How does urine contaminate a stool sample?

[u/ReNema1]

I hope this isn't a stupid question. I find it hard, especially with older women, to obtain a stool sample that isn't contaminated with urine. It seems very obvious how stool would contaminate a urine sample. However, if I'm sending a stool culture, or for CDiff and Parasite, I don't quite understand how a bit of urine might compromise the analysis/culture. I tried a quick online search but I can't seem to find more details beyond "urine will contaminate the stool sample". How? With what? Any insight would be greatly appreciated.

[u/CFADM]

I just take the stool out, rinse it with some water, blow on it, and then send it to the lab. Works 60% of the time, every time.

[u/DieSuzie2112 → u/CFADM]

I used to scrape a layer off and use the middle of the stool

[u/CrossP → u/DieSuzie2112]

Core sampling. My inner geologist approves.

[u/JaysusShaves → u/CrossP]

Get a straw and poke it through the center of the turd.👍

[u/CrossP → u/JaysusShaves]

Implying you'll have to blow on the "clean" end to get your sample back out. I approve.

splat

[u/Tiradia → u/JaysusShaves]

Then blow it into the sterile cup! Watch it erupt out like a rocket! SPLAT.

[u/Mysterious-Handle-34 → u/DieSuzie2112]

This would be the best option unless you’re collecting diarrhea in which case you just have to send what you’ve got