Sonographic markers of fetal α-thalassemia major

Fetal hemodynamic changes and mitochondrial dysfunction in myocardium and brain tissues in response to anemia: a lesson from hemoglobin Bart's disease

OBJECTIVE

Whether or not the effects of anemia in the early phase, while the fetuses attempts to increase cardiac output to meet oxygen requirement in peripheral organs, is detrimental to the fetal developing vital organs is little-known. The objective of this is to compare prenatal cardiovascular changes and post-abortal cellular damages in the myocardium as a pumping organ and the brain as a perfused organ between anemic fetuses (using fetal Hb Bart's disease as a study model) in pre-hydropic phase and non-anemic fetuses.

METHODS

Fetuses affected by Hb Bart's disease and non-anemic fetuses at 16-22 weeks were recruited to undergo comprehensive fetal echocardiography. Cord blood analysis was used to confirm the definite diagnosis of fetal Hb Bart's disease and normal fetuses. Fetal cardiac and brain tissues were collected shortly after pregnancy termination for the determination of oxidative stress and mitochondrial function, including mitochondrial ROS production and mitochondrial membrane changes.

RESULTS

A total of 18 fetuses affected by Hb Bart's disease and 13 non-anemic fetuses were recruited. The clinical characteristics of both groups were comparable. The affected fetuses showed a significant increase in cardiac dimensions, cardiac function, cardiac output and brain circulation without deteriorating cardiac contractility and preload. However, in the affected fetuses, mitochondrial dysfunction was clearly demonstrated in brain tissues and in the myocardium, as indicated by a significant increase in the membrane potential change (p-value < 0.001), and a significant increase in ROS production in brain tissues, with a trend to increase in myocardium. The findings indicated cellular damage in spite of good clinical compensation.

CONCLUSION

The new insight is that, in response to fetal anemia, fetal heart increases in size (dilatation) and function to increase cardiac output and blood flow velocity to provide adequate tissue perfusion, especially brain circulation. However, the myocardium and brain showed a significant increase in mitochondrial dysfunction, suggesting cellular damage secondary to anemic hypoxia. The compensatory increase in circulation could not completely prevent subtle brain and heart damage.

First and Second Level Haemoglobinopathies Diagnosis: Best Practices of the Italian Society of Thalassemia and Haemoglobinopathies (SITE)

The purpose of this best practice paper is to review the current recommendations for the identification and prenatal diagnosis of hemoglobinopathies. Methods: The management committee of SITE selected and gathered a multidisciplinary team in order to formulate recommendations based on the available scientific evidence integrated with the opinions of experts, with the purpose of supporting clinicians. Results: We provide recommendations for first level tests (complete blood count, hemoglobin separation and iron balance), second level tests (molecular diagnosis) and prenatal diagnosis. Five Italian experts in hemoglobinopathies were consulted regarding the orientation of prenatal diagnosis, and for each indication, the degree of agreement among the experts has been specified. Conclusions: Best practice recommendations are the final outcome of this translational research and allow transfer to daily clinical practice.

Comparison of the Performances of Middle Cerebral Artery Peak Systolic Velocity and Cardiothoracic Diameter Ratio in Predicting Fetal Anemia: Using Fetal Hemoglobin Bart's Disease as a Study Model

OBJECTIVE

The aim of the study was to compare the performances of cardiothoracic diameter ratio (CTR) and middle cerebral artery peak systolic velocity (MCA-PSV) in predicting fetal hemoglobin (Hb) Bart's disease and identify the best CTR cut-off for each gestational period.

METHODS

Pregnancies at risk of fetal Hb Bart's disease (gestational ages of 12-36 weeks) were prospectively recruited to undergo ultrasound examination. The measurements of CTR and MCA-PSV were performed and recorded before invasive diagnosis.

RESULTS

During the study period (2005-2019), a total of 1,717 pregnancies at risk of fetal Hb Bart's disease met the inclusion criteria and were available for analysis, including 329 (19.2%) fetuses with Hb Bart's disease. The mean gestational age at the time of diagnosis was 19.30 ± 5.6 weeks, ranging from 12 to 36 weeks. The overall performance of CTR Z-scores is superior to that of MCA-PSV multiple of median (MoM) values; area under curve of 0.866 versus 0.711, p value <0.001. The diagnostic indices of CTR and MCA-PSV are increased with gestational age. Based on receiver operating characteristic curves of CTR Z-scores, the best cut-off points of CTR at 12-14, 15-17, 18-20, 21-23, and ≥24 weeks are 0.48, 0.49, 0.50, 0.51, and 0.54, respectively. The best cut-off of MCA-PSV is 1.3 MoM, giving the best performance at 21-23 weeks with a sensitivity of 91.8% and specificity of 85.5%.

