Scans and medical checks have shown that the Dutch midfielder, 28, damaged the anterior cruciate ligament in his right knee during the 1-0 victory over Leeds United.
Kieftenbeld had to be taken off on a stretcher in the 57th minute and was clearly in discomfort after suffering the injury in a tackle with Kalvin Phillips.
Kieftenbeld's contract is due to expire in the summer of 2020.
However, in the light of this personal setback to one of Blues most influential and popular performers, the Club are looking to trigger the option year in his deal.
Saturday was Kieftenbeld's 163rd appearance for Blues since joining from Groningen in July 2015 for around £200,000.
Over his four seasons at Blues to date he has proven himself to be a key cog in the midfield with his tenacious drive and energy infectious on those around him.
The Club's medical, physical performance and sports science departments will provide Kieftenbeld with the best possible expertise and support during the post-surgery rehabilitation process.