Acute fetal hemodynamic alterations after intrauterine transfusion for treatment of severe red blood cell alloimmunization

Automated quantitative evaluation of fetal atrioventricular annular plane systolic excursion before and after intrauterine blood transfusion in pregnancies affected by red blood cell alloimmunization

INTRODUCTION

Maternal red blood cell alloimmunization during pregnancy can lead to hemolysis and various degrees of fetal anemia, which can be treated with intrauterine blood transfusion (IUT) to prevent adverse outcomes. Knowledge about fetal myocardial function and adaptation is limited. The aim of the present study was to measure fetal atrioventricular plane displacement before and after IUT and compare these measurements with previously established reference ranges.

MATERIAL AND METHODS

An observational study was conducted on pregnant women affected by red blood cell alloimmunization. Fetal echocardiography was performed before and after IUT. The atrioventricular plane displacement of the left and right ventricular walls and interventricular septum, described as mitral, septal, and tricuspid annular plane systolic excursion (MAPSE, SAPSE, and TAPSE, respectively), was assessed using color tissue Doppler imaging with automated analysis software. A Mann-Whitney U test was used to compare the z scores to the normal mean before and after IUT.

RESULTS

Twenty-seven fetuses were included. The mean z score for pre-IUT MAPSE was significantly increased compared with the reference ranges, +0.46 (95% confidence interval [CI] +0.17 to +0.75; p = 0.039), while the mean z scores for post-IUT SAPSE and TAPSE were significantly decreased, -0.65 (95% CI -1.11 to -0.19; p < 0.001) and -0.60 (95% CI -1.04 to -0.17; p = 0.003), respectively. The difference in atrioventricular plane displacement z scores before and after IUT was statistically significant in all three locations. The median difference between the pre-IUT and post-IUT z scores was -0.66 (95% CI -1.03 to -0.33, p < 0.001) for MAPSE, -1.05 (95% CI -1.43 to -0.61, p < 0.001) for SAPSE, and -0.60 (95% CI -1.19 to -0.01, p = 0.046) for TAPSE.

CONCLUSIONS

This study suggests that atrioventricular plane displacement, when determined using automated analysis software, may represent a quantitative parameter, describing fetal myocardial function and adaptation before and after IUT.

Minute Stroke Distance Is a More Reproducible Measurement Than Cardiac Output in the Assessment of Fetal Ventricular Systolic Function

BACKGROUND

Echocardiographic quantification of fetal cardiac output (CO) aids clinical decision-making in the management of various cardiac and extracardiac diseases. Small variability in measuring semilunar valve dimension significantly reduces the reproducibility of the calculated CO. The authors propose minute stroke distance or velocity-time integral (VTI) as a more reproducible measure reflecting fetal ventricular systolic function. The aim of this study was to test the hypothesis that right and left ventricular minute VTI increase predictably with estimated fetal weight and are more reproducible than CO.

METHODS

Five hundred seventy-one singleton fetuses without cardiovascular pathology between 16 and 36 weeks' gestation were reviewed retrospectively. Twenty-two fetuses with pathology resulting in low- or high-CO states were also assessed for comparison. VTI was measured in both ventricular outflow tracts at the level of the semilunar valve, excluding a Doppler insonation angle of >30°. Heart rate, semilunar valve dimension, and VTI determined minute VTI and CO. Inter- and intrarater variability were evaluated in a random 10% subset.

RESULTS

Minute VTI and CO measurements were feasible in 67% to 89% of fetuses in this retrospective study. Minute VTI and CO increased with estimated fetal weight nonlinearly (R = 0.61-0.94). The mean inter- and intrarater variability for VTI, 6% and 5.7%, were significantly less than for CO, 25% and 23.7% (P < .001 for all).

CONCLUSIONS

Minute VTI is an easily measured, highly reproducible method of quantifying fetal ventricular systolic function. Variability in calculated CO from valve measurement differences is minimized by solely using VTI. Nomograms of minute VTI provide an efficient and precise assessment of fetal systolic function and may be used to track fetuses in disease states with low or high CO.

