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Ortho Fetal Screen kit


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Ortho Fetal Screen kit can be used to detect the status of fetal cells (Rh +) circulating in mom’s body to decide if one dose RhoIg is sufficient or not for post-delivery mom(Rh-, no known allo anti-D).

 

Some hospitals use this kit exclusively for the post-delivery mom, but some hospitals also use it for the pregnant patients with spotty bleeding or trauma/fall/car accident at the emergency department. In the latter case, the fetus Rh is unknown.

 

If you read Orth insert, it only mentions that this screen kid valid for the postpartum  sample with known Rh status of newborn (Rh +) and mom (Rh-). So that means the hospitals cannot use it to screen antepartum hemorrhage samples on RH- patient? If not, how can we know, with confident,  that one shot RhoIg sufficient for these antepartum patients with bleeding or trauma? Even though we may think about Kleihauer–Betke test, but it did not tell you the circulating fetal cells, if K-B test positive, are Rh + or -. 

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I don't think there is differ between postpartum bleeding and post trama/fall/car accident bleeding except the latter we don't know the RhD status of the baby, but if it is pos, we can use it for sure, if the D is neg of the baby, the Feta Screen result is neg of course, there is no influence the RhoIg injection.

Just personal idea, I hope my expression is clear. :P :P :P

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I don't think there is differ between postpartum bleeding and post trama/fall/car accident bleeding except the latter we don't know the RhD status of the baby, but if it is pos, we can use it for sure, if the D is neg of the baby, the Feta Screen result is neg of course, there is no influence the RhoIg injection.

Just personal idea, I hope my expression is clear. :P :P :P

 

I agreed. But I did not understand why Ortho in its insert only limits its use for the postpartum. 

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My understanding of the fetal screen kit is that it will only give you a qualitative result.  You would need to do a KB stain to determine how many vials of Rhogam are required.  That being said, we haven't used the fetal screen kit in many years so if it has changed please ignore me ;)    In any case we would use the KB stain for suspected antenatal fetal/maternal bleeding because we do not know the blood type of the baby and I have even seen them order it on Rh+ moms (again...that was years ago) 

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You cannot be sure the 1 vial of Rh Immune globulin is sufficient unless a KB or Flow cytometry is performed to calculate the percentage of fetal cells in maternal circulation.

The principle of the Ortho Fetal Screen is to determine the circulating Rh+ cells (not fetal cells), which is why it is necessary to only perform on post delivery Rh negative mothers who give birth to Rh positive infants.  

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It is my understanding that KB test alone can only tell you if there are fetal cells circulating in the mom and the percentage. It does not tell these circulating fetal cells are Rh- or Rh+. If fetal is Rh-, no matter how many fetal cells circulating, the mom is not indicated for RhoIg. Therefore, KB test itself almost has no role to play in administration of RhoIg, assuming fetal Rh status is unknown. Some may argue that, considering almost 85% population is Rh pos, even though fetal Rh unknown, it may be statistically safe to assume the fetal is Rh+ and just give the RhoIg based on the KB result. Well, it is really a hard sell, especially when there is alternative way to proceed. 

 

I will say, in the case of fetal Rh unknown, especially for prenatal mom at ER, first we do fetal screen. If neg, at least you are sure that, regardless the fetal Rh+or -, one shot is enough. if fetal screen is pos, you will automatically give one shot first, then rely on the KB result to determine how many extra shots to give with confidence, because you know the fetal is Rh+ based on post fetal screen result. The positive  fetal screen tells you the fetal is Rh+, for sure, assuming mom DAT is negative (otherwise may cause false pos fetal screen). Therefore I recommend the combination of fetal screen and KB test. Whether to do KB test depends on the fetal screen result first. 

 

I still do not understand what is the reason to let Ortho limit fetal screen kit in the postpartum with known Rh of newborn (Rh+, based on Cord or heelstick grouping test)and the mom (Rh-) in its product insert. 

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I think the Ortho limits are due to the fact that there are very few antenatal fetal bleeds that would be detected by the screening assay.  Most of the time the docs are looking at some abdominal trauma and want to determine if the placental circulation has been compromised - hence the use of the KB stain, looking for fetal cells, not Rh+ ones.

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Ortho Fetal Screen kit can be used to detect the status of fetal cells (Rh +) circulating in mom’s body to decide if one dose RhoIg is sufficient or not for post-delivery mom(Rh-, no known allo anti-D).

