QCM : Sample Handling and Preservation Techniques — 9 questions

Explication

The source explicitly states that photosensitive samples must be shielded from light throughout transport to preserve their integrity, making this the correct practice. Recording incidents and proper labeling are also important but are not specific to photosensitive samples' light sensitivity. Transporting containers vertically is not recommended; horizontal positioning is preferred.

Explication

Incomplete coagulation prior to centrifugation results in fibrin formation, which can contaminate the serum sample and interfere with accurate laboratory testing, as explicitly described in the source.

Explication

Controlling temperature changes during sample handling can prevent thermal shock, a known cause of hemolysis. The source states that light exposure does not cause hemolysis, so exposing samples to light is not a preventive practice. Delaying centrifugation increases hemolysis risk, not decreases it. Using a smaller needle may reduce pain but does not directly prevent hemolysis caused by temperature or handling issues.

Explication

First morning urine samples are more concentrated in chemical constituents and formed elements, and they are less influenced by recent dietary intake, providing a more accurate baseline assessment. The source states that these samples tend to have higher osmolality, not lower, and are more, not less, concentrated.

Explication

The source specifies that the recommended abstinence period before semen collection is between 2 and 7 days, not just 24 hours, to ensure the sample's quality and reliability for fertility assessment.

Explication

Controlling light conditions during the measurement of porphyrins and vitamin D is essential to prevent degradation or alteration of these analytes, ensuring accurate and reliable test results.

Explication

The source explicitly states that confirming patient identity is a mandatory part of sample collection to prevent errors, whereas contamination considerations are more related to handling practices and are not described as mandatory verification steps. Therefore, confirming patient identity is a more critical, obligatory aspect compared to contamination considerations, which depend on collection and handling.

Explication

The fecal odor mainly comes from microbial processes in the gut that break down and modify compounds like bilirubin. The pigments stercobilin and urobilin contribute to color but are not responsible for the smell. Iron content does not significantly influence fecal odor, and chemical reactions unrelated to microbes are not indicated as primary odor sources.

Explication

The establishment of specific storage guidelines, such as maintaining CSF samples at 35±2 ºC or room temperature to preserve pathogen viability, reflects advances in microbiological diagnostic standards. These protocols became more standardized and widely adopted in the late 20th century, particularly in the 1980s, when microbiology and clinical pathology practices were significantly refined.