The Ghanaian has been a subject of transfer speculations this summer, having reportedly completed a medical at newly-promoted Premier League outfit Huddersfield Town ahead of a proposed move.
Although the medical reportedly took place on Friday, a deal agreement is yet to be announced as the Tykes host Nottingham Forest in the Championship on Tuesday.
“In my eyes I don’t have Yids until I’m told different,” Heckingbottom told BBC Radio Sheffield.
“As far as I know, nothing has really progressed. Both sides are talking.
“It wasn’t right for me to involve him on Saturday and if it is still the same I won’t on Tuesday because it isn’t fair on all the other players.
“We are preparing for our game and obviously [the player] is in limbo at the minute."
The fullback has already made two appearances for Barnsley this season, adding to his 32 league outings last campaign.
He was in action as the Tykes succumbed to a 3-1 defeat to Bristol City in the Championship opener, before seeing another full-time action in their 4-3 League Cup win over Morecambe.
The London-born, however, sat out Saturday's 2-1 defeat to Ipswich Town.
"Until it is resolved one way or the other and I'm told, I'm not considering him," Heckingbottom added.
"It isn’t fair on the players in the dressing room. It can’t go on much longer.
“I’m not thinking about it until after the game on Tuesday. I would expect to know on Wednesday or Thursday.”
Yiadom joined Barnsley from Barnet in summer last year, having also played for Braintree Town and Hayes &Yeading FC.