Can a group B Strep test be wrong?

Two in five women carry group B Strep. While carriers exhibit no symptoms, it can be harmful to newborn babies.

If you’re pregnant, you may have taken a test. If you have found out since the birth of your baby that you were infected, but tested negative, you may be wondering why this wasn’t picked up, and if someone is to blame.

Belly of a pregnant woman who will need to test for group B strep

What is group B Strep?

Group B Streptococcus (GBS) is an infection caused by the bacterium streptococcus agalactiae. The bacteria are common and tend to be present in the rectal or vaginal regions of the body.

The bacteria are usually harmless in healthy adults, but can occasionally cause harm to a newborn baby. They can also be harmful to the elderly.

Will I be tested for group B Strep if I am pregnant?

As group B Strep is symptomless, the only way to find out if you have it is by doing a test.

The infection is not routinely tested for during pregnancy, although it is sometimes identified during other routine tests.

Group B Strep tests may occasionally be carried out by the NHS. However, you may have to test privately or use a DIY test kit.

Different types of group B Strep tests

There are two broad types of tests:

  • a standard ‘non-selective’ swab test, known as a high vaginal swab (HVS)
  • a group B Strep-specific swab test, known as an enriched culture medium (ECM)

HVS testing

HVS tests are general purpose and not specifically designed to detect group B Strep bacteria. They are usually used to investigate other symptoms.

If you get a positive result using this type of test it is likely to be correct. However, it does not always pick up group B Strep.

Lab technician examining group B strep bacteria under microscope

ECM testing

An ECM test is specifically designed to detect group B Strep. It is available privately, can be bought online and is reliable.

Other types of group B Strep testing

Urine tests

These are often carried out after a dipstick-style test has been done to investigate other symptoms.

A subsequent urine test may detect an infection, but caution is required: a negative urine test only means that bacteria were not found in the urine. It does not mean the bacteria were not present in the vagina or rectum.  

Rapid or ‘bedside’ tests

These require samples from both the low vagina and rectum using a swab. However, there is limited research on just how reliable they are.

What can you do about an incorrect group B Strep test?

If your baby has not yet been born but you have concerns about an incorrect test, speak to your midwife.

In most cases, group B Strep will not affect your baby. However, there will be a small proportion of cases in which it may pose a risk to your baby’s health and wellbeing.

Your midwife may:

  • arrange for you to be tested again
  • recommend giving birth in hospital
  • arrange for you to be given antibiotics during labour.

Alternatively, you could carry out a private test to ensure the first one was accurate.

Pregnant woman discussing group B Strep concerns with midwife

Discovering incorrect test results after giving birth

In some cases, undiagnosed or treated group B Strep can cause an infection in newborn babies, such as meningitis, sepsis, or pneumonia.

If this happens after you’ve had a negative test result, you will undoubtedly want to know why and what went wrong.

There are various situations that may give rise to this situation. It could be that:

  • the test result was incorrect, for one of the above reason
  • you were not tested when you should have been
  • treatment provided after a positive test was not appropriate

The fact your test was wrong does not necessarily mean you received inadequate care or that medical negligence occurred.

However, you may be able to bring a claim if it emerges you were GBS positive and:

  • no additional treatment was recommended
  • no advice was provided
  • poor care was received
  • treatment was delayed

If you believe you have a compensation claim to bring owing to misdiagnosis, poor care or other forms of negligence, our team can help.

At Devonshires Claims, our experienced solicitors can apply their professional expertise to assessing your case and filing a claim for you, on a no win, no fee basis.

For a confidential discussion and free case evaluation, get in touch with the team today.

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