What it measures
A check of the chromosomes in blood cells: how many there are and whether any are missing, extra or rearranged. The result is written as a short formula, such as 46,XX or 46,XY.
Why people test it
- Used when looking into repeated pregnancy loss.
- Used when looking into infertility, including very low sperm counts.
- Checked when a chromosome difference is suspected or runs in the family.
Typical range
Reported as a written description of the chromosomes, not a number; 46,XX and 46,XY are the usual results. Labs differ in how many cells they count and how closely they look, and the report says what was done.
Finger-prick or vein?
Offered as a vein draw only. The lab grows living white cells from the sample before reading the chromosomes, so it needs a fresh vein sample, which is also why results take weeks.