Sample collection and preparation
How each type of sample is collected — blood from a vein or a finger, urine, stool, saliva, swabs — and the everyday mistakes that distort results. Laboratory instructions always take precedence.
Blood from a vein
The standard way blood is taken for most laboratory tests — from a vein on the arm, in a few minutes.
Finger-prick blood test
A drop of blood from a fingertip — enough for glucose meters and a number of rapid tests.
Urine sample
A single portion of urine for a urinalysis — the clean-catch midstream method keeps the sample honest.
24-hour urine collection
Every portion of urine over a full day, kept cold in one container — the daily totals no single sample can show.
Stool sample
A small sample collected at home with a kit — most often to look for hidden blood in the stool.
Saliva sample
Spit or a mouth swab instead of a needle — used for hormones such as cortisol, often late in the evening.
Swab test
A soft brush on a stick collects cells and microbes from a mucous surface — the throat swab is the classic example.
Skin scraping
A small scrape of the affected skin, examined under a microscope with KOH — the quick test for a fungal infection.
Midstream urine sample
The clean-catch technique taken seriously — the version of a urine sample used when a culture must not be contaminated.