Fetal splenic size in anemia due to Rh-alloimmunization

Diagnosis of severe fetal anemia based on perinatal outcomes: a comparative analysis of the current reference values

Objectives. To compare current criteria for severe fetal anemia diagnosis. Methodology. A cohort study analyzed 105 alloimmunized fetuses that underwent cordocentesis due to risk of anemia. Concordance among the diagnostic criteria for severe fetal anemia, hemoglobin deficit >7 g/dL, hemoglobin deficit ≥5 g/dL, and hemoglobin concentration <0.55 MoM, was analyzed using Cohen's Kappa index. Perinatal mortality, fetal hydrops, and fetal acidosis were used to discuss discordances. Results. There was fair concordance among the three criteria analyzed: 0.80 (Kappa index, IC 95%: 0.67 to 0.93) when comparing hemoglobin deficit >7.0 g/dL and hemoglobin concentration <0.55 MoM criteria, 0.63 (Kappa index, IC 95%: 0.47 to 0.69) when comparing hemoglobin deficit ≥5.0 g/dL and hemoglobin deficit >7.0 g/dL reference, and 0.77 (Kappa index, IC 95%: 0.64 to 0.90) when comparing hemoglobin deficit≥5.0 g/dL and hemoglobin concentration <0.55 MoM standards. Eighteen cases were classified differently depending on the criteria used. The cut-off point of hemoglobin deficit ≥5 g/dL was the best criterion to discriminate fetuses with poor perinatal outcome in our study. Conclusions. Relevant discordances in classification of severe fetal anemia were pointed out. Some criteria may underestimate the real gravity of fetal anemia.

[Fetal magnetic resonance imaging of thoracic and abdominal malformations]

CLINICAL/METHODICAL ISSUE

Diagnosis and differential diagnosis of fetal thoracic and abdominal malformations.

STANDARD RADIOLOGICAL METHODS

Ultrasound and magnetic resonance imaging (MRI).

METHODICAL INNOVATIONS

In cases of suspected pathologies based on fetal ultrasound MRI can be used for more detailed examinations and can be of assistance in the differential diagnostic process.

PERFORMANCE

Improved imaging of anatomical structures and of the composition of different tissues by the use of different MRI sequences.

ACHIEVEMENTS

Fetal MRI has become a part of clinical routine in thoracic and abdominal malformations and is the basis for scientific research in this field.

PRACTICAL RECOMMENDATIONS

In cases of thoracic or abdominal malformations fetal MRI provides important information additional to ultrasound to improve diagnostic accuracy, prognostic evaluation and surgical planning.

Noninvasive approach for the management of hemolytic disease of the fetus

Hemolytic disease of the fetus and newborn (HDFN) is due to maternal alloantibodies directed against paternally inherited antigens on fetal red cells, and it is still a problem in affected pregnancies despite the routine use of anti-D immunoglobulin during pregnancy and shortly after delivery. The current noninvasive management of HDFN starts with the determination of fetal RhD genotype by use of cell-free fetal DNA in maternal plasma. When the fetus is antigen positive, the follow-up is performed by Doppler ultrasonography for the detection of moderate or severe anemia on the basis of an increase peak velocity of systolic blood in the middle cerebral artery. Finally, if anemia is suspected, an invasive approach is required in order to perform an intrauterine blood transfusion, which should only be attempted when the fetus needs transfusion. This approach reduces the iatrogenic conversion of mild-to-severe disease, which occurred as a result of the previous invasive management, and prevents unnecessary administration of human-derived blood products. These changes represent one of the genuine successes of fetal therapy.

Splenic circumference at midpregnancy as a predictor of hemoglobin Bart's disease among fetuses at risk

OBJECTIVE

To determine the accuracy of splenic circumference in predicting hemoglobin (Hb) Bart's disease among fetuses at risk at midpregnancy.

MATERIALS AND METHODS

Women with singleton pregnancies with a fetal risk of Hb Bart's disease were enrolled in the study at 18-22 weeks of gestation. All underwent splenic circumference measurement before cordocentesis for fetal blood analysis. The final diagnosis used as a gold standard was based on fetal Hb typing using high-performance liquid chromatography.

