Anti-D Antibody Panels In OB Patients

[LisaM]

I've already run this one by Malcolm, by email, but wanted to see what everyone else thinks about it:

We've had a go-around at work regarding the procedure for running panels on OB patients with a suspected anti-D. The way our procedure is, if we suspect a D, we are supposed to run only the 3 or 4 "@" designated cells on the panel, and if they're all negative, call it a D and you're done. This is regardless of whether or not it's a first time panel or a subsequent one on the patient.

My prior training was to perform a full panel on anyone, any antibody if it's a first time panel, then use selected cells to rule out on subsequent panels, making sure you account for homozygosity on those that can show dosage. All other area labs are doing it this way, and our procedure is being defended as correct because

A. All the other labs are automated and have no choice but to run a full panel (which I wonder about. . . ) and

B. If there's another antibody there, and it's too weak to react with heterozygous cells on those "@" cells, then it's too weak to titer, too weak to be of concern, and will be picked up later in the pregnancy if it gets stronger.

I'm not at all comfortable with this, because I feel it's setting us up to miss something, and cutting corners in the name of saving money on supplies. I've said my peace at work, and the topic and situation have been laid to rest/diffused, so I'm not going to push this one anymore. I'll do as I'm told and only sign my name to them when I have to (stats and other unavoidable sign-outs), but I wanted to toss this out there to see what everyone else's take on it is.

[JOANBALONE]

Hi Lisa,

Do you run a 2 or 3 cell screen?

JB

[David Saikin]

When I have an OB pt who appears to have anti-D releated to residual antenatal RhIg (1-2+ in gel with scr cell 1 and/or 2), I run an abbreviated panel which r/o all the clinically significant abs - this is usually 5 cells. We only do this on OB admissions who have T&S oders. As with any anti-D discovered, have to r/o C/E with heterozygous cells.

[applejw]

I'm not as concerned about whether or not I'm running a "full panel" as to whether or not I'm running enough cells to exclude antigens to the commonly encountered alloantibodies. Usually manufacturers will designate the 3-5 cells on their panel that may be used in the presence of anti-D - these cells are usually appropriately homozygous for Kidd, Duffy, MNSs, Lewis and include heterozygous C and E. I would be more concerned about the quality of the cells that are being run, rather than the idea of the "full panel". If the selected cells cover all bases, then that should be sufficient (I'm of the old school that likes to see 3 positive cells to call the antibody so still require a 3rd D+ cell to conclude that it is anti-D - passive or immune - matters not!)

We run antibody identifications on all antepartum OB patients - yes, most often it is a full panel because we do use the Galileo - but for those samples that come in and can't be run on the instrument - we will do the workup which doesn't require a "full panel" but we have to run sufficient cells to cover all the antigens with the required zygosity.

Hopefully this helps....

I've already run this one by Malcolm, by email, but wanted to see what everyone else thinks about it:

We've had a go-around at work regarding the procedure for running panels on OB patients with a suspected anti-D. The way our procedure is, if we suspect a D, we are supposed to run only the 3 or 4 "@" designated cells on the panel, and if they're all negative, call it a D and you're done. This is regardless of whether or not it's a first time panel or a subsequent one on the patient.

My prior training was to perform a full panel on anyone, any antibody if it's a first time panel, then use selected cells to rule out on subsequent panels, making sure you account for homozygosity on those that can show dosage. All other area labs are doing it this way, and our procedure is being defended as correct because

A. All the other labs are automated and have no choice but to run a full panel (which I wonder about. . . ) and

B. If there's another antibody there, and it's too weak to react with heterozygous cells on those "@" cells, then it's too weak to titer, too weak to be of concern, and will be picked up later in the pregnancy if it gets stronger.