Fetal cardiac function at intrauterine transfusion assessed by automated analysis of color tissue Doppler recordings

BACKGROUND

Fetal anemia is associated with a hyperdynamic circulation and cardiac remodeling. Rapid intrauterine transfusion (IUT) of blood with high hematocrit and viscosity into the umbilical vein used to treat this condition can temporarily further affect fetal heart function. The aim of this study was to evaluate the short-term changes in fetal myocardial function caused by IUT using automated analysis of cine-loops of the fetal heart obtained by color tissue Doppler imaging (cTDI).

METHODS

Fetal echocardiography was performed before and after IUT. cTDI recordings were obtained in a four-chamber view and regions of interest were placed at the atrioventricular plane in the left ventricular (LV), right ventricular (RV) and septal walls. Myocardial velocities were analyzed by an automated analysis software to obtain peak myocardial velocities during atrial contraction (Am), ventricular ejection (Sm), rapid ventricular filling (Em) and Em/Am ratio was calculated. Myocardial velocities were converted to z-scores using published reference ranges. Delta z-scores (after minus before IUT) were calculated. Correlations were assessed between variables and hemoglobin before IUT.

RESULTS

Thirty-two fetuses underwent 70 IUTs. Fourteen were first time transfusions. In the LV and septal walls, all myocardial velocities were significantly increased compared to normal values, whereas in the RV only Sm was increased before IUT (z-scores 0.26-0.52). In first time IUTs, there was a negative correlation between LV Em (rho = - 0.61, p = 0.036) and LV Em/Am (rho = - 0.82, p = 0.001) z-scores and hemoglobin before IUT. The peak myocardial velocities that were increased before IUT decreased, whereas LV Em/Am increased significantly after IUT.

CONCLUSIONS

This study showed that peak myocardial velocities assessed by cTDI are increased in fetuses before IUT reflecting the physiology of hyperdynamic circulation. In these fetuses, the fetal heart is able to adapt and efficiently handle the volume load caused by IUT by altering its myocardial function.

Assessment of fetal right ventricular myocardial performance index changes following intrauterine transfusion

INTRODUCTION

Severe fetal anemia may cause cardiac ischemia, reduced contractility, and dysfunction. The purpose of our study is to evaluate right ventricular myocardial performance index (MPI) before and after intrauterine transfusion (IUT) in patients who underwent this procedure because of fetal anemia due to Rh-D alloimmunization.

MATERIALS AND METHODS

This prospective cohort study was conducted between January 2018 and June 2019 at Kanuni Sultan Suleyman Research and Training Hospital, Istanbul, Turkey. The pregnant women who were applied IUT because of fetal anemia due to Rh-D alloimmunization in our perinatology clinic were included in the study. Fetal right ventricular MPI before and 24 h after IUT were evaluated.

RESULTS

A total of 28 IUTs were performed in 17 pregnant women during the study period. The isovolumetric contraction time (ICT) and isovolumetric relaxation time (IRT) values measured before IUT, were found to be significantly longer compared to the ICT and IRT values measured after IUT. The MPI values measured after transfusion was found to be higher than before transfusion.

CONCLUSIONS

The fetal right ventricular MPI increases 24 h after IUT. This increase in the right ventricular MPI might be used as a marker for predicting adverse fetal outcomes following IUT.

Fetal anemia

The diagnosis and management of fetal anemia has been at the forefront of advances in the fields of fetal physiology, immunology, fetal imaging, and fetal therapy among others. Alloimmunization and parvovirus infection are the leading cause of fetal anemia in the United States. The middle cerebral artery peak systolic velocity (MCA-PSV) diagnoses fetal anemia. Its discovery is considered one of the most important achievements in fetal medicine. Accumulation of experience in recent years as well as refinement of surgical techniques have led to safer invasive procedures. It is expected that long term follow-up of affected pregnancies, continues to reflect all these improvements in care. It is also expected that treatment of other less common causes of fetal anemia becomes more frequently reported and that the management principles of fetal anemia are successfully applied to other fetal pathologies.

Fetal cardiac output in monochorionic twins

OBJECTIVES

To compare fetal cardiac output (CO) in donor and recipient twins of twin-twin transfusion syndrome (TTTS) pregnancies after laser therapy with that of monochorionic twins without TTTS and normal singletons.

