GBS unkown status prophylaxis

[lordman]

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pre-term labor ( < 37 weeks) is one of the indications of prophylaxis in GBS unknown status. However, what is the case if the pregnant is at term (e.g., 39 weeks), and GBS status is unknown? Why it is not indicated here? Shouldn't the risk be the same here as well?

@ChessMaster3000 @Phloston

 

[ChessMaster3000]

pre-term labor ( < 37 weeks) is one of the indications of prophylaxis in GBS unknown status. However, what is the case if the pregnant is at term (e.g., 39 weeks), and GBS status is unknown? Why it is not indicated here? Shouldn't the risk be the same here as well?

@ChessMaster3000 @Phloston

I do believe the risk is less. Whether that less risk still warrants prophylaxis is in fact your question, and I'm sorry, I am not sure. I hate these GBS prophy rules, they get so specific.

 

[Phloston]

pre-term labor ( < 37 weeks) is one of the indications of prophylaxis in GBS unknown status. However, what is the case if the pregnant is at term (e.g., 39 weeks), and GBS status is unknown? Why it is not indicated here? Shouldn't the risk be the same here as well?

@ChessMaster3000 @Phloston

When to give GBS prophylaxis:

- Hx of prior pregnancy resulting in neonate with GBS (i.e., prior GBS+ pregnancy without neonatal disease doesn't count here)
- GBS bacteriuria in current pregnancy
- Positive vaginal or rectal culture (you screen all pregnant women at 35-37 weeks gestation except for women who fit the above two criteria because of the obviation)

If you don't know the culture results or they were not performed, any of the following warrants prophylaxis. This is because if culture results are not known, then precautionary measures are appropriate if a GBS propensity variable is present:

Intrapartum fever (>38)
Preterm status (<37 wks)
Prolonged rupture of membranes (>18 hrs)
Positive intrapartum nucleic acid amplification test (NAAT)

When not to give GBS prophylaxis:

- As talked about above, if a mom had a prior GBS+ pregnancy that did not result in neonatal disease, you don't give prophylaxis
- Planned C-section, even if the mom is GBS+. Notice that the moms are still screened at 35-37 wks though because it's always possible that preterm labor or premature rupture of membranes could occur
- Women with negative GBS cultures, even if they have fever, are preterm, have prolonged rupture of membranes. If you suspected chorioamnionitis though, you'd still Tx for that (ampicillin + gentamicin +/- clindamycin; bear in mind that endometritis you just give clindamycin + gentamicin, OR ampicillin-sulbactam).

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All of that info is from UpToDate btw.

http://www.uptodate.com/contents/neonatal-group-b-streptococcal-disease-prevention?source=machineLearning&search=group b strep prophylaxis&selectedTitle=1~120&sectionRank=1&anchor=H8#H8

http://www.uptodate.com/contents/postpartum-endometritis?source=machineLearning&search=endometritis treatment&selectedTitle=1~106&sectionRank=2&anchor=H22#H22

http://www.uptodate.com/contents/intraamniotic-infection-chorioamnionitis?source=machineLearning&search=chorioamnionitis treatment&selectedTitle=1~118&sectionRank=2&anchor=H21#H21

 

[notbobtrustme]

I do believe the risk is less. Whether that less risk still warrants prophylaxis is in fact your question, and I'm sorry, I am not sure. I hate these GBS prophy rules, they get so specific.

Where I did my rotation, if GBS status was unknown -> automatic prophylaxis.

These guidelines are ******ed and take clinical decision making out of the loop. They also require way too much time, energy and resources to go through.

 

[Phloston]

Where I did my rotation, if GBS status was unknown -> automatic prophylaxis.

These guidelines are ******ed and take clinical decision making out of the loop. They also require way too much time, energy and resources to go through.

I think they're in place to let you know when prophylaxis should be considered mandatory. The vast majority of 40-wk women with unknown status are actually negative so the prophylaxis becomes an extra cost.

 

[notbobtrustme]

I think they're in place to let you know when prophylaxis should be considered mandatory. The vast majority of 40-wk women with unknown status are actually negative so the prophylaxis becomes an extra cost.

ya until that one case of GBS sepsis comes back and costs the system 20 million dollars. Then all those cheap bags of penicillin don't look all that expensive, even for negative carriers.

 

[Akr]

I've just been reviewing this stuff too so let me have a stab (and please do correct me if I'm wrong!):

Risks of transmission to baby from GBS-unknown mother are the same at any gestational age. BUT babies' death rates from invasive GBS are much higher if they're preterm (like 22% vs. 2%). So the benefits of abx outweigh risks for the preterm cases, and justify ppx without testing.

If we're managing GBS-unknown labor at term, with no risk factors as mentioned above:

-one option is to get a rapid GBS test if available and treat accordingly, just as if it were a screening culture result (fyi the universal screening swab we're supposed to do at 35-37wk has at least 4% false positive rate).

-if rapid GBS test isn't available, then DON'T prophylax the GBS-unknown lady with no risk factors! The risks (and associated costs) in that case outweigh the benefits. Benefits being prevention of the 2% death rate from invasive GBS IF she is colonized AND transmits it. The main risks here include development of antibiotic-resistant sepsis, which now rivals or supercedes GBS sepsis in neonatal morbidity/mortality, and also maternal anaphylaxis to the antibiotic.

This is all coming from a pretty well-cited review that my Ob/Gyn advisor put together for us; hopefully it makes sense! If not I'd be happy to try & clarify