Blood volume changes and blood loss associated with labor: I. Correlation of changes in blood volume measured by I131-albumin and Evans blue dye, with measured blood loss

Abstract

Pre- and postdelivery blood volume measurements were made on 21 women with the I131-albumin (RISA) and Evans blue dye techniques. All the blood lost in between the 2 measurements was collected and measured by the cyanmethemoglobin method. The results showed that the blood volume decreased by an average amount of 1,115 ml. with the RISA method and 1,023 ml. with the Evans blue dye method. The measured blood loss was 1,006 ml., or 1,106 ml. when the estimated amount of maternal blood in the placenta was included. These findings show that the difference between pre- and postdelivery blood volumes is due to the blood loss associated with labor, and not to sequestration of red cells. The results also suggest that the average amount of blood lost during delivery is greater than is presently estimated and is probably in the region of 1,000 ml.