METHODS

In a longitudinal, prospective study, we sonographically assessed fetal CO in donors (n = 10) and recipients (n = 10) with TTTS after fetoscopic laser therapy, in monochorionic twins without TTTS (n = 20) and in normal singleton pregnancies (n = 20). The fetal CO of TTTS twins was determined 1 day and 1 week after laser treatment, and from then on every 2-4 weeks until birth. Twins without TTTS were examined biweekly until birth. Singletons were examined twice, with an 8-week interval, at different gestational ages between 17 and 35 weeks.

RESULTS

Absolute CO increased exponentially with advancing gestational age (P < 0.0001), and was significantly related to fetal weight in all groups (P < 0.0001). The median CO/kg in donors after laser therapy, recipients after laser therapy and non-TTTS monochorionic twins was significantly higher than that in singletons (all P < 0.001). Median CO/kg in donors after laser therapy, recipients after laser therapy, and non-TTTS monochorionic twins was not significantly different between groups.

CONCLUSIONS

Monochorionic twins with TTTS have higher CO after laser therapy than normal singletons.

An Audit of Outcome in Intravascular Transfusions Using the Intrahepatic Portion of the Fetal Umbilical Vein Compared to Cordocentesis

INTRODUCTION

Maternal red cell alloimmunization is a potential cause of perinatal morbidity and mortality. The outcome of severe disease has been transformed by the use of in-utero and particularly, fetal intravascular transfusion. In the majority of instances this is performed by cordocentesis. However, this cohort study represents the experience in a large tertiary referral centre in performing fetal intravascular transfusions via the intrahepatic vein (IHV).

METHODS

Over an 8-year period, 1997-2004, 221 in-utero transfusions (IUT) were performed for rhesus disease in 66 pregnancies. 86% had severe fetal anaemia caused by anti-D, 10.6% by anti-Kell and 3.4% by anti-c. The median maternal age of the cohort was 31 years (range 19-43). The median gestation at initial IUT was 25 weeks (interquartile range (IQR) 23-29 weeks).

RESULTS

A median number of three IUT were performed in each fetus (IQR 2-5) with a median haemoglobin at first fetal blood sampling of 7.3 g% (IQR 4.6-8.8 g%) (73% < or =5 SD and 27% < or =2 SD). Of the total intravascular transfusions, 170 were performed via the IHV (71.7%), 33 via cordocentesis (13.9%) and 1 by intracardiac puncture (0.5%). There were 'transient' bradycardias complicating 4.1% of all transfusions and amniorrhexis following 1.4%. 92% of babies were live born at a median gestation of 34 weeks (range 21-38) with a birth weight centile of 50 (range 3-90). There was no significant difference in intravascular transfusion complication rate when the procedure was performed via the IHV (7.6%) as compared to cord root puncture (3.0%) (Fisher's exact test, p < 0.47).

CONCLUSION

IUT performed by fetal IHV puncture is safe and carries no excess morbidity when performed for severe rhesus disease.

[Contribution of fetal middle cerebral artery peak systolic velocity in the management of non-immune hydrops]

Hydrops fetalis is associated with a wide variety of fetal and maternal disorders. Among these disorders, cases with anemia may benefit from a specific treatment. The authors report on two cases of hydrops fetalis with increased middle cerebral artery peak systolic velocity and discussed the contribution of this finding in the management of fetuses with hydrops.

Fetal cardiac contractility before and after intrauterine transfusion

OBJECTIVE

To evaluate the effect of fetal anemia and intrauterine transfusion on ventricular shortening fraction.

METHODS

The end-diastolic and end-systolic transverse dimensions of the left and right ventricles were obtained using M-mode ultrasonography. The shortening fractions of both ventricles were calculated at three time points: before, immediately after and one day after intrauterine transfusion. The blood volume given at intrauterine transfusion was expressed as a percentage of estimated fetoplacental blood volume.

