Ulster are currently second in the RaboDirect PRO12 table following an impressive victory in Dublin over Leinster last time out and face Newport Gwent Dragons this weekend as they look to seal a home semi-final.
But Anscombe is adamant that he will do whatever is right for Marshall rather than risk the player's safety.
"Let the medical team, who are experts in that, tell us this week what the story is," Anscombe told the Belfast Telegraph.
"It's a concern but we have good medical people involved in this team and we'll do everything that's right for Luke.
"We didn't rush him back; he had to prove that he was right to play.
"Stuart Olding has been doing a great job for us - you saw that when he came on - and my point is that we wouldn't have rushed Luke back if he wasn't ready."
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