66 patients in hematology / oncology departments , including 20 patients with a hemoglobin significantly below the norm (<8g / dl hemoglobin in the blood), and about to receive a transfusion. 20 patients hospitalized in gastroenterology with a transfusion need 4 internal medicine patients with cold agglutinins, in a transfusion context or not.  10 neonatal patients, background transfusion or Guthrie test.