Can I find out if I carry GBS?

Reliable testing for GBS carriage is not available on the NHS – the standard test which is sometimes offered on the NHS (often called an HVS) is not very reliable since up to 50% of women who are carrying GBS when the swabs are taken will falsely be given a negative result. However, a positive result from a HVS test is highly reliable.

The Enriched Culture Method (ECM) test, recognised as optimal for detecting GBS carriage by both the Royal College of Obstetricians & Gynaecologists and by the Health Protection Agency, it is not available routinely or on the NHS. However, it is available privately, and costs £35.00 (although some health professionals may also charge you for specimen collection). This test is much more sensitive and has been specifically designed for the isolation of GBS. MumStuff offer this test kit FREE of charge.

The ECM test should be performed at 35-37 weeks’ gestation to best predict colonisation with GBS at delivery since GBS carriage can be intermittent. Research shows that, if the ECM test is performed within 5 weeks of delivery, a negative result is 96% predictive of not carrying GBS at delivery (so 4% of women acquired carriage between the test and giving birth) and a positive result is 87% predictive of carrying GBS at delivery (so 13% of women lost carriage between performing the test and giving birth).

Any test result positive for GBS during pregnancy means that the pregnant woman should be offered intravenous antibiotics from the onset of labour or waters breaking and then 4-hourly until delivery.

A negative ECM test result means that the pregnant woman does not need to be offered intravenous antibiotics from the onset of labour or waters breaking against GBS infection in her baby.

Where no ECM test result is available OR the less reliable NHS test has come back negative, then the pregnant woman should be offered intravenous antibiotics during labour against GBS infection in her baby if one or more risk factors is present.

The ECM test has only been available in the UK since 1st May 2003 so many health professionals may not yet be aware of its availability. You can download the leaflet and give this to your health professional if they don’t already have it and find out more about this test on the GBSS website – see link below.

Reproduced with kind permission of Group B Strep Support.

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