Dansket

Replacing the balance card is on my monthly QC checklist.

Correct, there is no such thing as "anti-Weak D", but the Weak D test is done and it is interpreted as either "positive or negative" (assuming a negative control test). Procedurally, if a Weak D test on a blood sample (that gave a macroscopically positive immune resetting test) is also agglutinated (usually =>2+) , I will interpret that test result as a "positive Weak D test" or "Weak D positive" and report the patient to be Rh Positive.

I think the terms "strongly positive" or "diffusely positive" do not accurately describe the results of an immune resetting test on a Weak D positive blood sample. By definition, the test is routinely read with a microscope. An unexpected result is macroscopic agglutination and this is what we see with a Weak D positive and D positive blood samples. Our procedure states that if macroscopic agglutination is observed in the immune resetting test, then a Weak D test is indicated for that blood sample.

Remember that 1+, 2+, 3+ and 4+ are test results and that test results may be interpreted accordingly to the test being performed and to the user's protocol for Rh grouping. For example, the ORTHO Gel Anti-D direction insert states that agglutination observed in the anti-D gel column should be interpreted as Rh positive (assuming a negative control test), but some users may interpret weak agglutination ( less than 2+) in Anti-D Gel as Rh negative.

JoJo808, Which test method is used for routine testing at your facility? Were the "suspicious results" only observable by microscope? Were the night tech's "suspicious test results" reproducible? Based on my routine testing protocol and detailed protocols for investigating "positive" antibody screens (that includes criteria for referring samples to a reference laboratory), I would not flag a patient with a history of "inconclusive antibody identification" for antiglobulin-crossmatching-in-perpetuity when subsequent antibody screens are negative. It all depends on how well you feel your test system performs. If I didn't have a tightly controlled system, I might choose to require routine antiglobulin crossmatches in perpetuity for patients with a single positive antibody screen attributed to an "inconclusive antibody identification".

As long as the antibody screen is positive and/or your computer system is configured to classify an "inconclusive antibody identification" as "clinically significant".

@galvania

How does the ionic-strength of 50uL of plasma differ from 50uL (25uL of plasma + 25uL of Buffered Saline)? I understand the importance of maintaining a low-ionic strength environment for indirect antiglobulin testing at 37C in Anti-IgG Gel, but not in direct agglutination tests at room temperature in Buffered Gel. Historically, low-ionic strength test systems were not implemented in direct agglutination test systems. Please elaborate.

SOP for ABO Plasma Grouping in Gel requires 50ul of plasma. When unexpected agglutination (suspected presence of rouleaux) occurs performing ABO Plasma Grouping in Gel, would it be useful to repeat the test in Gel using 25uL of plasma and 25uL of 0.9% buffered saline as an investigative tool?

If I were sending samples to a reference lab to test for a large fetal-maternal hemorrhage, I would skip the rosette test and do the Kleihauer-Betke test in the interests of speed, efficiency and a final result.

What has been your experience with microscopically (only) positive direct antiglobulin tests? Does anyone have any long-term data supporting the clinical significance of a positive DAT test that is detectable only by a microscope? Do you report these as positive in the say way as you would report a macroscopic result of 1+ to 4+?

If current antibody screen is positive and Lewis antibody identified, do immediate-spin and anti-igG crossmatches, issue crossmatch-compatible random donor units. If current antibody screen is negative and there is a history of Lewis antibody, do Computer Crossmatch with random donor units.

Should the blood spot be taped on both sides of the paper routinely or be based on procedure criteria?

I call them weakly-reactive, while antibody screens that are 3+ to 4+ are termed strongly-reactive. Either way, they are documented in the computer as "Positive". In my experience (20+ years with gel), the majority of positive antibody screens detected in gel were weakly-reactive. As trained observers, we expect to see strong agglutination (3+ or 4+) when performing Rh(D) typing with anti-D reagent antisera. Weak agglutination (<3+) is unexpected and should be investigated. Judd's paper provided statistical evidence for interpreting weakly-reactive test results with gel anti-D. ORTHO's current IFU (version 3.0) classifies any positive test result (regardless of strength) with gel anti-D as Rh Positive (assuming a negative control test). Judd's paper is not cited in the IFU's Bibliography. Interpreting weakly-reactive test results with gel anti-D as 'Rh Negative' contradicts ORTHO's FDA approved IFU.

You didn't say how large your laboratory is and how Transfusion Services is staffed on the night shift. When I was doing manual testing, it was consistent with your new supervisor's approach. An autocontrol was only run with the first panel only. With automated gel testing on ProVue, only full panels can be run. Rule-outs are done by entering panel test results into the AntigenPlus antibody identification software. A maximum of 3 panels would be run before sending specimen to reference lab. This standardized protocol was used in a small hospital transfusion service (<1000 rbcs transfused annually) staffed with generalists. This protocol was easily followed, even with only 1 generalist on staff at night for the entire laboratory.