Effects of hydroxyethyl starch on erythrocyte typing and blood crossmatching

Venous blood was mixed with varying amounts of 6% hydroxyethyl starch solution in vitro and also blood samples were obtained from leukapheresis donors who had received infusions of hydroxyethyl starch. These specimens were evaluated as to the accuracy of erythrocyte typing, direct antiglobulin-testing, and antibody detection using saline, albumin, low-ionic strength saline and papain media. Specimens were stored at 4 degrees C, and testing was repeated at intervals during one week. Moderate difficulties were encountered, due to rouleaux formation, in the interpretation of typing and antibody screening in some samples that contained greater than 30 percent of the hydroxyethyl starch solution. Rouleaux formation was readily dispersed with saline and could easily be distinguished from true agglutination by microscopic examination. Although the apparent difficulties were not extreme, blood bank personnel should be alerted to the potentially misleading effects of hydroxyethyl starch on test results.