 [ Symptoms ] can doctors mistakenly think a urine sample is contaminated when it is actually an illness  the nurse called and said my sample was contaminated by i know i cleaned thoroughly and did not touch the cup before during or after and i did a clean catch is it possible that a bacteria or something made it appear to be contaminated [ Disease ] it is often a mystery once your urine leaves the office and heads to the lab over the years i have had sample contaminated by the lab spilled lost in transit how in the world can someone lose a cup of urine  or in some cases there were so many different bacteria in your urine many that are from the skin or vaginal area that an accurate result could not be determined it is best to do it again clean thoroughly pee a little bit and then stop then collect the specimen