CONCLUSION

The performance of CTR is much better than MCA-PSV in predicting fetal anemia caused by Hb Bart's disease. Nevertheless, whether this can be reproduced in anemia due to other causes, like isoimmunization, is yet to be explored.

Performance of Fetal Cardiac Volume Derived from VOCAL (Virtual Organ Computer-Aided AnaLysis) in Predicting Hemoglobin (Hb) Bart's Disease

OBJECTIVE

To determine the performance of fetal cardiac volume (CV) in the detection of fetal Hb Bart's disease among fetuses at risk at 18-22 weeks of gestation and to compare the performance with those of cardiothoracic diameter ratio (CTR) and middle cerebral artery peak systolic velocity (MCA-PSV).

METHODS

Fetuses at risk of Hb Bart's disease between 18 and 22 weeks of gestation prospectively underwent echocardiography with acquisition of the volume datasets (VDS) of fetal heart, using 4D-cardiac STIC. Subsequently, off-line analysis was blindly performed to measure cardiac volume using the VOCAL technique.

RESULTS

A total of 502 fetuses at risk meeting the inclusion criteria were included in the analysis, consisting of 117 (23.3%) fetuses with Hb Bart's disease and 385 (76.7%) unaffected fetuses. The mean (±SD) gestational age at the time of ultrasound examination was 19.70 ± 1.3 weeks. In predicting fetal Hb Bart's disease, CV, using a cut-off Z-score of 1.7, had a sensitivity of 94.9% and specificity of 94.0%. The performance of CV was slightly better than that of CTR but very superior to that of MCA-PSV (areas under curve: 0.988, 0.974 and 0.862, respectively).

CONCLUSIONS

Fetal CV has a very high performance in predicting fetal Hb Bart's disease at mid-pregnancy, comparable with CTR and much better than MCA-PSV.

Ultrasound Features of Fetal Anemia Lessons From Hemoglobin Bart Disease

Insights gained from this review are as follows: (1) Ultrasound is highly effective in early detection of fetal hemoglobin (Hb) Bart disease. (2) The most sensitive parameters in predicting Hb Bart anemia appear to be the cardiac diameter-to-thoracic diameter ratio, middle cerebral artery peak systolic velocity, and placental thickness. (3) Several other ultrasound markers are helpful in increasing specificity, such as hepatosplenomegaly. (4) Hydrops fetalis is not a consequence of heart failure but rather of hypervolemia and high vascular permeability of fetuses, whereas heart failure is a very late consequence of a long-standing overworked heart. (5) Management guidelines for fetuses at risk of Hb Bart disease are proposed.

Foetal haemodynamic response to anaemia

This study aims to update new knowledge regarding foetal cardiovascular response to anaemia, using foetal haemoglobin Bart's disease as a study model. Original research articles, review articles, and guidelines were narratively reviewed and comprehensively validated. The main foetal cardiovascular changes in response to anaemia are consequences of hypervolaemia and increased cardiac output to meet tissue oxygen requirement. New challenging insights are as follows: (i) the earliest morphological change is an increase in cardiac size and remodelling of the sphericity (an increase in diameter more pronounced than that in long axis) followed by several markers, such as placentomegaly and hepatosplenomegaly. (ii) The earliest functional change is increased peak systolic velocity of the red blood cells because of low viscosity, especially in the middle cerebral artery. (iii) The foetal heart has very high reserve potentials to cope with anaemia: increasing workload without increased central venous pressure and increased myocardial performance without compromising shortening fraction. This hard‐working period with good performance lasts long, including most part of the second and third trimester. (iv) At the time cardiomegaly myocardial cellular damage has already occurred, in spite of good cardiac function. (v) Anaemic hydrops foetalis is mainly due to hypervolaemia, hypoalbuminaemia, and high vascular permeability, not heart failure. (vi) Foetal heart failure occurs only when the adaptive mechanism becomes exhausted or long after the development of anaemic hydrops foetalis. Heart failure is a very late result of a longstanding overworked heart. (vii) Ultrasound is highly effective in the detection of foetal response to anaemia. An increase in cardiac size and middle cerebral artery is very helpful in predicting the affected foetuses in pre‐hydropic phase. (viii) Theoretically, intrauterine treatment of anaemic hydrops results in satisfactory outcomes as long as cardiac function is normal, but intrauterine intervention should be strongly considered in pre‐hydropic phase because myocardial cell damage could have already occurred in this phase or early hydropic phase. Anaemic hydrops foetalis is not primarily caused by heart failure as commonly advocated, but it is rather a consequence of hypervolaemia, hypoalbuminaemia, and high vascular permeability while heart failure is a very late consequence of a longstanding overworked heart. New insights gained from this review may be useful to base clinical practice on which sonographic markers imply significant pathological changes, how ultrasound can be helpful in early detection of anaemic response, when intrauterine transfusion for anaemia due to non‐lethal causes should be administered, etc.

