Anti-D due to antepartum RHIG

[DANDERS]

I am new to gel and can't get over the number of Anti-Ds we are working up on our moms. What protocols are being used to report these out? Do I need to titer each of these or sent it out for IgM/IgG determination? Is there anything to support a "negative screen at 28wks, RHIG given within last 3 mon and 1-2+ reactions" concludes "Anti-D most probably due to antepartum RHIG"?

Any responses would be most appreciated!

Debbie

[johna]

I am new to gel and can't get over the number of Anti-Ds we are working up on our moms. What protocols are being used to report these out? Do I need to titer each of these or sent it out for IgM/IgG determination? Is there anything to support a "negative screen at 28wks, RHIG given within last 3 mon and 1-2+ reactions" concludes "Anti-D most probably due to antepartum RHIG"?

Any responses would be most appreciated!

Debbie

Debbie,

I'm coming from a large reference lab perspective and was formerly employed as a tech rep for one of the RhIg manufacturers.

We are using solid-phase for antibody screening and encounter much the same problem that you are with post-RhIg anti-D. Since we do not have the luxury of having patient history readily available, we are simply reporting the antibodies as is, without any commentary. The docs and nurses should be aware that an antepartum RhIg injection will often result in a positive antibody screen prior to delivery. IgM/IgG determination would be of no practical use since most actively-produced anti-Ds by far would be IgG in nature, as would the antibody in the injection.

We titer all anti-Ds since the rule of thumb is that the titer of a post-RhIg antibody should never exceed 4. If the titer is 128, it's not due to the injection. As far as a "negative screen at 28 weeks" being a baseline to suggest that an anti-D post-RhIg is due only to the injection, you can suggest that but you certainly can't rule out the fact that the patient may have developed her own anti-D at some point after the antepartum RhIg was given. Hope this helps!

[John C. Staley]

Couple of suggetions. If you have a history of a negative antibody screen at 28 weeks don't do an antibody screen at delivery. Just confirm the Rh and give the RhIG. If you are compelled to do an antibody screen and discover an anti-D with a record of antenatal RhIG injection then report something to the effect of "Anti-D possibly due to RhIG". Let the physician decide if you need to do any more.

[Gloria]

If we identify and anti-D in a mom and we are able to verify that she received RhIG recently, we report out the results as : "Anti-D probably due to RhIG received on xxxx(date)"

[Melanie]

We also get a tremendous amount of "passive Anti-D's due to Rhogam given". When the screen comes up pos, we do what we call a "mini-D ruleout panel" in PEG. If only the D+ cell reacts and we have the information concerning when the patient received Rhogam, we call it a "passive Anti-D due to Rh immune globulin received". We do not do titers.

[cell1]

We do a "mini" panel to rule out other antibodies when we detect antepartum RhIg on antibody screens. If it is negative and we have confirmed the injection of RhIg, we report "Anti D detected. RhIg given on XXX date. We make no suggestion as to whether it is "due to the injection". We let the clinician make that decision.

[John C. Staley]

Just an FYI, I had an OB doc come unglued when we reported "Anti-D due to RhIG". Their contention was that we could not know that and had no business reporting it that way. Consequently we chose the waffle language of "Anti-D possibly due to RhIG" and let the doc decide what to do from there.

[Cathy]

We also report out "anti-D, probably due to RhIG injection given on (date)". We also report it as a comment instead of giving the patient an anti-D in history.

[jasonviau]

We also report out "Anti-D due to RhoGAM". The problem we're now trying to deal with is whether to report the antibody screen as positive or negative. We use electronic crossmatch, so our computer system is now prohibiting us from using this function with any patient who has ever had a passive Anti-D. I suppose anyone using Immediate Spin crossmatch would be in the same boat. Has anyone else dealt with this successfully?

[John C. Staley]

I don't know if you would say we have delt with this successfully or not but this is how we deal with it. As long as the anti-D is detectable we consider it as we would any other anti-D to include full AHG crossmatches. When it finally goes away we we remove the anti-D from the patient's computer record. Our contention is that it is still anti-D and it is detectable, you must acknowledge it. Now on the flip side, what's the chance of transfusing an Rh neg women of childbearing years with Rh pos blood? Pretty slim I would hope so I really can't justify our approach logically. It was just the easy way out.

[csjuarez]

I agree that if it is known that a patient has received RhIg recently, there should be some annotation that the anti-D is possibly due to the RhIg injection. We have a separate antibody ID result "RhIg D" which is set up differently from the allo anti-D and also add the comment "most likely due to RhIg". By having the separate response set up in our computer, we can set it like antibodies such as anti-Le where if the current antibody screen is negative you don't have to do the Coombs crossmatch. We're not set up to do the electronic crossmatch (yet), so I'm not sure exactly how that will work out then. I don't think it is a good idea to "erase" the anti-D results from the computer system, though, whether or not it is known to be alloantibody.

[gonneb25]

Do you provide CDE neg units for all patients that have anti-D and anti-D due to RhIg? We do AHG xms only for the "true D's" and use IS xm's for the RhIg patients. But, for both we always give C and E neg units too (we need to rule out on one homozygous cell and you cannot rule out C or E that way with someone who has anti-D). I am contemplating going to IS xm's with no antigen screening required for the OB patients with RhIg. Any thoughts on this?

[labgirl153]

My facility also performs a select cell panel for these cases, with the disclaimer in the workup of "anti-D probably due to Rhogam" but only if we can document when the last dose was injected. If not we assume the mother has a true anti-D and we go from there (i.e. perform a titer to get a better idea of what we have). We also perform gel x-matches on these mothers if the M.D. orders blood, but don't tie up Rh neg units otherwise.

Our dilemma came when we considered performing DATs using the gel methodology on the infants of these passive anti-D mothers. Since gel is very sensitive, it picks up the mother's passive anti-D coating the baby's cord cells, vs. the tube method, which rarely picks this up. We hated the idea of reporting out positive DATs on these infants from gel when we knew it was passive anti-D (not a true D) coating the cells and that it would be of no consequence to the baby. That is, we didn't want to confuse the medical staff with this "extraneous info". Instead, we still perform the cord cell DATs with tube (IgG only) in cases where the mother has been shown to have only a passive anti-D. If there's something significant coating the cord cells, a tube DAT should detect it, so we're not concerned about "missing" something.

[Rita]

We also have seen many more passive Anti-D probably due to Rhogam since we started using the MTS gel system. Does anyone out there, when they know a woman has recently received Rhogam (within the last few months), use a method for the antibody screen (like LISS) that is less likely to detect the Anti-D due to Rhogam? instead of their routine testing method (like MTS gel)? I'm very curious to know. Thank you.

[EdSandlin]

Our facility requires an antibody screen to be drawn prior to admistration of Rho-Gam (i.e. the same day). That way we have explicit record of the antibody status of the patient and can subsequently just run the "mini rule-out" panel that others have mentioned. Our computer system then will accept an electronic crossmatch after the "Anti-D probably due to RhIg" answer is entered. I'm ignorant of a screening method that would exclude Rho-Gam, and frankly skeptical that it would be trustworthy not to exclude significant antibodies.