Hello and welcome to HCM.
Thank you for your query.
The best solution as of now is to drink plenty of water, and this would obviously be required before the test as well, in order to dilute your urine.
As we are unaware about the cause and you do not have enough time to diagnose or treat this condition, I would also advise you to consume cranberry juice (which helps in case of infections). Although the cause for blood in urine should always be further investigated, if you wish to do so an abdominal and pelvic ultrasound
could give us an idea on the cause.
Our options certainly are limited without information on the condition. Wishing you luck for your selection. Do visit a doctor immediately after this, if you do not wish to do so before.
I hope I have succeeded in providing the information you were looking for. Please feel free to write back to me for any further clarifications. I would gladly help you.