RESULTS

Among all the pregnancies, the prevalence of Hb Bart's disease was 26.1% (87/334 fetuses). Twenty-four fetuses (27.6%) had some degree of hydropic changes. Notably, of these 24, 22 showed splenomegaly as well. When hydropic fetuses were excluded, the sensitivity, specificity, positive predictive value and negative predictive value of splenic circumference in identifying affected fetuses were 68.3, 83.0, 50.6 and 91.1%, respectively.

CONCLUSION

Splenic circumference measurement at midpregnancy may be helpful in distinguishing affected fetuses from those unaffected. Among couples at risk with normal splenic size, the risk of having an affected child is much lower, whereas the enlarged spleen places the pregnancy at a higher risk. This information may help couples decide on invasive diagnosis or a noninvasive approach.

Fetal anaemia: diagnosis and management

Fetal anaemia can by treated by in-utero therapy, which results in a significant improvement in perinatal outcome. The important causes of fetal anaemia are rhesus alloimmunisation, kell alloimmunisation and parvovirus infection. At-risk pregnancies require serial monitoring to ensure timely intervention with intrauterine transfusion. Non-invasive testing with middle cerebral artery Doppler is becoming the monitoring modality of choice.

Fetal abdominal magnetic resonance imaging

This review deals with the in vivo magnetic resonance imaging (MRI) appearance of the human fetal abdomen. Imaging findings are correlated with current knowledge of human fetal anatomy and physiology, which are crucial to understand and interpret fetal abdominal MRI scans. As fetal MRI covers a period of more than 20 weeks, which is characterized not only by organ growth, but also by changes and maturation of organ function, a different MR appearance of the fetal abdomen results. This not only applies to the fetal intestines, but also to the fetal liver, spleen, and adrenal glands. Choosing the appropriate sequences, various aspects of age-related and organ-specific function can be visualized with fetal MRI, as these are mirrored by changes in signal intensities. Knowledge of normal development is essential to delineate normal from pathological findings in the respective developmental stages.

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.

Condition-specific antepartum fetal testing

OBJECTIVE

The purpose of this study was to determine the best available antepartum fetal testing methods according to the underlying pathophysiologic condition.

STUDY DESIGN

We reviewed the current literature and our clinical experience with respect to condition-specific antepartum fetal testing.

RESULTS

The efficacy of most antepartum tests that we use today is not supported by randomized controlled clinical trials, but from observational nonrandomized studies and expert opinion (evidence levels II or III).

CONCLUSION

Based on the available evidence, the accuracy of a test depends on the underlying pathophysiologic condition. To improve accuracy, we must use condition-specific fetal testing.

Noninvasive tests to predict fetal anemia: a study comparing Doppler and ultrasound parameters

OBJECTIVE

This study was undertaken to compare test characteristics of ultrasound and Doppler parameters in the prediction of fetal anemia in alloimmunized pregnancies.

STUDY DESIGN

In a prospective cohort study, 16 nonhydropic fetuses with red blood cell alloimmunization were evaluated with ultrasound and Doppler imaging. Middle cerebral artery (MCA) peak systolic velocity, intrahepatic umbilical venous (IHUV) maximum velocity, liver length, and spleen perimeter were measured. Results before first fetal blood sampling (FBS) or delivery were analyzed. Fetal anemia was defined as hemoglobin deficit 5 SD or greater. Sensitivity and specificity were calculated.

RESULTS

Six fetuses were anemic and required intrauterine transfusion, and 10 were not severely anemic at birth. MCA Doppler imaging was the best predictor of fetal anemia (100%), followed by IHUV (83%). Sensitivity was low for spleen perimeter (66%) and liver length (33%).

CONCLUSION

Doppler evaluation of MCA peak systolic velocity is better than IHUV maximum velocity, liver, or spleen size in the prediction of fetal anemia in red blood cell alloimmunization.

