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Distinguishing between prophylactic and immune anti-D


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We have an obstetric patient who was given 1500 iu of prophylactic anti-D at 28 weeks. 3 days later a sample was tested and found to have a titre of 1/256 v R1R1 red cells and a quantification of 7.6 iu/ml.The referring hospital had no record of an antibody screen result immediately prior to the administration of the prophylaxis though they did have a record of a negative antibody screen in April. The results of the current tests would appear to be a little high if they were due to the prophylaxis, however I have found a report saying that ocassionally levels of 6 iu/ml of anti-D have been detected following standard anti-D prophylaxis. I wondered if anyone had any thoughts about whether our results could be due to the prophylaxis? We will continue test her regularly so that we can monitor the anti-D levels.

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We have an obstetric patient who was given 1500 iu of prophylactic anti-D at 28 weeks. 3 days later a sample was tested and found to have a titre of 1/256 v R1R1 red cells and a quantification of 7.6 iu/ml.The referring hospital had no record of an antibody screen result immediately prior to the administration of the prophylaxis though they did have a record of a negative antibody screen in April. The results of the current tests would appear to be a little high if they were due to the prophylaxis, however I have found a report saying that ocassionally levels of 6 iu/ml of anti-D have been detected following standard anti-D prophylaxis. I wondered if anyone had any thoughts about whether our results could be due to the prophylaxis? We will continue test her regularly so that we can monitor the anti-D levels.

I have ABSOLUTELY NO doubt that this is an immune anti-D, and this lady's blood should be tested every two weeks until delivery as a minimum, that the pregnancy should be monitored by MCA Doppler/ultrasound and that referral to a Specialist Foetal Medicine Unit should be considered, depending upon the results.

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Have to agree with Malcolm definite IMMUNE anti-D , no way would it be 7.6 iu/ml 3 days post injection

we had to test patients bloods at 28 weeks before issuing anti-D, never found a positive screen but we had to do it

Obviously had a sensitising episode since April , you would be surprised how many have falls , bleeding etc and don't report it to midwifes , even had some reported to midwifes who then did not realise mum would need anti-D

also had the Kleihauer was negative did not think she needed anti-D error

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I also would agree with Mr. Needs. I can't remember where I have seen it published but I think the titers from prophylactic ant-D are never more than 1:8 or 1:16. Most we have seen are 1:4. (Depending on the methodology you are using for your titrations.) If you start seeing titers of >/= 1:32 I would be indicating it was an immune anti-D. Definitely monitor this case.

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The highest titer I have ever heard of due to Rhogam was 32. I would let patient's physician know of

the 256 titer. He or she may want to monitor the baby since it is well above the critical titer for Anti-D.

An increase in a repeat titer(not necessary since the titer is critical) would indicate the presence of an

actively acquired Anti-D.

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The problem is that we have all "heard" of high titres and high quantification of anti-D due to anti-D immunoglobulin, but are these incidences apocraphal?

I am not saying that they have not been reported in the literature, but I can say with some certainty that I have never read anything in a peer-reviewed journal that I can recall quoting such a case.

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But seriously, can I ask a dumb question? Why is the Rhogam dose so high? We give 250iu first trimester, 625iu at 28 weeks, then another 625iu post partum if bub is Rh positive. We did have a 600iu dose in there somewhere for quite a while, but it was discontinued because bubs were showing signs of HDN from the prophylaxis. I think. I type this out and have a creepy feeling that I've misread something somewhere.

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But seriously, can I ask a dumb question? Why is the Rhogam dose so high? We give 250iu first trimester, 625iu at 28 weeks, then another 625iu post partum if bub is Rh positive. We did have a 600iu dose in there somewhere for quite a while, but it was discontinued because bubs were showing signs of HDN from the prophylaxis. I think. I type this out and have a creepy feeling that I've misread something somewhere.

lateonenite,I think maybe you misread the previous posts, the idear is immune anti-D, not prophylaxis.

Because D neg is so rare in China, we are not routinely prophylaxis for this condition. I don't know if the Rhogam prophylaxis dose is equal to everyone except the futus bleeding is more than normal, if like this , the puerpera's blood volume is not the same, if the dose is same, then in some low volume puerpera the titier will be higher than others. This is just my guess, if something wrong please point it out, thanks in advance.

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lateonenite,I think maybe you misread the previous posts, the idear is immune anti-D, not prophylaxis.

Because D neg is so rare in China, we are not routinely prophylaxis for this condition. I don't know if the Rhogam prophylaxis dose is equal to everyone except the futus bleeding is more than normal, if like this , the puerpera's blood volume is not the same, if the dose is same, then in some low volume puerpera the titier will be higher than others. This is just my guess, if something wrong please point it out, thanks in advance.

Cheers shily, I was asking a general question about the Rhogam dose rather than this patient - I have the creepy feeling because it's been a long time since I looked at our guidelines in Australia. I had assumed though (bad thing in a blood banker) that anti-D was given at the same or similar dosages everywhere.

Do you mean that in China that prophylaxis is only given in certain cases and tailored to each patient? Thanks,

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With all the abstracts and posters at AABB annual meetings I probably did see something there about the low titers and prenatal RhIg. We report that titers less than 1:8 are consistent with prenatal RhIg but it is up to the clinician to decide the significance since we rarely have the patient's history or clinical data. Any titer result may be important during a pregnancy and should be evaluated on a case by case basis. IgG crosses the placenta at any titer. Also, the clinical significance of the antibody specificity and literature references with regards to HDN are as well important to investigate. Titers are what they are. Given the consequences, any anti-D should be investigated during a pregnancy. This case, again, Mr. Needs said it best, absolutely immune anti-D and monitor it.

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Cheers shily, I was asking a general question about the Rhogam dose rather than this patient - I have the creepy feeling because it's been a long time since I looked at our guidelines in Australia. I had assumed though (bad thing in a blood banker) that anti-D was given at the same or similar dosages everywhere.

Do you mean that in China that prophylaxis is only given in certain cases and tailored to each patient? Thanks,

In China, the D neg is 3 in 1000 person, and once received D pos blood( we will give D neg cells if not in emergency) or D pos pregnency , only 20% will produce anti-D, so the percentage is so rare.

In our hospital , we rarely see one HDFN is due to anti-D.so we will not give Rhgam to gravida except someone buy it from other country.:):):)

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Which method are you using to come up with the titer? When we switched from tube to gel, the titers would differ by up to 4 tubes, so once low titers were suddenly high. I work at an urban hospital which has many women use the ER as a prenatal clinic. They hospital hop and may get several Rhogam injections during their pregnancy. On manual capture, its not unusual to have 4+ Passive Anti D at delivery. We don't titer them.

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But seriously, can I ask a dumb question? Why is the Rhogam dose so high? We give 250iu first trimester, 625iu at 28 weeks, then another 625iu post partum if bub is Rh positive. We did have a 600iu dose in there somewhere for quite a while, but it was discontinued because bubs were showing signs of HDN from the prophylaxis. I think. I type this out and have a creepy feeling that I've misread something somewhere.

In the US we give the RhIgD in 2 doses- 1500IU or 300mcg at the beginning of the third trimester (28 weeks) then at least another 1500IU within 72 hours of the delivery of a Rh-positive fetus, more if warranted by the Coombs and KB testing.

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