RESULTS

Complete measurements were obtained from 49 transfusions in 23 fetuses. Intrauterine transfusion was performed at a median gestational age of 31 (range, 19-35) weeks. Median hemoglobin concentration before and after intrauterine transfusion was 7.9 (range, 2.7-13.7) g/dL and 14.3 (range, 12.7-16.1) g/dL, respectively. Both left and right ventricular shortening fractions differed significantly between the three time points. Left ventricular shortening fraction decreased immediately after transfusion in 43 (88%) of the 49 procedures. Right ventricular shortening fraction decreased immediately after transfusion in 42 (86%) of the 49 procedures. At the first intrauterine transfusion, there was only a weak correlation between the decrease in shortening fraction of both ventricles and the transfused volume (left: R(2) = 0.15; P = 0.20/right: R(2) = 0.005; P = 0.81).

CONCLUSION

Transfusion significantly decreases the shortening fraction of both ventricles of the fetal heart. There is, however, little correlation between the decrease in shortening fraction and the volume of red cells given at intrauterine transfusion. Published by John Wiley & Sons, Ltd.

Red Blood Cell Alloimmunization in Pregnancy

Red blood cell (RBC) alloimmunization in pregnancy continues to occur despite the widespread use of both antenatal and postpartum Rhesus immune globulin (RhIG), due mainly to inadvertent omissions in administration as well as antenatal sensitization prior to RhIG given at 28 weeks' gestation. Additional instances are attributable to the lack of immune globulins to other RBC antigens. Evaluation of the alloimmunized pregnancy begins with the maternal titer. Once a critical value [32 for anti-Rh(D) and other irregular antibodies; 8 for anti-K and -k] is reached, fetal surveillance using serial Doppler ultrasound measurements of the peak velocity in the fetal middle cerebral artery (MCA) is standard. In the case of a heterozygous paternal phenotype, amniocentesis can be performed to detect the antigen-negative fetus that requires no further evaluation. MCA velocities greater than 1.5 multiples of the median necessitate cordocentesis, and if fetal anemia is detected, intrauterine transfusion therapy is initiated. A perinatal survival of greater than 85% with normal neurologic outcome is now expected. Future therapies will target specific immune manipulations in the pregnant patient.

The value of middle cerebral artery peak systolic velocity in the diagnosis of fetal anemia after intrauterine death of one monochorionic twin

OBJECTIVE

The purpose of this study was to assess the value of the fetal middle cerebral artery peak systolic velocity in the prediction of anemia within 24 hours of the death of one monochorionic twin in twin-to-twin-transfusion syndrome and to establish the correlation between middle cerebral artery peak systolic velocity and hemoglobin concentration in fetuses who are at risk for acute anemia.

STUDY DESIGN

Doppler examination of the middle cerebral artery peak systolic velocity was performed in 20 monochorionic survivors of pregnancies that were complicated by twin-to-twin-transfusion syndrome that occurred between 20 and 34 weeks of gestation. Doppler examination was performed before cordocentesis and after intrauterine transfusion when appropriate. Both hemoglobin concentration and middle cerebral artery peak systolic velocity were expressed in multiples of the median. Severe anemia was defined as hemoglobin concentration of <0.55 multiples of the median, and we used the cutoff point of 1.50 times the median values at any gestational age to calculate the sensitivity and specificity of middle cerebral artery peak systolic velocity in detecting moderate or severe anemia.

RESULTS

Fetal anemia was confirmed in 10 of 20 fetuses. We performed seven intrauterine transfusions. The sensitivity and specificity of middle cerebral artery peak systolic velocity in the prediction of severe fetal anemia were of 90%, with a false-negative rate of 10%. The correlation between peak systolic velocity and hemoglobin concentration both before and after transfusion was evaluated by regression analysis and was strongly significant.

CONCLUSION

In fetuses who are at risk of acute anemia, the measurement of middle cerebral artery peak systolic velocity was found to be a reliable noninvasive diagnostic tool and may be helpful in counseling and planning invasive assessment.

