In the context of specimen collection, what must patients avoid when providing a stool sample?

When providing a stool sample, it is crucial that patients avoid contaminating the sample with urine. This is because urine can introduce unwanted substances and bacteria into the stool specimen, potentially compromising the accuracy of the test results. For many stool tests, including those for infectious diseases or gastrointestinal issues, the purity of the sample is paramount for diagnostic purposes. Contamination may lead to false positives or negatives, ultimately affecting the patient's diagnosis and treatment plan.

In terms of the other options, while they certainly involve important aspects of specimen collection, they do not directly impact the integrity of the sample in the same way that urine contamination does. Consuming solid foods before the test or using non-sterile containers could lead to other issues, but they aren't as critical as ensuring that the stool sample remains uncontaminated. Additionally, bringing the sample to the facility late might affect the timeliness of the testing but does not compromise the integrity of the sample itself. Therefore, avoiding contamination with urine stands out as the most important factor in ensuring the validity of the stool sample.