GBS in your urine means that you may be heavily colonized which puts your baby at greater risk. So how do you know if you have GBS in your urine, and what should you do?
Your provider should do a urine culture for GBS and other bacteria (this is not the standard prenatal urine “dipstick” check) at the first prenatal visit. What is the difference between a dipstick test and a GBS urine test?
A dipstick test: It is a test where a plastic strip is dipped into urine. The plastic strip is treated with chemicals that will react and change colors depending on levels in the urine. This test does not react to GBS levels. It can react to pH, protein, glucose, white blood cells, bilirubin, and blood. This test does not react to GBS levels.
A GBS urine test: GBS urine test is a culture. In a urine culture is a test to find germs in the urine can can cause an infection, since the urine in the bladder is typically sterile. Bacteria may enter the urethra and cause infection. The test is completed by adding urine to a substance that promotes the growth of germs. A sample of urine is added to a substance that promotes the growth of germs. If no germs grow, the culture is negative. If germs grow, the culture is positive. The type of germ may be identified using a microscope or chemical tests.
Be sure to ask for the results of your urine culture
It is now the standard of care in several countries for all pregnant women to be routinely tested for GBS at 35–37 weeks during each pregnancy unless their urine already cultured positive in the current pregnancy. (Since levels of GBS can change, each pregnancy can be different.)
If your urine tests negative, then there is not GBS in your urine. It is important to note women may still carry GBS in their vagina and/or rectum, even if it is not present in their urine. Therefore, women should still receive a GBS swab test at 35-37 weeks.
GBS in your urine means that you may be heavily colonized which puts your baby at greater risk.If you have a significant level of GBS in your urine, your provider should prescribe oral antibiotics at the time of diagnosis. GBSI advocates a recheck (“test of cure”) one month after treatment. If your urine tests positive, your provider should consider you as “GBS colonized” for this pregnancy so that you receive IV antibiotics for GBS when labor starts or your water breaks. Please note that once you have tested positive in your urine during this pregnancy, your provider will likely not do a routine vaginal/rectal swab test for you later in this pregnancy since you should already be considered "GBS colonized."
According to the CDC, "if a urine culture is reported as positive for GBS, that woman should be considered GBS positive. While guidelines now require that labs only report relatively high (i.e., 104 colony forming units/mL) colony counts of GBS in urine cultures, we recommend that providers manage all GBS positive urine cultures equally, regardless of colony count, and consider any woman with a urine culture positive for GBS to be GBS positive for that pregnancy."
If a women's urine culture tests positive for GBS early in pregnancy, she's treated, and following urine culture are negative, she still requires IV antibiotics during labor. The CDC notes that "studies have shown that GBS bacteriuria is a sign of heavy GBS colonization, which may not be entirely eradicated with treatment. GBS bacteriuria is a risk factor for having an infant with early-onset GBS disease. This patient should thus receive intrapartum antibiotic prophylaxis, and does not require screening for GBS at 35-37 weeks because regardless of that screening result she will require intrapartum antibiotic prophylaxis."
If you have already had a baby who was infected with GBS disease or have had GBS in your urine in this pregnancy, you should receive IV antibiotics for GBS during labor and delivery even if you later test negative for GBS in your urine or in a vaginal/rectal swab test for GBS in this pregnancy.
If you have not had a baby with GBS disease, you should ask to have your urine cultured for GBS early in this pregnancy (not standard in all countries) and also to have a vaginal/rectal swab test for GBS between 35-37 weeks gestation (also not standard in all countries) regardless of any past pregnancy results for GBS.
If you have not had a baby with GBS disease and have tested positive or negative in the past, you should ask to have your urine cultured and to have a GBS swab test between 35-37 weeks.
What to do When Your Water Breaks Or Labor Starts
Call your care provider. Report any fever. Remind him or her of your GBS status. If you have already had a baby with GBS disease or have had GBS in your urine in this pregnancy, you should receive IV antibiotics regardless of this pregnancy’s GBS test results.