Marked splenomegaly in fetal cytomegalovirus infection: detection supported by three-dimensional power Doppler ultrasound

An enlarged fetal spleen can be associated with fetal infection, anemia and different syndromes but its prenatal diagnosis is rare. We report on a diagnosis of splenomegaly at 32 weeks' gestation in a fetus which was found to be affected by cytomegalovirus infection. An enlarged spleen was suspected when the stomach was found to be displaced anteriorly and medially and the diagnosis was supported on visualization of the splenic vessels by color and three-dimensional power Doppler ultrasound. The patient had been referred because of fetal growth restriction and intracerebral anomalies and the additional finding of splenomegaly was highly suspicious for cytomegalovirus infection. This was confirmed by positive maternal serology and by neonatal virus excretion in urine. Retrospectively, examination of stored blood samples from 9 and 23 weeks' gestation revealed an early cytomegalovirus infection. Antenatal and neonatal magnetic resonance imaging examinations showed microcephaly, lissencephaly and the presence of microcalcifications. At the age of 9 months, the child suffers from severe neurological impairment and blindness due to severe optical atrophy. This case emphasizes that color Doppler and three-dimensional power Doppler ultrasound can facilitate the antenatal diagnosis of splenomegaly and can help to delineate the spleen from the similar-looking neighboring liver.

Prediction of fetal anaemia

The perinatal outcome of the anaemic fetus has dramatically improved over the last 20 years, as a result of early recognition of the problem and treatment by intrauterine transfusion. Traditionally assessment of the anaemic fetus relied on obstetric history and maternal antibody titre, which proved to be inadequate tests to accurately predict fetal condition. More recently, invasive testing with techniques such as amniocentesis and cordocentesis have allowed a more accurate evaluation of the degree of anaemia, while at the same time enabling transfusion to take place. Such techniques are not without danger, with perinatal loss and fetomaternal haemorrhage being significant risks. The clinical community has therefore sought to find accurate, non-invasive methods for assessing the degree of fetal anaemia, thereby reducing the number of unnecessary invasive procedures, while at the same time providing more precise data on the quantity and timing of the transfusion. Recent publications focusing on the diagnosis and management (including plasmapheresis, immunoglobulins and intrauterine transfusion) of fetal anaemia will be discussed.

Invasive versus non-invasive testing in red-cell alloimmunized pregnancies

Amniocentesis for amniotic fluid bilirubin levels is the most widely used test to predict the severity of fetal disease in red-cell alloimmunization. Many textbooks and guidelines recommend serial amniocentesis to monitor these pregnancies. However, the reliability of amniotic fluid bilirubin measurements has been questioned. Two strategies have been proposed by investigators. Some advocate liberal or primary use of fetal blood sampling, while others promote the use of non-invasive ultrasonography and Doppler. The purpose of this literature review is to examine the usefulness of amniocentesis, ultrasonography and Doppler to predict the degree of fetal hemolytic anemia. The evidence suggests that amniotic fluid bilirubin measurements are of limited value in the second trimester. Furthermore, critical appraisal of the very few prospective studies is hampered by limitations in design or insufficient data given by the authors. Many ultrasound and Doppler parameters have been proposed as useful indicators of fetal anemia. The most promising of these methods are Doppler assessment of umbilical venous and middle cerebral artery flow velocities. We speculate that the accuracy of these non-invasive tests may be good enough to incorporate them in management protocols, possibly replacing amniocentesis. Well-designed prospective studies are needed to prove this hypothesis.

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.

Sonographic methods to detect fetal anemia in red blood cell alloimmunization

Published reports, case studies, and articles from the English language regarding ultrasonographic detection of fetal anemia in red blood cell alloimmunization were obtained from a MEDLINE search from 1966 to November 1999 using the keywords Rh disease, hemolytic disease of the newborn, ultrasound, and Doppler flow studies and combinations thereof. All articles were cross-referenced. Ultrasound techniques including early findings associated with immune hydrops fetalis, multiple morphologic ultrasound markers, and Doppler flow studies that have been used to detect fetal anemia are reviewed and critically evaluated. Noninvasive sonographic techniques may reduce the number of invasive procedures that traditionally are used to follow fetuses at risk for anemia and decrease the associated risks from these procedures.

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.