non step 1.. RHOgam

[Conjuctiva]

i'm a bit confused.. i know why they give it, etc, but FA asked what Ig class it was, as it was getting administered to a primigravid 20 weeks along.

i knew it was igG, but i put igM but it was wrong (igG correct).

my reasoning was that igG crosses placenta, thus would bind fetal cells and kill it in utero.. obviously i'm wrong.. so how does that not happen?

i thought RHOgam was given after birth?

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[vkhullar]

i'm a bit confused.. i know why they give it, etc, but FA asked what Ig class it was, as it was getting administered to a primigravid 20 weeks along.

i knew it was igG, but i put igM but it was wrong (igG correct).

my reasoning was that igG crosses placenta, thus would bind fetal cells and kill it in utero.. obviously i'm wrong.. so how does that not happen?

i thought RHOgam was given after birth?

WHat is the page number in FA.

 

[knuckles]

if you do a search there have been plenty of threads discussing this.

 

[Conjuctiva]

sorry, i meant UW

 

[turkeyjerky]

different people say different things. (a pharm professor 2nd year told us it was "heat treated" and thus couldn't cross the placenta, whatever the hell that means.) a more reasonable answer to this question, which was specifically asked and answered by our obgyn course director a few days ago, is that Rhogam is given as an IM dose and is slowly eluded into the bloodstream over the next 8 weeks or so. Only a small amount is present in the blood stream and only a small amount is available to cross into the placenta at any given moment. Thus, some Rhogam can cross into the baby, and may be responsible for a positive direct coomb's test on a neonate, but it will not cause hydrops.

 

[drizzt3117]

The quick answer to this is that the dose isn't really big so even though it can cross the placenta, it doesn't do much. If you read the literature on Rhogam, it says that 300 mcg IM is enough to protect against 15 mL of fetal blood. How much fetal blood is there in a baby? It's a hell of a lot more than 15 mL. So even if that entire 300 mcg crossed the placenta, it wouldn't do enough damage to hurt the baby. Sensitization means your plasma cells make LOTS of anti-D antibodies, and can keep making them, that's the difference.