Currently, when we have a patient suspected of having a passive anti-D, the techs perform a 1:4 dilution and repeat the antibody screen. If the 1:4 diluted screen is negative, they verify the administration of RHIG and call the antibody passive anti-D. This is a procedure that has been in place for approx. 10+ years and I don't like it. I couldn't find any literature or documentation of this beeing acceptable practice (I checked several old Tech Manuals from the 1980's also). Does anyone knows where this practice may have come from.

I come from the school of ID all antibodies using the traditional panel method and verify the administration of RHIG before calling the antibody passive anti-D. One facility that I worked at we did a selected cell panel with a minimum of 6 cells. Our D+ cell was always Ror with the remaining cells being negative for D and homozygous positive for all other major allos (2 hetero Kell cells were used if no homozygous cell available). If only the Ror cell came up positive, we verified the administration of RHIG and then called the antibody passive anit-D. If the RHIG was issued by our facility, then the selected cell panel was performed. If the RHIG was not issued by our facility, a full panel was run.

I am in the process of updating this procedure (and all procedures in the department) and wanted to know how others out there in BB land handle the identification of passive anti-D.

We run a panel on all positive antibody screens. If we have confirmation that the patient has received RhIg, and the antibody screen is positive for 2 of 3 cells (looks like an anti-D), we do an abbreviated panel (cells 5-8 of 0.8% Resolve Panel A in the gel) to rule out anything else. We do the same whether or not we gave the RhIg at our hospital. Then we report it as "Anti-D by RhIg".

If you use the Ortho A panel, there are 4-5 cells with an ampersand (@) next to them. On the reverse of the panel sheet it explains that you may use these as a minipanel to r/o anti-D. I select 4-5 cells to run when we anticipate that we are seeing residual antenatal RhIg. I don't worry about r/o anti-Kpa,-Jsa,-Lua.

When we used tubes, we would repeat the screen using a 1:28 dilution and reported like you said. I don't know where this came from but we used it for many years until we switched to gel. Now we run the full panel and confirm the patient did receive RHIG. We report "Residual-D - patient received RHIG on dd/mm/yy".

Shaundrey -

I have never heard of the protocol you discussed to report out "Passive Anti-D". I think it sounds risky and I don't see any advantage of it. We would do a regular panel or an abbreviated panel of 3-5 cells (as described by tbostock & David Sakin above.)

Thanks everybody for the responses. I'm not sure where this procedure came from and neither did one of the long term techs (she has been here close to 30 years). Since we are a primary gel use site, we are going to lose this 1:4 dilution in the tube.

We always do full ID's on positive screens.

The Technical Manual states that passive anti-D is IgG only, usually weakly reactive at IAT with a titer of less than or equal to 1:4.

Using this statement as the reference, our policy is:

If only weakly reactive in IAT and history of RhIG, we report passive

If the anti-D reacts at any phase other than IAT (IS or 37C), or if strength is greater than 2+, a titer is performed.

If the titer is 1:4 or less, and a history of RhIG, we report passive.

If greater than 1:4, the supervisor or pathologist makes the decision to consider immune and withhold RhIG.

When in doubt, RhIG is given.

BTW - We had a baby whose Bilirubin rose to 8.7 from passive RhIG (titer 1:2). Anti-D eluted from baby's cells.

Edited October 21, 200915 yr by GilTphoto

We call L&D and/or the DR's office anytime we get a positive screen that appears to be "Anti-D". We don't work it up at all. We note the date of Rhig administration and add to the patient's report that it is "presumably due to Rhig administration on _____date".

I don't understand not working it up. How do you tell from a 2 or 3 cell screen that it "appears to be anti-D"?

When a mother comes in to deliver, we do a Type and Screen. If the screen is positive, we have to ID and crossmatch 2 units, if she bleeds during or after delivery.

In addition to having blood available for her, we need to know if other significant antibodies are there, so we can test the baby for the antigen.

If this was an antepartum RhIG request, the doctor should still know about other antibodies, to monitor for HDN.

If it is a Rhogam work up (after delivery work up on mom) we perform the screen on the @ cells from the Ortho A panel- but only if the baby's DAT is negative. If the baby has a positive DAT, we do a regular 3 cell screen in gel and would then do a full panel if we got a positive. We order an elution on the baby and send the mom's blood out to our reference lab for a HDN titer for anti-D.

If it is for a crossmatch, we always do a regular antibody screen and panel work up if needed. We just had one of these yesterday. We had antigen test the units for C and E because they could not be ruled out with the Anti-D coming through.