Total Blood Volume Is Maintained in Nonhydropic Fetuses with Severe Hemolytic Anemia

Abstract

Objective: Fetal alloimmune anemia is associated with increased blood flow velocities and cardiomegaly. In severe cases, hydrops can develop. We investigated whether the decrease of red blood cell volume is associated with a reduction or expansion of plasma volume. Methods: In 86 alloimmunized fetuses that received a first intrauterine transfusion, we calculated fetal total blood volumes (i.e. fetoplacental blood volumes) using a dilutional principle of fetal hemoglobin with adult hemoglobin. The relation between total blood volume and estimated fetal weight, severity of anemia and hydrops was analyzed. Results: Gestational age ranged from 17 to 35 weeks. Mean hemoglobin deficit was 6.8 standard deviations (range 2.1–11.7) below the normal mean. Fetal total blood volume was significantly related to estimated fetal weight (p < 0.001). Mean total blood volume in nonhydropic fetuses was 123 ml/kg (n = 74) and in hydropic fetuses 144 ml/kg (n = 12). There was a significant relation between total blood volume per kg body weight and hydrops (p = 0.035); however, there was no relation with severity of anemia (p = 0.94). Conclusion: In the human nonhydropic fetus with severe hemolytic anemia, total blood volume is maintained: the decrease in red blood cell volume is thus compensated by an increase in plasma volume. In hydropic fetuses, however, total blood volume seems to be increased. This is in accordance with the hypothesis that congestive heart failure plays a role in the pathophysiology of hydrops in anemic fetuses.

Fluid shift from intravascular compartment during fetal red blood cell transfusion

“…Usually, Rodeck's formula underestimates the donor volume required to reach the desired hematocrit because the formula does not take into account the increase in blood volume during transfusion. Furthermore, the normal values found by Nicolaides were somewhat lower than we have calculated 6,11 . Packed red cells, with a hematocrit of around 80%, are usually transfused with a 22-gauge needle until about 26 weeks' gestation and subsequently with a 20-gauge needle for older fetuses, at 5 mL/min, depending on fetal heart rate stability.…”

“…Fetuses below 20 weeks' gestation were transfused with relative speeds up to five times higher than were fetuses above 32 weeks. Higher gestational age increases fetoplacental blood volume exponentially because it is linearly correlated with fetal weight. Low gestational age is a risk factor for complications in intrauterine transfusion because of procedural difficulties, and administering donor blood at the same speed is a heavier burden in younger fetuses.…”

“…Animal experiments have demonstrated that fetal hematocrit further increases in the first hour after transfusion. Although total blood volume was not yet normalized after 24 h, in human fetuses the total blood volume was maintained in different degrees of anemia. Thus, it can be expected that a return to initial fetoplacental blood volume takes place within a limited time after transfusion, resulting in an increase in hematocrit.…”

Fetal transfusion: the spectrum of clinical research in the past year

“…Pasman et al [11 ] conducted a retrospective study of 86 alloimmunized fetuses and calculated total fetal blood volume at their first intrauterine transfusion with an equation proposed by Hoogeveen et al [12]. There was no relationship between total volume and severity of anemia.…”

Development of a Novel Maternal-Fetal Physiologically Based Pharmacokinetic Model I: Insights into Factors that Determine Fetal Drug Exposure through Simulations and Sensitivity Analyses

“…Fetal rest of body compartment was back-calculated as fetal weight [based on published fetal volume formula(Abduljalil et al, 2012) assuming a 1 mg/ml density throughout gestation] minus the sum of fetal organ volumes and fetal blood volume [based on the reported average fetoplacental blood volume of 123 ml/kg fetal weight during the second and third trimesters(Pasman et al, 2009)]. A PBPK Model of Factors Determining Fetal Drug Exposure 925 at ASPET Journals on October 11, 2020 dmd.aspetjournals.org…”