Middle cerebral artery Doppler for the prediction of fetal anaemia in cases without hydrops: a practical approach

The aim of this study was to assess the value of the middle cerebral artery (MCA) Doppler time-averaged mean velocity (TAMV) for the prediction of fetal anaemia in at-risk cases without ultrasound evidence of hydrops. The study included 35 pregnant women with non-hydropic fetuses and with known red cell antibodies, referred either because of a rapid increase in antibody levels or because of a previous history of a severely anaemic fetus or neonate. After full ultrasound examination of the fetus, MCA Doppler TAMV was measured and, if severe anaemia was suspected, fetal blood sampling by cordocentesis was performed with blood ready for intrauterine transfusion if necessary. Of the 35 fetuses, 28 were anaemic and 7 had a haemoglobin (Hb) value within the normal range. There was a strong negative correlation between the MCA Doppler TAMV and the Hb values (correlation coefficient r=-0.65, p<0.0001). The mean MCA Doppler TAMV (z score) for fetuses with normal Hb was 1.55+/-1.68, while that for the anaemic fetuses was 4.06+/-1.38, (p<0.001). The sensitivity of the increased MCA Doppler TAMV to predict fetal anaemia in these cases was 96.4% and the specificity was 71.4%. These data confirm that MCA Doppler TAMV is significantly correlated to fetal Hb. This non-invasive investigation can be reliable in predicting anaemia in cases in which the need to sample fetal blood is not certain, therefore delaying invasive testing until treatment is likely to be required.

Noninvasive diagnosis of anemia in hydrops fetalis with the use of middle cerebral artery Doppler velocity

OBJECTIVE

The purpose of this study was to assess the value of the middle cerebral artery time-averaged mean velocity for the detection of anemia as the cause of fetal hydrops.

STUDY DESIGN

We examined 17 pregnant women with fetuses with hydrops (with ascites as the main component of hydrops) and who were considered at risk for anemia because there was no obvious explanation for the hydrops on the initial scan. Assessment included the measurement of the middle cerebral artery time-averaged mean velocity by color flow Doppler scan, followed by fetal blood sampling for investigations that included fetal hemoglobin. We investigated the correlation between increased middle cerebral artery time-averaged mean velocity (>2 SDs for gestational age) and fetal anemia (<2 SDs for gestational age).

RESULTS

Eleven fetuses had anemia; 3 of the fetuses had red cell antibodies, and 6 of the fetuses had normal hemoglobin. There was a strong negative correlation between the middle cerebral artery time-averaged mean velocity and the hemoglobin values (r = -.9; P <.0001). The mean (z score) of middle cerebral artery time-averaged mean velocity for fetuses with normal hemoglobin was 1.1 +/- 0.81 and for the fetuses with anemia was 4.71 +/- 2.16 (P <.001). The sensitivity for the increased middle cerebral artery time-averaged mean velocity to predict fetal anemia was 91%, and the specificity was 100%.

CONCLUSION

The middle cerebral artery time-averaged mean velocity is significantly increased in cases of hydrops caused by anemia, including cases other than red-cell alloimmunization. These findings can be useful for counseling and treatment and allow the investigation of the cause of hydrops without awaiting blood for intrauterine transfusion in patients who are very unlikely to be anemic and often avoids 2 procedures in those patients who require transfusion. Larger studies are required to further confirm these findings.

Doppler ultrasound velocimetry for timing the second intrauterine transfusion in fetuses with anemia from red cell alloimmunization

OBJECTIVE

Middle cerebral artery peak systolic velocity has been successfully used for timing the first cordocentesis in fetuses who are at risk for anemia because of maternal red cell alloimmunization. The effects on Doppler velocimetry after the intrauterine transfusion of adult blood to these fetuses are unknown. The objective of this study was to assess the applicability of Doppler methods for the prediction of severe anemia in fetuses who had undergone 1 previous intrauterine transfusion.

STUDY DESIGN

Doppler examination of middle cerebral artery peak systolic velocity was performed before cordocentesis in 64 fetuses who had undergone 1 previous intrauterine transfusion. Timing of the second intrauterine transfusion was based on traditional criteria. Anemia was defined as mild (hemoglobin value between 0.84 and 0.65 multiples of the median), moderate (hemoglobin value <0.65-0.55 multiples of the median), and severe (hemoglobin value <0.55 multiples of the median). Receiver operator characteristic curves were created to select threshold values to identify the 3 degrees of anemia with a sensitivity of 100%.

