Bleeding after strep b test

Strep B Test: MedlinePlus Medical Test

What is a group B strep test?

Strep B, also known as group B strep (GBS), is a type of bacteria commonly found in the digestive tract, urinary tract, and genital area. It rarely causes symptoms or problems in adults but can be deadly to newborns.

In women, GBS is mostly found in the vagina and rectum. So a pregnant woman who is infected can pass the bacteria to her baby during labor and delivery. GBS can cause pneumonia, meningitis, and other serious illnesses in a baby. GBS infections are the leading cause of death and disability in newborns.

A group B strep test checks for GBS bacteria. If the test shows that a pregnant woman has GBS, she can take antibiotics during labor to protect her baby from infection.

Other names: group B streptococcus, group B beta-hemolytic streptococcus, streptococcus agalactiae, beta-hemolytic strep culture

What is it used for?

A group B strep test is most often used to look for GBS bacteria in pregnant women. Most pregnant women are tested as part of routine prenatal screening. It may also be used to test infants who show signs of infection.

Why do I need a group B strep test?

You may need a strep B test if you are pregnant. The American College of Obstetricians and Gynecologists recommends GBS testing for all pregnant women. Testing is usually done in the 36th or 37th week of pregnancy. If you go into labor earlier than 36 weeks, you may be tested at that time.

A baby may need a group B strep test if he or she has symptoms of infection. These include:

• High fever
• Trouble with feeding
• Trouble breathing
• Lack of energy (hard to wake up)

What happens during a group B strep test?

If you are pregnant, your health care provider may order a swab test or a urine test.

For a swab test, you will lie on your back on an exam table. Your health care provider will use a small cotton swab to take a sample of cells and fluids from your vagina and rectum.

For a urine test, you will most likely be told to use the "clean catch method" to ensure your sample is sterile. It includes the following steps.

• Wash your hands.
• Clean your genital area with a cleansing pad given to you by your provider. To clean, open your labia and wipe from front to back.
• Start to urinate into the toilet.
• Move the collection container under your urine stream.
• Collect at least an ounce or two of urine into the container, which should have markings to indicate the amounts.
• Finish urinating into the toilet.
• Return the sample container as instructed by your health care provider.

If your baby needs testing, a provider may do a blood test or a spinal tap.

For a blood test, a health care professional will use a small needle to take a blood sample from your baby's heel. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. Your baby may feel a little sting when the needle goes in or out.

A spinal tap, also known as a lumbar puncture, is a test that collects and looks at spinal fluid, the clear liquid that surrounds the brain and spinal cord. During the procedure:

• A nurse or other health care provider will hold your baby in a curled-up position.
• A health care provider will clean your baby's back and inject an anesthetic into the skin, so your baby won't feel pain during the procedure. The provider may put a numbing cream on your baby's back before this injection.
• The provider may also give your baby a sedative and/or pain reliever to help him or her better tolerate the procedure.
• Once the area on the back is completely numb, your provider will insert a thin, hollow needle between two vertebrae in the lower spine. Vertebrae are the small backbones that make up the spine.
• The provider will withdraw a small amount of cerebrospinal fluid for testing. This will take about five minutes.

Will I need to do anything to prepare for the test?

You don't any special preparations for group B strep tests.

Are there any risks to the test?

There is no risk to you from a swab or urine test. Your baby may have slight pain or bruising after a blood test, but that should go away quickly. Your baby will likely feel some pain after a spinal tap, but that shouldn't last too long. There is also a small risk of infection or bleeding after a spinal tap.

What do the results mean?

If you are pregnant and results show you have GBS bacteria, you will be given antibiotics intravenously (directly to your veins) during labor, at least four hours before delivery. This will prevent you from passing the bacteria to your baby. Taking antibiotics earlier in your pregnancy is not effective, because the bacteria can grow back very quickly. It's also more effective to take antibiotics through your vein, rather than by mouth.

You may not need antibiotics if you are having a planned delivery by Cesarean section (C-section). During a C-section, a baby is delivered through the mother's abdomen rather than vaginally. But you still should be tested during pregnancy because you may go into labor before your scheduled C-section.

If your baby's results show a GBS infection, he or she will be treated with antibiotics. If your provider suspects a GBS infection, he or she may treat your baby before test results are available. This is because GBS can cause serious illness or death.

If you have questions about your results or your baby's results, talk to your health care provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a group B strep test?

Strep B is one type of strep bacteria. Other forms of strep cause different types of infections. These include strep A, which causes strep throat, and streptococcus pneumoniae, which causes the most common type of pneumonia. Streptococcus pneumonia bacteria can also cause infections of the ear, sinuses, and bloodstream.

