Dilution is not the solution: acute hemolytic transfusion reaction after ABO-incompatible pooled platelet transfusion.

CONCLUSIONS: The short shelf life of platelets makes providing ABO-compatible platelets a challenge, and many institutions issue ABO-incompatible platelets when compatible units are not available. It is presumed that ABO antibodies that exist in donor plasma are diluted when platelets from multiple donors are combined to make a pooled product for transfusion. We present a case of a hemolytic transfusion reaction in a 73-year-old man with myelodysplastic syndrome who received an ABO-incompatible pooled platelet unit. This case report demonstrates that the dilution theory is not always true for pooled platelet units, and any patient receiving ABO-incompatible platelet transfusions must be closely monitored for potential hemolytic transfusion reactions.

Method-specific and unexplained reactivity in automated solid-phase testing and their association with specific antibodies.

CONCLUSIONS: The inherent tradeoff between sensitivity and specificity in the detection of unexplained antibodies has been the objective of many studies, editorials, and journal articles. Many publications note that no method is capable of detecting all clinically significant antibodies while avoiding all clinically insignificant antibodies. This study describes the frequency of nonspecific reactivity and unexplained reactivity in solid-phase testing, along with the subsequent development of specific antibodies (Abs). In this study, nonspecific reactivity (NS) is defined as method-specific panreactivity detected by solid-phase testing only, with no reactivity in other methods. Unexplained reactivity (UR) is defined as reactivity present and detectable in all test methods after all clinically significant antibodies were ruled out following a standard antibody identification algorithm using selected cell panels. This retrospective study evaluated antibody detection tests of patients at a single center for 2 years using two automated solid-phase instruments that used the same three-cell antibody detection test. Antibody identification was performed with solid-phase panels supplemented with a polyethylene glycol tube method as needed. Of the 1934 (5%) samples with a positive antibody detection test, 29 had unavailable work-up data, leaving 1905 (98.5%) samples eligible for inclusion in the study. The data revealed the following: Ab only 999 (52.4%); UR only 429 (22.5%); Ab and UR 227 (11.9%); NS only 206 (10.8%); Ab and NS 24 (1.3%); UR and NS 14 (0.7%); and Ab, UR, and NS 6 (0.3%). Patients with a positive follow-up antibody detection test had UR and NS replaced with a specific Ab in 23 of 656 UR (3%) and 8 of 230 NS (3%) cases, respectively. Additionally, six patients with UR developed a specific Ab along with persistent UR, and no patients with persistent NS developed a specific Ab. The study concluded that both UR and NS can be encountered in solid-phase testing, and both UR and NS can persist in follow-up testing. Specific Ab was observed to replace UR in a few patients.

Evaluation of different testing methods for identification of RhIG in red blood cell antibody detection.

BACKGROUND: RhIG has had great success in protecting fetuses from potential harm; however, little work has been done to demonstrate how long RhIG reactivity is detected in the mother after administration when using common red blood cell antibody detection methods. STUDY DESIGN AND METHODS: A retrospective investigation was performed examining positive antibody identification panels due to RhIG. These panels were run on solid-phase (SP) testing. The time to a positive result, length of detection, and positive strength of reactivity (PSR) were evaluated. Additionally, a comparative study was performed evaluating how sensitive SP, gel (GT), and tube testing (TT) were at detecting RhIG using serially diluted plasma samples spiked with different RhIG formulas. RESULTS: Retrospectively, most antibody identification panels by SP were positive 3.5 months after RhIG administration and demonstrated a strong PSR. The longest recorded positive panel was present at 4.5 months. RhIG administered intramuscularly could not be detected until several hours after injection. The comparative study showed that SP was the most sensitive method while GT and TT were comparable to one another in detecting RhIG. SP also recorded strong PSR at very low concentrations of RhIG. GT and TT recorded weak PSR even with higher concentrations of RhIG. CONCLUSION: SP is the most sensitive testing method and has the ability to detect RhIG 4 to 5 months after administration. TT and GT have the ability to detect RhIG up to 3 to 4 months after administration. Different RhIG formulas may show slightly different lengths of detection.

Safety of a liberal policy for extended-date preadmission testing samples.

BACKGROUND: Regulations governing pretransfusion testing allow specimen expiration to be extended past 3 days before the transfusion if a patient has not been transfused or pregnant in the preceding 3 months. Our hospital allows extension of the expiration of a presurgical specimen to 28 days if 1) the patient has neither been transfused nor pregnant in the past 3 months, 2) the patient does not have an antibody history, and 3) the current antibody screen (ABSC) is negative. Patients not meeting Criteria 2 and 3 are required to have specimens redrawn on the day of surgery (DOS). We evaluated the necessity of this policy. STUDY DESIGN AND METHODS: From October 2009 to September 2010, there were 132 patients who did not meet the above criteria for specimen extension. Equivalent tests were performed on preadmission testing (PAT) and DOS specimens, and the results were compared. RESULTS: The majority (113, 86%) of the samples redrawn on the DOS showed no change in antibody serology upon reinvestigation. Of the remaining patients, DOS specimens did not identify any new antibodies or change in blood product choices. CONCLUSION: Of the PAT specimens rejected for antibody history or positive ABSC, none had new significant serologic findings on DOS. Based on these results, requiring a repeat specimen on the DOS may not be clinically necessary. Our facility changed the PAT policy to extend specimen acceptability to patients with red blood cell antibody history or positive ABSC at time of PAT. A 6-month follow-up period showed that this practice is safe.