RESULTS

Gestational age at the Doppler study ranged from 19 to 36 weeks. Forty-six fetuses (72%) were not or mildly anemic; 7 fetuses (11%) were moderately anemic, and 11 fetuses (17%) were severely anemic. Middle cerebral artery peak systolic velocity for the prediction of severe, moderate, and mild anemia at a sensitivity of 100% showed false-positive rates of 6%, 37%, and 70%, respectively.

CONCLUSION

In fetuses who have undergone 1 previous intrauterine transfusion because of maternal red cell alloimmunization, timing the second intrauterine transfusion can be determined noninvasively by Doppler ultrasonography on the basis of an increase in the peak velocity of systolic blood flow in the middle cerebral artery.

RhD isoimmunization and current management modalities

OBJECTIVE

To review the literature on current perspectives and treatment of RhD isoimmunization.

DATA SOURCES

A search was conducted on MEDLINE and CINAHL, and supplemental articles/ bulletins were obtained from cited references and the Web site of the American College of Obstetricians and Gynecologists. Recent texts also were reviewed. Key search words: isoimmunization, Rho (d) immune globulin, fetal erythroblastosis, intrauterine blood transfusions, alloimmunization.

STUDY SELECTION

Articles and comprehensive works from indexed journals in the English language relevant to key words and published after 1995 were evaluated. Historically relevant periodicals and texts were also reviewed and selected.

DATA EXTRACTION

Data were extracted and organized under the following headings: testing of the antepartum patient, antepartum treatment of isoimmunization, testing of the postpartum patient, anti-D immune globulin, antepartum anti-D immune globulin prophylaxis, other antepartum and obstetric indications for anti-D immune globulin administration, postpartum anti-D immune globulin prophylaxis, nursing implications, and future possibilities.

DATA SYNTHESIS

RhD isoimmunized pregnancies continue to contribute to worldwide perinatal and neonatal morbidity and mortality. This review describes the basic knowledge necessary to care for these pregnancies and the current management modalities.

CONCLUSIONS

The management options for RhD compromised gestations continue to evolve almost as quickly as technological advances are made. Multiple areas of research in this field have surfaced, and nurses can become valuable members of these research teams. The literature also indicates that with the available knowledge and resources, the current rate of RhD isoimmunization can be further decreased with closer adherence to proposed management guidelines by all health care professionals.

Splenic artery Doppler peak systolic velocity predicts severe fetal anemia in rhesus disease

OBJECTIVE

We sought to determine whether main splenic artery Doppler peak systolic velocity predicts severe anemia in the rhesus-alloimmunized fetus.

STUDY DESIGN

Splenic artery Doppler peak systolic velocity was obtained before cordocentesis in rhesus-alloimmunized fetuses. Normative values for mean peak systolic velocity based on gestational age were obtained cross-sectionally from a separate group of 144 normal fetuses. The peak systolic velocity values in the study group were expressed as multiples of the median for gestation, and threshold values were used as a screening test for severe anemia. The hemoglobin deficit was defined as mean hemoglobin for gestation minus measured hemoglobin. A hemoglobin deficit value of > or =5 g/dL was used to define severe anemia. We used the peak systolic velocity to screen for severe anemia in the overall study group and the subgroups with or without prior transfusions.

RESULTS

The study population consisted of 26 singleton nonhydropic fetuses in which cordocentesis and Doppler measurements were performed on a total of 55 occasions. The mean gestational age and standard deviation at cordocentesis was 29.6 +/- 4.0 weeks. Severe anemia was noted in 20% of fetal cord blood specimens obtained. On the basis of a receiver operating characteristic curve, a peak systolic velocity of > or =1.4 multiples of the median had a detection rate of 100%, with a false-positive rate of 20.8% in the subgroup with no prior transfusion (relative risk, 4.8; 95% confidence interval, 2.2-10.5). For peak systolic velocity threshold of > or =1.50 multiples of the median, corresponding values in the group with one prior transfusion were 80% and 12.5%, respectively (relative risk, 2.5; 95% confidence interval, 1.2-5.3). There was no risk of severe anemia with a peak systolic velocity below the median for gestation.

