ECM Testing

The enriched culture medium or ECM test is the ‘gold standard’ for detecting group B Strep carriage, described by Public Health England’s UK Standards for Microbiology Investigations B 58. Samples are taken from the lower vagina and just inside the rectum using a swab, and these samples are then cultured using enriched media that encourages the growth of GBS. The test is usually done around 35-37 weeks of pregnancy (click here for more information).

Despite the Public Health England’s UK Standards for Microbiology Investigations B 58 having been published since 2006, few NHS trusts offer the ECM test, as confirmed by the first report of the Royal College of Obstetricians & Gynaecologists Audit of current practice in preventing early-onset neonatal group B streptococcal disease in the UK. This audit reported that 55.9% of maternity units offer testing to pregnant women based on risk factors or maternal request, and 3.7% of maternity units offer universal screening. However, it also reported that very few units use the ECM test methodology.

Private Laboratories

If your trust does not offer the ECM test, it 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 Standards for Microbiology Investigations B 58, and the tests themselves are undertaken by CPA accredited laboratories. A home-testing service is available. The cost of the test pack, processing the swabs and sending you the results is approximately £35. You can watch a YouTube video about self-testing here. You can obtain your ECM GBS test pack by contacting the following:

Name Telephone Email Website
The Doctors Laboratory* 020 7307 7373
Blue Horizon Medicals 0800 098 8751
Medichecks 0845 602 9029
Medisave 0871 288 4380
Group B Strep Test
Well Woman and Baby Room 07913 208149
MedLab Pathology (Republic of Ireland) 1800 303 349
Alpha Healthchecks 01322525180 / 07412103484

*You can also text ‘GBS’ to 88020 to order your text pack, paying when you send the swabs back for culture.

*Health professionals may request multiple testing packs without charge – the pregnant mum pays the laboratory when sending the swabs back for culture.

[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]

Orders for the GBS Test Pack from a private firm are usually sent out the same day. Once received, then the swabs can be taken either by the pregnant woman herself (following simple instructions provided in the pack – most women do this without difficulty), or by her health professional (who may charge a fee for the sample collection).

You should ensure that your health professional is also sent a copy of the results – the form allows space for this information to be given. When you complete the request form to send the swabs off for processing, you can opt to receive the result by SMS text message. 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.  Turnaround time for the results is within three days of receipt of your swabs at the laboratory.

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.

Tests at a Private Clinic: The following laboratories provide a more personal service for ECM GBS testing, whilst still following the Public Health England’s UK Standards for Microbiology Investigations B 58. You can make an appointment to see them; they can take the swabs for you (or you take them yourself) and will send you the results by post, email or text. Their charges may be higher for this personal service. These laboratories are:

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, B90 4EH 0121 296 9280
3fivetwo 352 Lisburn Road, Belfast, BT9 6GJ 0845 60 06 35
 Lanes Practice  The Lanes Medical Practice, Plough Lane, Stoke Poges, SL2 4JW  01753 662244
Alpha Healthchecks Unit 5, Howbury Technology Centre, Thames Road, Kent, DA1 4RQ 01322525180 / 07412103484

What does the ECM test involve? Two swabs are taken – one from the entrance to the vagina and the other from the rectum. The private test packs contain straightforward instructions. GBS carriage can come and go, so the swabs are usually taken between 35-37 weeks of pregnancy – they can be done earlier, but then they may not be as reliable in predicting GBS carriage at delivery. They may be done later, but then there’s an increasing chance that the baby will be born before the test result is available. The swabs are then sent direct to the laboratory (with payment) in the envelope provided as part of the GBS Test Pack. Each of the private laboratories above undertakes to have the results available within three working days of their receiving the swabs and to send out the results on that day to the health professional, with if requested a copy to the pregnant woman. As there is no post on Sundays, it may therefore be preferable to take and send off the swab sample towards the beginning of the week. Because 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.