 

Some hospitals use this kit exclusively for the post-delivery mom, but some hospitals also use it for the pregnant patients with spotty bleeding or trauma/fall/car accident at the emergency department. In the latter case, the fetus Rh is unknown.

 

If you read Orth insert, it only mentions that this screen kid valid for the postpartum  sample with known Rh status of newborn (Rh +) and mom (Rh-). So that means the hospitals cannot use it to screen antepartum hemorrhage samples on RH- patient? If not, how can we know, with confident,  that one shot RhoIg sufficient for these antepartum patients with bleeding or trauma? Even though we may think about Kleihauer–Betke test, but it did not tell you the circulating fetal cells, if K-B test positive, are Rh + or -. 

Blood Banks should not be using Fetal Screen on any sample except post delivery per the manufacturer's insert.   We learned that the first day of med tech school.  If I inspected a blood bank and they used Fetal Screen on any samples other than post delivery I would give them a deficiency.  

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Blood Banks should not be using Fetal Screen on any sample except post delivery per the manufacturer's insert.   We learned that the first day of med tech school.  If I inspected a blood bank and they used Fetal Screen on any samples other than post delivery I would give them a deficiency.  

Kind of harsh don't you think . . . I use many of my reagents "off label" based on studies I have read in the technical journals AND after validating that they are working the way I anticipated.  If your inspection showed no "reasonable" validation/justification for antenatal testing I might agree.  Rather, as an inspector I feel the most important thing I bring to the table is education.  I would not cite but rather delve into the "why's" of such a practice and then explain why I felt that they were generating data that provided no useful information and was wasting resources; followed by a strong recommendation to cease.   Of course this is only my take on the topic.

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No I don't think it is harsh.   I often wonder about hospitals validating reagents/tests off label becuase I don't think they even come close to the numbers/types of specimens that the manufacturer uses to validate and submit to FDA.  This is just my opinion.   I caution anyone using reagents for purposes other than those intended by the manufacturer. 

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As David said, the KB can be used to evaluate placental circulation. In some cases the physician is ordering it to evaluate the wellbeing of the fetus or to determine/rule out the cause of fetal demise. It may not be used only for determining whether or not mom needs RhoGAM. If testing is requested for determination of fetal wellbeing, the fetal bleed screen is not going to provide the desired information because it is qualitative and, more importantly, it only detects Rh positive fetal cells.

Edited by AMcCord
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No I don't think it is harsh.   I often wonder about hospitals validating reagents/tests off label becuase I don't think they even come close to the numbers/types of specimens that the manufacturer uses to validate and submit to FDA.  This is just my opinion.   I caution anyone using reagents for purposes other than those intended by the manufacturer. 

 

I agree with you. As I said on the Ortho QC thread, any deviation from the manufacturers instructions and the manufqacturers will wipe their hands of you if there is a problem.

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The presence of ABO incompatibility between mother and fetus may result in a false-negative test result. If ABO 

incompatible fetal cells are cleared from the maternal circulation at an accelerated rate, the presence of a large 

feto-maternal hemorrhage may be obscured.

 

From Package insert. Does any one have different SOP based on this limitation?

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The presence of ABO incompatibility between mother and fetus may result in a false-negative test result. If ABO 
incompatible fetal cells are cleared from the maternal circulation at an accelerated rate, the presence of a large 
feto-maternal hemorrhage may be obscured.
 
From Package insert. Does any one have different SOP based on this limitation?

 

 

Our procedure says that the post-delivery specimen should be drawn within 1 hour of delivery, if at all possible. Of course, when the OB department doesn't let you know you have a cord blood specimen for 2-6 hours after delivery, you don't meet that goal very well.

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The presence of ABO incompatibility between mother and fetus may result in a false-negative test result. If ABO 
incompatible fetal cells are cleared from the maternal circulation at an accelerated rate, the presence of a large 
feto-maternal hemorrhage may be obscured.
 
From Package insert. Does any one have different SOP based on this limitation?

 

I would think the KB would have the same limitation. 

 

JB

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In both cases, as far as I am aware, a large FMH would only be obscured if the maternal ABO antibodies had removed the foetal red cells, rather in the same way that the passive anti-D would remove the foetal red cells, and so the obscuring of the large FMH would make no difference?  It is known that a major ABO incompatibility between a D Negative mother and a D Positive foetus can, to a certain extent, mitigate against the mother producing an immune anti-D (see several editions of Mollison's Blood Transfusion in Clinical Medicine).

Edited by Malcolm Needs
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  • 3 months later...

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