Hemoglobin equilibration after transfusion in stable postpartum patients

Hemoglobin levels are typically checked 4 h after transfusion to assess response, but this delay is unnecessary in nonpregnant adult patients. It remains unclear if postpartum patients need time for hemoglobin levels to stabilize due to post-delivery pregnancy physiology. This study aims to determine if immediate reassessment of hemoglobin following transfusion is sufficient for postpartum patients.

This is a single-center, prospective study from February to July 2025 in which serial hemoglobin assessments (immediate, 4 h, 12 h after transfusion) were completed following the transfusion of packed red blood cells (PRBCs). Exclusion criteria were the following: hemodynamic instability, >72 h from delivery, massive transfusion protocol activation, more than four units PRBC transfused, or missed lab draw timing >15 min. Power analysis determined that 23 patients would be needed for 80% power to detect a difference of 0.6 g/dL using paired t-tests with a two-sided p value of <0.05.

Twenty-four participants met the criteria and were enrolled. When compared to 12-h posttransfusion hemoglobin, there was no difference between hemoglobin concentration in g/dL between the immediate (0.08 g/dL; 95% confidence interval [CI], -0.44 to 0.26) and 4-h posttransfusion (0.10 g/dL; 95% CI, -0.41 to 0.21) values. The mean immediate rise in hemoglobin for those with one unit transfused was 0.97 g/dL (95% CI, 0.48-1.45) and for those with two units transfused was 1.99 g/dL (95% CI, 1.26-2.71).

Our findings indicate that hemoglobin equilibration occurs rapidly following PRBC transfusion in stable postpartum patients, and that an arbitrary 4-h delay after the completion of transfusion before laboratory reassessment is not necessary. Earlier evaluation of response to transfusion could prevent delays in anemia management.