[Question #3580] Importance of Urine Sample Volume

34 months ago
Hi there Doctors, 

I have a question which i think i may know the answer to but just wanted to check with you. I am now happily married but have had STI tests in the past, both on the NHS (I live in the UK) and privately. 

When providing a urine sample the instructions are to provide between 10ml and 20ml of urine. However, there were occasions when i provided significantly less than this, perhaps even only 2 ml on a couple of occasions when i was struggling to go and up to 30ml on other occasions (always first stream however). 

Am i correct in thinking that PCR testing is so sensitive and accurate that the volume of urine provided is almost irrelevant to test accuracy and that even a small 2ml sample would still be ok? 

Many thanks 

Edward W. Hook M.D.
Edward W. Hook M.D.
34 months ago
 Welcome to our forum. Your question is a good one which I will be happy to address.  Despite rather specific instructions on the volume of urine to be provided for STD testing, these instructions are actually quite flexible and as long as sufficient urine is present to perform the test, the volume makes little difference.   Similarly, going slightly over the designated target volume of urine for specimen collection likewise has no meaningful impact on test performance.   You can have confidence in your previous test results.   EWH---