The best cutoff value of middle cerebral artery peak systolic velocity for the diagnosis of fetal homozygous alpha thalassemia-1 disease

OBJECTIVE

To determine the best cutoff value of middle cerebral artery peak systolic velocity (MCA-PSV) for the diagnosis of fetuses with homozygous alpha thalassemia-1 disease.

METHODS

Pregnancies at risk for fetal homozygous alpha thalassemia-1 disease at 18 to 22 weeks were recruited. MCA-PSV was measured before cordocentesis for hemoglobin typing and complete blood count. The performance of the MCA-PSV for identifying affected fetuses was evaluated using a best cutoff value derived from the receiver operating characteristic (ROC) curve.

RESULTS

Among 142 fetuses at risk, 46 (32.4%) fetuses were diagnosed as affected by homozygous alpha thalassemia-1 disease and were categorized as mild anemia (16.3%), moderate anemia (58.1%), and severe anemia (25.6%). With the best cutoff point of MCA-PSV > 1.30 multiples of the median (MoM) or >30.0 cm/s, the sensitivity for predicting fetal homozygous alpha thalassemia-1 was 100%.

CONCLUSIONS

MCA-PSV > 1.30 MoM is the best cutoff value for the diagnosis of all degrees of fetal anemia from homozygous alpha thalassemia-1 fetuses. Because of its simplicity for interpretation and high efficacy, a cutoff value of MCA-PSV > 30 cm/s can also be used as an alternative marker for fetal anemia screening during 18 to 22 weeks of gestation.

Invasive prenatal diagnosis of α-thalassemia to control Hb Bart's hydrops fetalis syndrome: 15 years of experience

PURPOSE

The aim of the present study was to report experiences with invasive prenatal diagnosis of α-thalassemia for the prevention of Hb Bart's hydrops fetalis syndrome in the Guangxi Zhuang Autonomous Region, China.

METHODS

Pregnant women and their partners who tested positive for α⁰-thalassemia or were diagnosed with HbH diseases were counseled and suggested to undergo a prenatal diagnostic procedure for α-thalassemia. Fetal material was obtained by chorionic villus sampling (CVS) between 9 and 13 weeks of gestation, by amniocentesis between 16 and 24 weeks of gestation and by cordocentesis after 24 weeks of gestation. The α⁰-thalassemia gene types were detected by gap polymerase chain reaction (Gap-PCR). All results were finally confirmed by DNA analysis after delivery or termination of pregnancy.

RESULTS

An invasive prenatal α-thalassemia diagnosis was performed in 3155 cases at risk for Hb Bart's hydrops fetalis syndrome at our hospital from 2002 to 2016. CVS was performed in 1559 cases (49.4%), amniocentesis in 1240 cases (39.3%) and cordocentesis in 356 cases (11.3%). In total, 786 fetuses were diagnosed as Hb Bart's hydrops fetalis syndrome. Among these cases, the α-thalassemia genotype was --^SEA/--^SEA in 784 cases and --^SEA/--^THAI in 2 cases. All affected pregnancies were terminated in time.

CONCLUSIONS

This extensive experience suggests that carrier screening, molecular diagnostics, genetic counselling, and prenatal diagnosis are effective measures to prevent Hb Bart's hydrops fetalis syndrome.

Fetal heart size measurements as new predictors of homozygous α-thalassemia-1 in mid-pregnancy

OBJECTIVE

To evaluate the efficacy of using fetal heart size measurements derived from axial echocardiography to predict homozygous α-thalassemia-1.

DESIGN

Prospective diagnostic study.

SETTING

The carrier rate of α-thalassemia-1 (-/αα) in China's Guangxi Zhuang Autonomous Region is approximately 15%. If both parents are carriers, the risk of homozygous α-thalassemia-1 in one pregnancy is 25%.

PATIENTS

Singleton mid-pregnancies at risk of homozygous α-thalassemia-1 were enrolled.

OUTCOME MEASURES

Fetal heart measurements, including heart diameter (HD), heart length (HL), heart circumference (HC), and heart area (HA), were measured. The z-scores for these heart parameters were then calculated separately based on previously constructed z-score models. Finally, the accuracy of these predictive variables was analyzed and compared to that achieved by cardiothoracic ratio (CTR) using a receiver operating characteristic (ROC) curves analysis.