CONCLUSION

Fetal hydrops is rare, with a hemoglobin deficit of <5 g/dL. In the first such report the main splenic artery peak systolic velocity was noted to be a strong predictor of severe anemia. For the overall population, all such instances could be diagnosed while cordocentesis was performed 22.7% of the time. There is no risk of severe anemia with Doppler peak systolic velocities below the median for gestational age. The measurement is easily obtained and should be investigated as a clinical tool for minimizing the necessity for cordocentesis.

Noninvasive diagnosis by Doppler ultrasonography of fetal anemia due to maternal red-cell alloimmunization. Collaborative Group for Doppler Assessment of the Blood Velocity in Anemic Fetuses

BACKGROUND

Invasive techniques such as amniocentesis and cordocentesis are used for diagnosis and treatment in fetuses at risk for anemia due to maternal red-cell alloimmunization. The purpose of our study was to determine the value of noninvasive measurements of the velocity of blood flow in the fetal middle cerebral artery for the diagnosis of fetal anemia.

METHODS

We measured the hemoglobin concentration in blood obtained by cordocentesis and also the peak velocity of systolic blood flow in the middle cerebral artery in 111 fetuses at risk for anemia due to maternal red-cell alloimmunization. Peak systolic velocity was measured by Doppler velocimetry. To identify the fetuses with anemia, the hemoglobin values of those at risk were compared with the values in 265 normal fetuses.

RESULTS

Fetal hemoglobin concentrations increased with increasing gestational age in the 265 normal fetuses. Among the 111 fetuses at risk for anemia, 41 fetuses did not have anemia; 35 had mild anemia; 4 had moderate anemia; and 31, including 12 with hydrops, had severe anemia. The sensitivity of an increased peak velocity of systolic blood flow in the middle cerebral artery for the prediction of moderate or severe anemia was 100 percent either in the presence or in the absence of hydrops (95 percent confidence interval, 86 to 100 percent for the 23 fetuses without hydrops), with a false positive rate of 12 percent.

CONCLUSIONS

In fetuses without hydrops that are at risk because of maternal red-cell alloimmunization, moderate and severe anemia can be detected noninvasively by Doppler ultrasonography on the basis of an increase in the peak velocity of systolic blood flow in the middle cerebral artery.

Left ventricular hemodynamics in anemic fetal lambs

OBJECTIVE

To assess the left ventricular determinants of cardiac output in 12 chronically instrumented fetal lambs, six of which where made anemic.

METHODS

Twelve, singleton pregnant ewes were instrumented between 123-126 days gestation and chronic catheters placed in-situ. In six fetal lambs, isovolemic fetal anemia was induced (reducing the hematocrit from a mean of 35% to 20%). In a prospective study, absolute 'beat-to-beat' LV volumes and pressures were obtained (gestational age 131-134 days) using a conductance catheter method and a comparison made with non-anemic fetal lambs.

RESULTS

The group of anemic fetuses (n = 6) had a significantly reduced hematocrit as compared to the control group (37% decrease: mean difference--13.4%; P < 0.001). The arterial blood gases of the two groups were not statistically different, with the exception of the pO2 and oxygen content which were significantly lower in the anemic group (P < 0.05). There was no significant change in fetal heart rate, LV preload (as assessed by venous pressure, end-diastolic volume and pressure) or mean arterial pressure between the anemic and control groups. However, a 75% increase in LV stroke volume was observed in the anemic fetal lambs (P < 0.05), secondary to a 61% fall in LV afterload (P < 0.05). There was no significant change in inherent myocardial contractility of the LV, although this did increase to approach statistical significance in the anemic group (P = 0.056). The diastolic time interval was increased by 22% in the anemic fetus, possibly allowing prolonged LV filling time. The indices measuring LV relaxation (Tau and dP/dtmin) were not significantly different in either group.

