If Landis' backup urine sample is positive - and the backup or B-tests often confirm the original - Landis could be stripped of his title.

NPR: Landis Doping Allegations Give Cycling Black Eye

And - as in the case of middle distance runner Diane Modahl - incorrect storing of a urine sample may alter its chemical components.

BBC: Doping: Banned substances

Scarlets lock MacLeod was suspended in October from competitive action after a urine sample he supplied in January showed higher-than-permitted levels of testosterone.

BBC: Beattie says Scots behind MacLeod

They also made several changes in the wake of NL MVP Ryan Braun having his 50-game suspension overturned based on the chain-of-custody being broken with this collected urine sample.

FORBES: MLB Becomes the First League to Implement HGH Testing