My cat has blood in his stool

[Freedom]

Take a "fresh" stool sample with you. Yes, do go. Four more days is too long to wait.

[pomtzu]

Yes - definite cause for concern and action. It could be something simple like a broken vein (maybe from straining, etc?), yet could be a more serious issue too. Bright red blood means that it's closer to the end of the intestine, and not further up toward the stomach (then it would look very black and tar-like).

[phesina]

Yes, definitely give the emergency vets a call.

[Medusa]

Ditto to all the posts. Please update us when you can.