I'm not at all comfortable with this, because I feel it's setting us up to miss something, and cutting corners in the name of saving money on supplies. I've said my peace at work, and the topic and situation have been laid to rest/diffused, so I'm not going to push this one anymore. I'll do as I'm told and only sign my name to them when I have to (stats and other unavoidable sign-outs), but I wanted to toss this out there to see what everyone else's take on it is.

[LisaM]

Joan--we run a 2-cell screen, and in gel, as that's our primary. We only switch to tube on occasions when it may be helpful to see those reactions, or we're having a problem workup in gel, etc.

Apple--thanks and I agree! I've been running about 6 cells to ensure a cautious rule-out, as the 3 @ cells on our panel do not allow for a homozygous rule out of things such as "S", or both Duffy's or Kidd's. I was being told that that was running too many cells, and it wasn't even a full panel, and to stick to just the 3, but after speaking with the supervisor yesterday, she compromised on allowing one additional cell to make sure both Kidds are ruled out with homozygous cells, as that's the only one she's concerned with.

[JOANBALONE]

Hi Lisa,

You routinely rule out on heterzygous cells all day if you use a 2 cell screen. If the patient has recently received RhIG it is expected to be in the plasma. I have no problem using the cells designated with @ to rule out any unexpected antibody even though some may have heterozygous expressions (just like the screening cells). I consider the cells designated with @ as an extended screen. What does your antibody identification procedure state?

JB

[LisaM]

Hi Lisa,

You routinely rule out on heterzygous cells all day if you use a 2 cell screen. If the patient has recently received RhIG it is expected to be in the plasma. I have no problem using the cells designated with @ to rule out any unexpected antibody even though some may have heterozygous expressions (just like the screening cells). I consider the cells designated with @ as an extended screen. What does your antibody identification procedure state?

JB

Our procedure states that to rule out Kidds, Duffys, and MNS system, we need only one cell to rule out, but we must always use homozygous cells and never heterozygous. With everything else, if there's one homozygous to rule out with, that's fine, but if not, then 2 heterozygous are acceptable.

That's where a bit of a procedural contradiction comes in--some of those @ cells don't allow for the homozygous rule out, yet we're supposed to accept it based on the disclaimer within the procedure of that being ok for the anti-D scenario.

[JOANBALONE]

Perhaps you can add to your procedure that if patient has received RhIG in last 3 months that the cells indicated with @ may be used to rule out unexpected antibodies?

[LisaM]

Perhaps you can add to your procedure that if patient has received RhIG in last 3 months that the cells indicated with @ may be used to rule out unexpected antibodies?

I think that's already there, because it also states that if the Rhogam history is known, then the 3 @ cells are to be used regardless of whether it's a first time panel, or subsequent one. If there's no history of Rhogam or it's unknown, then we are allowed to do a full, 11-cell panel.

[John C. Staley]

Just curious and trying to stir the pot a little. Other than the issue of RhIG, why, when it comes to identifying antibodies, would you want to treat an OB patient any different than the rest of you patients you suspect / know have and anti-D?

[macarton]

We run the 5-8 cells indicated on the Ortho panel on all Rh negative OB's coming into L&D with a comment, not screened for D. If the infant has a positve DAT, we do an elution and report the antibody if eluted.

[Malcolm Needs ☆]

If the infant has a positve DAT, we do an elution and report the antibody if eluted.

Just as a matter of interest Mary, what do you do if the antibody is not eluted? Do you test for ABO HDN and, against Dad's red cells, antibodies directed against low incidence antigens?

I, by the way, wouldn't bother unless the baby is clinically affected, but I just wondered what you do.

[JOANBALONE]

Just curious and trying to stir the pot a little. Other than the issue of RhIG, why, when it comes to identifying antibodies, would you want to treat an OB patient any different than the rest of you patients you suspect / know have and anti-D?

Hi John,

I don't consider this treating OB patient's any different than others. Anti-D is expected (and in my opinion, clinically insignificant) in these patients that have recently received RHIG. We just modify our antibody screen (using the cells designated by @) to rule out all other antibodies.

JB