Laboratory Procedures and Specimen Collection Flashcards
7 cards from real CMT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Laboratory Procedures and Specimen Collection flashcards as text
The preferred method for collecting a urine specimen for routine urinalysis and culture is:
Answer: Midstream clean-catch
A midstream clean-catch specimen minimizes contamination from urethral flora by discarding the initial urine stream before collecting the mid-portion.
A 24-hour urine collection should be stored at which condition during the collection period?
Answer: Refrigerated at 2–8°C or with a specified preservative
Refrigeration at 2–8°C or use of the appropriate chemical preservative prevents bacterial growth and analyte degradation during the full 24-hour collection period.
On a urine dipstick, a positive nitrite result suggests the presence of:
Answer: Gram-negative bacterial infection
Many gram-negative bacteria convert urinary nitrates to nitrites via bacterial reductase, making a positive nitrite test an indicator of gram-negative urinary tract infection.
When collecting a stool specimen for occult blood testing, the patient should avoid which food for 3 days before collection?
Answer: Red meat and raw broccoli
Red meat contains hemoglobin, and certain raw vegetables contain peroxidases, both of which can cause false-positive guaiac-based occult blood tests.
Which technique is used to collect a throat culture for Group A Streptococcus?
Answer: Swab the tonsils and posterior pharynx while avoiding the tongue and teeth
Group A Strep colonizes the tonsils and posterior pharynx; swabbing there while avoiding contamination from saliva on the tongue and teeth yields the most accurate specimen.
A sputum specimen for culture should ideally be collected:
Answer: First thing in the morning before eating or brushing teeth
First-morning sputum contains the highest concentration of overnight accumulated secretions from the lower respiratory tract, improving diagnostic yield.
A wound culture specimen should be collected from which area of the wound for the most accurate results?
Answer: The deepest cleanest tissue at the wound base after cleansing
Collecting from the deepest viable tissue after surface cleansing avoids surface contaminants and identifies the true causative organisms rather than colonizing bacteria.