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Group B streptococcus screen

Fertility and pregnancy · also printed as GBS, Group B strep, Group B streptococcus, GBS swab, Strep B

Typical UK adult rangeExpected result: Negative

Negative is the usual result; a positive leads to antibiotics in labour.

What this test measures

Group B streptococcus is a common bacterium carried in the vagina and bowel by around one woman in four. It is harmless to the carrier but matters around birth.

Why doctors request it

Not routinely screened in the UK, but found on swabs taken for other reasons in pregnancy, or requested privately.

What commonly pushes it up

What commonly pushes it down

Everyday reasons for a value outside the range

About the sample

No fasting needed.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.

Got a report with Group B streptococcus screen on it?

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This is an educational summary of results you uploaded. It is not medical advice, a diagnosis or a treatment plan, and it does not replace the doctor who requested the test. If you are worried, or a result is marked outside range, discuss it with your doctor. Written and reviewed by a UK consultant physician. Reference ranges vary between laboratories.