CONCLUSIONS

This is the first study to report absolute left ventricular volumes in the anemic ovine fetus and the relationship of these data to LV pressure during the cardiac cycle. The model used produces a state of moderately severe, non-hydropic, isovolemic, fetal anemia consistent with those previously described. Although the anemic state was not prolonged, an observed increase in LV stroke volume (which is predominantly due to a decrease in afterload) has been described.

Fetal transfusion therapy

Rapid advances are occurring in the diagnosis and treatment of the fetus with a red blood cell or platelet cytopenia. Noninvasive methods of monitoring the alloimmunized pregnancy, invasive methods such as amniocentesis and cordocentesis, and intrauterine transfusion therapy of both red cells and platelets, are being further refined to allow the prompt recognition and treatment of fetal cytopenias. Specialized centers have now accrued a large experience in the management of the fetus severely affected by alloimmunization. Advances in ultrasound, blood banking techniques, and genetic engineering technology have spurred the most recent advances. The indications for diagnosis, timing and frequency of invasive procedures for treatment, and technical considerations regarding preparation of blood products and volume of transfusion, are outlined in this review. Polymerase chain reaction (PCR) determination of fetal Rh(D) genotype by chorionic villus sampling or amniocentesis in the first or second trimesters is a recent clinically useful advance. The advent of hematopoietic stem cell transplantation and the potential for gene therapy are exciting advances in the treatment and prevention of hematopoietic diseases, including, but not limited, to the fetal cytopenias.

Fetal and neonatal haemodilution associated with multiple placental chorioangioma: case report

A pregnancy with polyhydramnios and abnormal antepartum fetal heart rate pattern was found to have multiple placental haemangiomas. Multiple placental haemangiomas can give rise to fetal cardiac failure due to a hyperdynamic circulation or fetal anaemia either due to haemodilution or possibly destruction of blood cells in the chorioangioma. Whether fluid restriction with or without diuretics or blood transfusion is the correct form of treatment of neonatal cardiac failure in such a case is discussed.

Changes in hemorheology with fetal intravascular transfusion

OBJECTIVE

Our aim was to determine the changes in fetal hemorheologic parameters caused by fetal intravascular transfusion for alloimmune anemia.

STUDY DESIGN

Fetal blood samples were collected before and after 95 fetal transfusions in 31 women. Fetal hematocrit, whole-blood viscosity at a variety of shear rates, plasma viscosity, fetal fibrinogen, and fetal plasma proteins were measured.

RESULTS

Fetal whole-blood viscosity increased, sometimes massively, with transfusion. The rise in viscosity was principally dependent on the rise in hematocrit, with a linear rise in hematocrit producing a linear rise in the logarithm of whole-blood viscosity, but was also affected by the amount of adult plasma proteins present in the donor blood.

CONCLUSIONS

Rises in fetal whole-blood viscosity during transfusion can be minimized by using donor blood that has been serum depleted to a high hematocrit (> 90%) and by restricting the end hematocrit to 50% to 55%.

Umbilical venous pressure in normal, growth-retarded, and anemic fetuses

OBJECTIVE

Our purpose was to establish a reference range with gestation for umbilical venous blood pressure and to examine possible changes in intrauterine growth retardation and red blood cell isoimmunization.

STUDY DESIGN

Umbilical venous pressure was measured at cordocentesis in pregnancies complicated by intrauterine growth retardation (n = 20) and red blood cell isoimmunization (n = 61) both before and after intravascular fetal blood transfusion. The values were compared with a reference range that was constructed from the study of 111 pregnancies undergoing prenatal diagnosis at 18 to 40 weeks' gestation.

RESULTS

In the control group the mean umbilical venous pressure increased significantly with gestation. In the growth-retarded fetuses umbilical venous pressure was higher, normal, or decreased, and there was no significant association between umbilical venous pressure and either fetal size or degree of acidemia. In the pregnancies complicated by red blood cell isoimmunization umbilical venous pressure increased with anemia but decreased to normal in the most severely anemic and hydropic fetuses. After intravascular blood transfusion umbilical venous pressure in proportion to the improvement in fetal hemoglobin concentration.

CONCLUSION

Umbilical venous pressure is not the equivalent of central venous pressure but reflects both left and right heart function and placental resistance.