What is a normal post-void residual urine?
There is no definite cut-off between what is clearly normal and clearly abnormal, nor a value above which management targeted towards reducing the residual urine (e.g. by catheter drainage) should be implemented. In older people with less effective bladder emptying, there is a greater tolerance for higher values. In general, < 50 ml would be regarded as acceptable, 50 200 ml abnormal but, depending on the clinical situation, not necessarily requiring further investigation, and >200 ml clearly abnormal. However, even for a value of > 200 ml further assessment and treatment may not necessarily be undertaken e.g. in a frail older person living alone who would not be able to manage catheter care, or who would not be a candidate for any surgical intervention.
