Fisher has been struggling with a foot injury sustained on the eve of the premiership season and he missed the Saints' round 11 loss to West Coast before their bye last weekend.
He was a late withdrawal on Saturday evening in their 35-point win over Melbourne at the MCG.
Coach Scott Watters the Saints would have a clearer idea of their options in the next few days.
"He's managed that throughout the course of the year and at times has been unbelievably courageous in actually just getting to a game," Watters said.
"We'll have a really clear assessment of that come Monday or Tuesday and we'll make a decision on how we manage Sam for the rest of the year.
"The docs will tell me that [if surgery need to be considered] come Monday or Tuesday so once we have a really clear understanding of where that's at, we'll make the best decision for him long term."
Watters also said ruckman Ben McEvoy appeared fine after being subbed out of Saturday night's 35-point win over the Demons following a high hit from Jake Spencer in the second quarter.
Spencer was reported for the high contact and McEvoy tried to prove his fitness on the boundary before being subbed out in the third quarter.
Watters said his ruckman was "clear-eyed" after the game and considered the impact to have been "very minor".
