Blood volume changes in pregnancy and the puerperium: II. Red blood cell loss and changes in apparent blood volume during and following vaginal delivery, cesarean section, and cesarean section plus total hysterectomy

Abstract

Blood volume changes were studied in 150 parturient women to determine the fate of the blood added to the circulation during pregnancy as well as to quantitate blood loss associated with delivery. Previously it was shown that when chromium-labeled red blood volume there was good agreement between the volume of red blood cells that disappeared from the circulation and the volume of red blood cells lost during parturition. This technique was used in the study. In 75 women during and very soon after vaginal delivery red blood cell loss from the circulation was equivalent to 505 ml of predelivery blood. In 40 women undergoing repeat cesarean section prior to labor the average loss equaled 930 ml of predelivery blood. In 35 other women subjected to cesarean section plus total hysterectomy the average loss equaled 1435 ml of predelivery blood. Between the first hour after vaginal delivery and 72 hours later in 54 women an average of 80 ml of blood was collected from the vagina. With 1 exception oxytocics were not administered except at the time of placenta delivery. In essentially normal pregnant women the loss of 20-30% of the predelivery blood volume as the result of parturition typically produced little change in the hematocrit during the puerperium. It is concluded that in general women during and after parturition can tolerate the loss of most of the blood added to the circulation during pregnancy without serious effects. In a discussion R.G. Holly notes 1) the need for studying long-term effects of acute blood loss and 2) that this study is a good example of using isotopes to obtain precise information. J.L. McKelvey comments on iron storage in patients whose hemoglobin mass does not increase. C.J. Lund notes that postpartum changes in hematocrit are not unpredictable if total blood volume is considered.