References

1. ACOG: The American College of Obstetricians and Gynecologists [Internet]. Washington D.C.: American College of Obstetricians and Gynecologists; c2019. Group B Strep and Pregnancy; 2019 Jul [cited 2019 Nov 15]; [about 3 screens]. Available from: https://www.acog.org/Patients/FAQs/Group-B-Strep-and-Pregnancy
2. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Group B Strep (GBS): Prevention; [cited 2019 Nov 15]; [about 4 screens]. Available from: https://www.cdc.gov/groupbstrep/about/prevention.html
3. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Group B Strep (GBS): Signs and Symptoms; [cited 2019 Nov 15]; [about 4 screens]. Available from: https://www.cdc.gov/groupbstrep/about/symptoms.html
4. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Streptococcus Laboratory: Streptococcus pneumoniae; [cited 2019 Nov 15]; [about 3 screens]. Available from: https://www.cdc.gov/streplab/pneumococcus/index.html
5. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Travelers' Health: Pneumococcal Disease; [updated 2014 Aug 5; cited 2019 Nov 15]; [about 3 screens]. Available from: https://wwwnc.cdc.gov/travel/diseases/pneumococcal-disease-streptococcus-pneumoniae
6. Intermountain Healthcare: Primary Children's Hospital [Internet]. Salt Lake City: Intermountain Healthcare; c2019. Lumbar Puncture in a Newborn; [cited 2019 Nov 15]; [about 4 screens]. Available from: https://intermountainhealthcare.org/ext/Dcmnt?ncid=520190573
7. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Blood Culture; [updated 2019 Sep 23; cited 2019 Nov 15]; [about 2 screens]. Available from: https://labtestsonline. org/tests/blood-culture
8. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Prenatal Group B Strep (GBS) Screening; [updated 2019 May 6; cited 2019 Nov 15]; [about 2 screens]. Available from: https://labtestsonline.org/tests/prenatal-group-b-strep-gbs-screening
9. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Urine Culture; [updated 2019 Sep 18; cited 2019 Nov 15]; [about 2 screens]. Available from: https://labtestsonline.org/tests/urine-culture
10. Michigan Medicine: University of Michigan [Internet]. Ann Arbor (MI): Regents of the University of Michigan; c1995–2021. Group B Streptococcal Infections in Newborns[cited 2021 Aug 6]; [about 3 screens]. Available from: https://www.uofmhealth.org/health-library/zp3014spec
11. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2019. Health Encyclopedia: Group B Streptococcus Infection in Babies; [cited 2019 Nov 15]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=90&contentid=P02363
12. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2019. Health Encyclopedia: Pneumonia; [cited 2019 Nov 15]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=85&contentid=P01321
13. WHO Guidelines on Drawing Blood: Best Practices in Phlebotomy [Internet]. Geneva (SUI): World Health Organization; c2010. 6. Paediatric and neonatal blood sampling; [cited 2019 Nov 15]; [about 3 screens]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK138647

Group B strep test | Pregnancy Birth and Baby

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If you’re pregnant, one of the routine antenatal tests you’ll probably have is for group B streptococcus (also known as ‘group B strep’ or ‘GBS’). This page explains what the test is for, which babies are at risk of infection and how group B strep is treated.

What is group B strep?

Group B strep is a type of bacteria commonly found in the intestines, rectum, urethra or vagina. Many women have it, and it usually causes no health concerns or symptoms. Some women infected with group B strep get a urinary tract infection, and it increases the risk of a miscarriage only very slightly.

The main concern is passing it on to the baby before or during a vaginal birth. While many babies who get infected stay healthy, a small proportion (about 1 in 200) become very sick within the first few days of life. They get serious infections such as pneumonia and blood poisoning, or meningitis, which is an infection around the brain.

These seriously ill babies are treated with intravenous antibiotics. Most recover with no side-effects, but some don't survive.

Group B strep test

The group B strep test is a routine antenatal test. It involves taking a swab of the inside of the vagina. Your doctor or midwife will do this, or you may be able to do it yourself. The swab is taken at 35 to 37 weeks' pregnancy. Tests done earlier in your pregnancy aren't a good guide to your condition at birth because the bacteria can come and go.

Who has the group B strep test?

Some hospital and doctors recommend that every pregnant woman has a group B strep test.

But others ask only some women to have the test if they are at higher-than-average risk because they go into labour early, or their waters break early.

Even if you're planning a caesarean, you can think about having the test in case your waters break early or you go into labour unexpectedly early.

Talk about the risks and benefits of the group B strep test with your midwife or doctor.

Risk factors for infection with group B strep

Babies are more likely to be infected with group B strep if:

• they are born, or your waters break, before 37 weeks
• you give birth more than 18 hours after your waters break
• you have a fever (over 38°C) while in labour
• you've had a previous child with severe group B strep infection
• a urine test during pregnancy detected group B strep
• a swab taken no more than 5 weeks earlier detected group B strep

Preventing group B strep from infecting your baby

If your group B test at 35 to 37 weeks was positive, or if you have the risk factors listed above, your doctor or midwife will probably recommend that you have intravenous antibiotics when your waters break or labour starts.

Often this is penicillin, but alternatives are available if you are allergic to penicillin. The antibiotics pass through the placenta and into the baby. This greatly reduces your baby's chances of becoming ill.

There's no need for antibiotics before a planned caesarean because the baby will not pass through the vagina. You can't pass the bacteria to your baby through the placenta.

After the birth

If you had antibiotics during labour, your baby will be monitored for the first couple of days for signs of infection. The chance of your baby being infected is low.

Late-onset group B strep

There is a very small group of babies that develop group B strep infection weeks or months after birth (called ‘late onset group B strep'). They become seriously ill quite quickly, with fevers and vomiting and difficulty feeding. Unfortunately, the group B strep test and use of antibiotics doesn’t prevent a baby developing late-onset group B strep infection.

If your child's condition deteriorates quickly, call triple zero (000) and ask for an ambulance, or go to the nearest hospital emergency department.

When to seek help

If you want more information about group B strep, or if you have any concerns about your baby, call Pregnancy, Birth and Baby on 1800 882 436 to speak to a maternal child health nurse, or talk to your midwife or doctor.

Sources:

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: May 2020

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• Pregnancy checkups, screenings and scans

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