ECM Testing

The ECM test (Enriched Culture Medium test) for detecting group B Strep carriage is recognised as the ‘gold standard’ and has been described by Public Health England’s UK Standard (UK SMI B58) since 2006.

ECM testing involves taking samples from the lower vagina and rectum after 35 weeks of pregnancy, and usually by 37 weeks (they can be done earlier, but then may not be as reliable in predicting GBS carriage at delivery. If done later, there is an increasing chance that the baby will be born before the result is available). The samples are then sent to a laboratory, where they are processed using enrichment culture media to enhance the growth of GBS (click here for more information about ECM tests).

ECM testing is currently the best test for group B Strep on the market – recognised as the ‘gold standard’ for detecting GBS carriage, it is highly sensitive and has been used as the standard test for GBS carriage for decades in many developed countries.

The ECM test is rarely available within the NHS (though do ask your trust – it may just be one of those that do offer it).

The Royal College of Obstetricians & Gynaecologists’ Audit of current practice in preventing early-onset neonatal group B streptococcal disease in the UK reported that 55.9% of maternity units offer testing for group B Strep carriage to pregnant women based on risk factors or maternal request (3.7% of maternity units offer universal screening), but very few use the ECM test.

We don’t offer ECM tests, but can signpost you to reputable organisations that do. We endorse the availability of sensitive testing for GBS carriage. We receive no commission from the sale of GBS tests, nor referral fees. We hope that more organisations will offer GBS-specific testing – including NHS hospitals and laboratories – and will provide details as they do.

Private Laboratories

The ECM test is available privately from around £35 per test for a home-testing pack.

The organisations below follow the ECM methodology described by the Public Health England’s UK SMI B58, and the processing of the tests is undertaken by CPA accredited laboratories.

[Please note that the charity simply provides the name and address of laboratories – we don’t have the resources to check their performance in terms of speed or accuracy. If anyone would like to provide us with feedback on the services provided, please email us at]

The cost of the home testing pack, processing the swabs and sending you the results is approximately £35. You can watch a YouTube video about self-testing here.

Home Testing Services

Name Telephone Email Website
The Doctors Laboratory* 020 7307 7373
Blue Horizon Medicals 0800 098 8751
Medichecks 0845 602 9029
Medisave 0800 804 6447
Group B Strep Test
MedLab Pathology (Republic of Ireland) 1800 303 349

*Health professionals can order multiple test packs without charge (the pregnant mum pays the laboratory when she sends her swabs back for culture). You can also order a test by text – text ‘GBS’ to 88020 to order home-testing pack, and pay when you send the swabs back for processing.

Orders for the GBS Test Pack from a private organisation are usually sent out the same day. Samples can be taken by the pregnant woman herself, following the simple instructions provided – most women do this without difficulty. Or you can ask your health professional, who may charge a fee for sample collection. You should send back the samples the same day you take them, and keep the information leaflet that came with the pack for future reference. The lab will send out the results within 3 working days of receiving your samples.

Please ensure your health professional is also sent a copy of the results – the return forms allow space for you to provide contact details. You can opt to receive your result by SMS text message, as well as by post.

  • A GBS GREEN message means the result for GBS is NEGATIVE and intravenous antibiotics are not indicated.
  • A GBS RED message means the result for GBS is POSITIVE during your pregnancy and intravenous (not oral) antibiotics should be offered from the onset of labour and then at intervals until delivery.

If you are or have recently been taking antibiotics, please be aware this may affect the result of your GBS test. Please discuss this with your health professionals.

Testing at a Private Clinic

The following laboratories provide a personal service for ECM GBS testing, following the Public Health England’s UK SMI B58. Make an appointment to see them and they will take the swabs for you (or you take them yourself if you prefer that) and will send you the results by post, email or text. Their charges will be higher for this personal service.

Name Address Telephone Email
The Doctors Laboratory Patient Reception, 55 Wimpole Street, London W1G 8YL 020 7307 7383
Innermost Healthcare Ash Tree Medical Clinic, Woodsy Close, Cardiff CF23 8RW 0345 230 3386
Brandwood Clinic Shelly House, Farmhouse Way, Monkspath, Solihull, West Midlands B90 4EH 0121 296 9280
3fivetwo 352 Lisburn Road, Belfast BT9 6GJ 0845 60 06 35
Lanes Practice** Plough Lane, Stoke Poges, Bucks SL2 4JW 01753 662244
Well Woman and Baby Room 7 Basepoint Business Centre @ Ropetackle, Little High Street, Shoreham by Sea, West Sussex BN43 5EG 07913 208149
Alpha Healthchecks Unit 5, Howbury Technology Centre, Thames Road, Dartford, Kent DA1 4RQ 01322525180 / 07412103484

**You can also pick up home-testing packs from this practice.

What does the ECM test involve?

Two swabs are taken – one from just inside the vagina and the other from the rectum (the home-testing packs contain straightforward instructions).

Once the samples are taken, the swabs should be sent the same day to the laboratory (with payment) in the reply-paid envelope provided as part of the GBS home testing pack. Each of the above laboratories undertakes to send the results out within three working days of their receiving the swabs to the pregnant woman and, provided details are given, to her health professional.

As there is no post on Sundays, it may be preferable to take and send off the swab samples earlier the week.

Since the test packs, the swabs for culture and the results are sent through the post, the postal ECM GBS test can be done anywhere in the UK.

Group B Strep Support endorses the availability of reliable prenatal GBS testing. Group B Strep Support is completely independent – we receive no funding from the Government or the NHS, and we do not accept commission from the sale of GBS tests, nor fees for referring to other organisations. We hope that more laboratories will offer GBS-specific testing – including NHS laboratories. As they do, we’ll provide details of their service here.