What does it mean if you are not able to pass urine for 2 days but feel like you have a full bladder?

Failure to void. . It is not normal to go for two days without passing urine. Failure to void is caused by obstruction of the bladder, or an inability of the bladder to contract and expel the urine. A buildup of a large volume of urine can damage your bladder and eventually your kidneys, as well and increase your chances of a urinary infection. Please see a physician for evaluation if this is the case.