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.

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.

The short shelf life of platelets makes providing ABO-compatible platelets a challenge, and many institutions issue ABOincompatible 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. Immunohematology 2019;35:91-94.

A 54-year-old man presented to the Emergency Department for left lower extremity pain and swelling. The patient's medical history included peripheral vascular disease with a chronic non-healing venous stasis ulcer of the left lower extremity, as well as mechanical aortic valve replacement with ongoing warfarin anticoagulation. While being examined, the patient had a spontaneous episode of epistaxis. Laboratory testing revealed an International Normalized Ratio (INR) of greater than 8.18 (normal 0.85-1.15) and a prothrombin time of greater than 100 seconds (normal 9.4-13.0 sec). The patient's supratherapeutic INR was treated with 10 mg intravenous (IV) phytonadione (vitamin K) (AquaMEPHYTON) in 50 mL sodium chloride 0.9%. A type and screen was sent to the blood bank laboratory in anticipation of plasma transfusion. Following centrifugation, a bright yellow discoloration of the plasma was noted (Fig. 1). Further investigation revealed that the type and screen was drawn concurrently Fig. 1. Patient type and screen specimen, plasma.Fig. 2. Phytonadione (vitamin K) (AquaMEPHYTON).

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 methodspecific 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 solidphase 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.