankle ligament damage in Ireland's 55-19 away win over the United States and missed two subsequent tests in Japan.
Ireland, playing with a second string line-up, secured victory over Fiji with a penalty eight minutes from time.
"We wanted to see the players react under pressure. We got that at 17-all, and 20-all," Schmidt said.
"We stayed calm enough to control that last 10 minutes. I thought Ian Keatley did really well to come in and kick the two goals, particularly the second kick he struck really well."
Ireland complete their autumn internationals schedule at home to Argentina on Saturday. They began on Nov. 11 with a 38-3 thrashing of South Africa and Schmidt is expected to restore the majority of that line-up for their final game of 2017.
(Reporting by Mark Gleeson; Editing by John O'Brien)