RESULTS

A total of 214 singleton pregnancies were recruited. The discriminatory power of HA and HD z-scores was better (z-test P< .01) while that of HC and HL z-scores was comparable to (z-test P>.05) that of CTR. HD combined with HA z-scores had the highest sensitivity (100%), and the specificity of HD and/or HA z-scores was 100%.

CONCLUSION

Fetal heart size measurements are novel, effective and noninvasive predictors of homozygosity for α-thalassemia-1 in mid-pregnancy. The discriminatory power of HD and HA z-scores was better than while that of HC and HL z-scores was comparable to that of CTR. Further investigation is needed to understand the effectiveness of these predictors.

Role of Ultrasonographic Placental Thickness in Prediction of Fetal Outcome: A Prospective Indian Study

Background Information

Placenta is the connecting organ between the mother and the fetus. It supplies oxygen and all the necessary elements for the growth and development of the fetus. In normal pregnancy, the growth of the placenta remains concordant with the growth of the fetus. The sonographic assessment of placenta can give information about the nutritional status of the fetus. It is known that normal placental thickness approximately equals gestational age. It is historically documented that placental weight is one-fifth of the fetal weight and abnormally thin or thick placenta is associated with increased incidence of perinatal morbidity and mortality. However, there are very few studies correlating placental thickness with Neonatal outcome.

Objectives

To correlate ultrasonographic placental thickness at 32 and 36 weeks pregnancy with neonatal outcome. To propose placental thickness as a simple test for prediction of neonatal outcome.

Methods

Placental thickness at 32 and 36 weeks was measured by ultrasound, in 130 pregnant mothers with confirmed dates and uncomplicated singleton pregnancy. Placental thickness was categorized as normal (10th-95th percentile), thin (<10th percentile) and thick (>95th percentile) at each stage and was correlated with birth weight and neonatal outcome.

Results

Neonatal outcome was good in women with normal placental thickness (10th-95th percentile) at 32 and 36 weeks and was compromised in women with thin (<10th percentile) and thick (>95th percentile) placentae.

Conclusion

Placental thickness at 32 and 36 weeks corresponds well with gestational age and is a good prognostic factor in assessing neonatal outcome. Therefore, placental thickness should be measured in addition to biometric parameters in antenatal women undergoing ultrasound.

A Program on Noninvasive Prenatal Diagnosis of α-Thalassemia in Mainland China: A Cost-Benefit Analysis

The aim of the present study was to determine the cost effectiveness of a noninvasive prenatal diagnosis (PND) program for α-thalassemia (α-thal) using ultrasound scan. During a 5-year period, 1923 pregnancies at-risk for homozygous α(0)-thal were recruited into the noninvasive PND program. There were 1452 women who avoided invasive testing because of a normal ultrasound scan. The remaining 471 showed abnormal fetal ultrasonographic findings, and invasive testing was recommended. The overall cost of running the noninvasive PND program was US$213,383, while the cost of running the invasive program would have been US$554,810. The total savings were estimated at US$356,499 for women with an unaffected pregnancy with a net saving of US$246 per capita. This study demonstrated that it is cost effective to run a noninvasive PND program for α-thal in an area where the disease is prevalent, and therefore effectively avoiding an invasive test in unaffected pregnancies.

Prevention of Hb Bart's (γ4) Disease Associated with the - -(THAI) α(0)-Thalassemia Deletion in Mainland China

α-Thalassemia (α-thal) is a common inherited disease in southern China. The severest form is Hb Bart's (γ4) disease, in which the affected fetuses almost always die in utero or shortly after birth, and the mothers are at high risk for severe morbidity. The most common type of α(0)-thalassemia (α(0)-thal) in southern China is Southeast Asian (- -(SEA)) deletion. Occasionally, Hb Bart's disease, caused by a compound heterozygosity for the - -(SEA) and - -(THAI) α(0)-thal deletions, can also be encountered. In this study, we report our experience with the prevention of Hb Bart's disease associated with the - -(THAI) α(0)-thal deletion. A total of 385 couples at risk for Hb Bart's disease, including seven who tested positive for the - -(SEA) deletion in one partner and the - -(THAI) deletion in the other, were found. Different prenatal procedures were offered, depending on the gestational age at presentation. Sixty-six affected fetuses were diagnosed prenatally; among these, two cases of Hb Bart's disease were compound heterozygotes for the - -(SEA) and - -(THAI) deletions. All affected pregnancies were terminated in time. We also presented a diagnostic protocol for identification of α(0)-thal trait that can reduce the number of samples for detection of the - -(THAI) deletion.