Some individuals are advised to have testing for Group B Strep (GBS) in their current pregnancy between 35-37 weeks:
- You were identified to have had a positive GBS result in a previous pregnancy
- A previous baby was diagnosed and treated for GBS Positive result
- GBS was identified by chance earlier in your pregnancy either in your urine or from a swab and you are being offered a repeat test
A Brief Summary of What is GBS and Why test for it?
Group B Streptococcus (GBS) is normally a harmless and common bacteria which may be identified in your urine or from a vaginal and/or rectal swab, it effects 2–4 in 10 women (20–40%) in the UK and usually causes no harm to that individual, there are no symptoms and it is not a sexually transmitted infection.
Whilst carrying GBS is usually harmless pre-pregnancy or during pregnancy, it may affect your baby around the time of birth. Whilst most babies are born safely and will not develop GBS, occasionally it can cause serious infection in newborn babies.
When and how do you test for GBS?
Routine testing of all pregnant individuals is not generally recommended in the UK as GBS is a transient organism (can come and go), screening is currently based upon risk factors as stated above.
Where individuals choose to undertake the test, this is normally recommended between 35-37 weeks gestation (32-34 weeks for twins). The test involves taking a swab from both the lower vaginal and anal/rectal areas (see below), and this test will tell you if GBS bacteria is currently present at that time of testing.
For more information about available self-testing, not through the NHS, visit the Group B Strep Support (GBSS) website: www.gbss.org.uk/TestingforGBS
Sometime GBS can be detected by chance in a urine sample, when a healthcare professional sends a sample off for screening for a suspected urinary tract infection. If this is detected in your urine, oral antibiotics will be advised and you will be offered intravenous (IV) prophylactic antibiotics in labour.
Instructions for the collection of a low vaginal and anorectal swab for the detection of Group B Streptococcus (GBS)
You will have been provided with a swab to undertake self-testing procedure to determine if you have a current presence of the group B Streptococcus (GBS) bacterium present within your vagina or bowel. Please read all instructions before collecting specimens. If you have any questions about this procedure, please ask your midwife or doctor.
- Wash hands with soap and water, rinse and dry.
- Unpack the kit on a clean surface, ideally near a toilet and remove underwear.
- It is important to maintain a comfortable balance during the collection procedure.
- Twist the cap to break the seal of the swab. Pull the cap with attached swab off the tube. Do not touch the soft tip or lay the swab down. If you touch or drop the swab tip or the swab is laid down, discard and request a new vaginal swab from your midwife.
- Hold the swab by the cap with one hand so the swab is pointing toward you.
- With your other hand, gently spread the skin of the labia. Insert the tip of the swab into the vaginal opening. Point the tip toward your lower back and relax your muscles.
- Gently slide the swab around 2cm into the vagina. If the swab does not slide easily, gently rotate the swab as you push. If it is still difficult, do not attempt to continue and seek advice from your midwife.
- Make sure the swab touches the inside walls of the vagina so that moisture is absorbed.
- Rotate the swab for 10-15 seconds around the front, sides and back of the vagina and then withdraw the swab.
- Insert the same swab gently into the anus so that around 1cm of the swab is within the rectum.
- Rotate the swab for 10-15 seconds and then withdraw the swab.
- Return the swab to the tube and cap securely.
- After collection, wash hands with soap and water, rinse and dry.
- Apply a patient ID label from the request from to the side of the tube and seal within a transport bag. Return the sample with the request form to your midwife or doctor.
How to store the sample if done at home and not in the hospital or during a community midwife appointment.
Ideally, you should deliver the sample to Antenatal Clinic reception, MAC or Delivery Suite as soon as possible after the sample has been taken. If you cannot deliver the sample immediately it should be stored in a fridge at around 4°C, but for no longer than 24 hours. Place the sample in an extra plastic bag before putting it in the fridge.
What happens next?
The sample will be tested at the pathology department at Harrogate District Hospital. Your results will normally be reported within 72 hours after the pathology department has received your sample.
Results will be checked by your midwife or doctor and we will contact you if the test results suggest further action is needed. Normally, no treatment will be required until presenting in labour. If you have been informed of a GBS positive result, it is important that you make staff aware of this when contacting the maternity unit, if your waters break, if you feel unwell or when presenting in labour.
What happens to my sample after it has been tested?
Once your sample has been tested and a result has been sent back to your referring doctor or midwife, the remaining sample will be disposed of with the other laboratory waste.
What does the test result mean?
If your result is GBS Negative
This means that the test has not managed to isolate the organism and it is likely that you do not currently have GBS within your vagina or bowel. No further action is required and there should be no change to your labour management.
If your result is GBS Positive
This means that GBS has been found within your vagina or bowel. There is a small chance of this being passed to your baby during the birth, and you are recommended to have antibiotics in labour to reduce the risk of transmission.
Antibiotics reduce the risk of your baby developing a GBS infection in their first week of life from around 1 in 400 to 1 in 4000. Ideally antibiotics (penicillin, or suitable alternative if you are allergic) should be given at least 4 hours before your baby is born and would normally be administered intravenously through a cannula in your hand every 4 hours throughout labour. In addition:
- if your waters break (membranes rupture) prior to spontaneous labour you will be advised to have labour induced (artificially started) as soon as possible, as this is when the baby is at most risk of developing infection. Ask for our ‘Induction of Labour’ leaflet for more information.
- you are still eligible to use the bath for labour and birth (unless you have other risk factors or need a hormone drip as part of the induction process)
- your baby will be closely monitored for signs of infection after birth
If your waters break preterm (before 37 weeks) but you are not in labour, you may be offered a course of oral antibiotics. See the National Institute of Health and Care Excellence (NICE) guidance NG25 on Preterm Labour and Birth: www.nice.org.uk/guidance/ng25/chapter/Recommendations#antenatal-prophylacticantibiotics-for-women-with-p-prom
For more in-depth information regarding GBS please see ‘Group B Streptococcus in Pregnancy and Newborn Babies’ leaflet (RCOG, https://www.rcog.org.uk/for-the-public/ to read in addition to this page.
References
Group B Streptococcal Disease, Early Onset (Green Top Guideline No.36). https://www.rcog.org.uk
Group B Streptococcus (GBS) in pregnancy and newborn babies. Information leaflet. https://www.rcog.org.uk/for-the-public/
Group B Strep Support (GBSS) website: www.gbss.org.uk/TestingforGBS
National Institute of Health and Care Excellence (NICE) guidance NG25 on Preterm Labour and Birth: www.nice.org.uk/guidance/ng25/chapter/Recommendations#antenatal-prophylacticantibiotics-for-women-with-p-prom