Investigation of Apparent Solid Phase-Only Red Cell Serologic Reactivity: Clinical and Laboratory Correlations

Solid phase red cell adherence is a sensitive platform for blood group antibody detection, but non-specific reactions may occur. The aim of this study was to define the clinical characteristics of patients with these reactions and their associated laboratory findings.

An 8-month retrospective review of a regional blood bank database was performed. One hundred and seventy-three patients were identified with apparent nonspecific solid phase (NSP) reactivity. Serologic findings were recorded, and each patient's electronic health record was interrogated.

NSP reactivity was the most common positive finding in the laboratory. Of 173 patients with NSP, 167 had documented concurrent tube testing. Of these, 165 were negative, one demonstrated nonspecific reactivity, and one anti-Lea was identified. Most positive solid phase antibody screens had negative panel testing, with fewer cases of pan-reactivity or sporadic reactivity. Follow-up testing was either negative (85.5%) or demonstrated NSP reactivity (14.5%). No new blood group antibodies were identified. Most patients were female (72.8%), with pregnancy being the leading diagnosis (35.8%); however, this mirrored the distribution of cases received in the laboratory. When pregnant patients were excluded, female and male patients had the same average age, and the gender distribution and the primary diagnoses of NSP patients mirrored those of all patients evaluated.

Solid phase antibody detection is known to be sensitive, but nonspecific reactions are relatively common. Compared to other studies, the evolution of NSP to clinically significant antibodies was not seen, female patients did not have a predilection for NSP reactivity, and NSP was not associated with certain diagnoses.