Measuring hourly urine output

[ladydanger]

At my hospital we use Bard products. There is a hard plastic reservoir in the front separated into 2 sections one holding 50cc of urine and the other 350cc. This is attached to the traditional soft plastic bag. I am a fairly new nurse, and I apologize if this is a stupid question. However, the other day I was assessing hourly urine output and documenting it on my flow sheet. At the end of the shift when I dumped and measured the urine, the actual vs. measured output was 80cc off. When measuring hourly output, I was adding up the urine in the 50cc chamber to that in the 350cc chamber. I am not sure this is the correct way to perform this task. When I saw what I thought was 400cc of output when I actually emptied it, it was 350cc. Am I just suppose to look at the larger 350cc compartment if the 50cc is completely full and not add the 2 numbers together?

[MunoRN, RN]

The urometer box is split into two columns; a 50ml column to the right and 300 ml on the left. The larger left column is a continuation of the 50 ml column, so it starts at 51mls and goes to 350 mls. If the left column shows 250mls, then that is your total including the 50mls in the right column, do not add that 50mls to whatever total the left side is showing.