Stewart joined Swindon on a season-long loan deal this summer but the midfielder has now made a premature return back to Merseyside after suffering a medial ligament injury during the Football League Trophy clash against Newport on Tuesday.
As a result, Stewart has headed back to Anfield for treatment and is expected to be out for around six weeks.
Nonetheless, Swindon manager Mark Cooper is hopeful of Stewart's return to the County Ground, saying: "We'll see. We'll have a chat with Liverpool and see what they want to do. Brendan was here today so we'll see what they want to do. He's a good player, Kev. He can play in a lot of positions, so we'll have to make do."