Fetoscopy in the assessment of unexplained fetal hydrops

Nuchal Translucency and Congenital Heart Defects

Nuchal translucency comprises a temporary accumulation of fluid in the subcutaneous tissue on the back of a fetus's neck, which accompanies the crown-rump length and is observed through an ultrasound performed between 11 and 13 weeks + 6 days gestation. Nuchal translucency is considered to be above normal when values are higher than the 95th/99th percentile or equal to or higher than 2.5/3.5 mm. The first connection between increased nuchal translucency and the presence of congenital heart defects is described in the study of Hyett et al., who observed that they are directly proportional. Since that time, several studies have been conducted to understand if nuchal translucency measurements can be used for congenital heart defect screening in euploid fetuses. However, there is great variability in the estimated nuchal translucency cutoff values for congenital heart defect detection. The purpose of this review was to understand how increased nuchal translucency values and congenital heart defects are related and to identify which of these defects are more frequently associated with an increase in these values.

Additional first-trimester ultrasound markers

The first trimester (11-13 +6 weeks) ultrasound examination is useful for several reasons: determination of an accurate date of confinement, diagnostic purposes, and screening for fetal defects. Nuchal translucency measurement combined with maternal serum markers (free b-human chorionic gonadotropin and pregnancy-associated plasma protein A) is the mainstay of first-trimester screening for chromosomal defects. However, over the past decade additional ultrasound markers have been developed that improve the performance of this type of screening. The novel markers include evaluation of the nasal bone, fronto-maxillary angle measurement, and Doppler evaluations of the blood flow across the tricuspid valve and in the ductus venosus.

Alpha-thalassaemia

Alpha-thalassaemia is inherited as an autosomal recessive disorder characterised by a microcytic hypochromic anaemia, and a clinical phenotype varying from almost asymptomatic to a lethal haemolytic anaemia.

It is probably the most common monogenic gene disorder in the world and is especially frequent in Mediterranean countries, South-East Asia, Africa, the Middle East and in the Indian subcontinent. During the last few decades the incidence of alpha thalassaemia in North-European countries and Northern America has increased because of demographic changes. Compound heterozygotes and some homozygotes have a moderate to severe form of alpha thalassaemia called HbH disease. Hb Bart's hydrops foetalis is a lethal form in which no alpha-globin is synthesized. Alpha thalassaemia most frequently results from deletion of one or both alpha genes from the chromosome and can be classified according to its genotype/phenotype correlation. The normal complement of four functional alpha-globin genes may be decreased by 1, 2, 3 or all 4 copies of the genes, explaining the clinical variation and increasing severity of the disease. All affected individuals have a variable degree of anaemia (low Hb), reduced mean corpuscular haemoglobin (MCH/pg), reduced mean corpuscular volume (MCV/fl) and a normal/slightly reduced level of HbA₂. Molecular analysis is usually required to confirm the haematological observations (especially in silent alpha-thalassaemia and alpha-thalassaemia trait). The predominant features in HbH disease are anaemia with variable amounts of HbH (0.8-40%). The type of mutation influences the clinical severity of HbH disease. The distinguishing features of the haemoglobin Bart's hydrops foetalis syndrome are the presence of Hb Bart's and the total absence of HbF. The mode of transmission of alpha thalassaemia is autosomal recessive. Genetic counselling is offered to couples at risk for HbH disease or haemoglobin Bart's Hydrops Foetalis Syndrome. Carriers of alpha⁺- or alpha⁰-thalassaemia alleles generally do not need treatment. HbH patients may require intermittent transfusion therapy especially during intercurrent illness. Most pregnancies in which the foetus is known to have the haemoglobin Bart's hydrops foetalis syndrome are terminated due to the increased risk of both maternal and foetal morbidity.

First Trimester Ultrasound Screening: An Update

For many years, the main use of ultrasound in the first trimester of pregnancy was to confirm viability and to establish gestational age. Indeed, the crown-rump length measurement in the first trimester remains the most accurate method to estimate the gestational age even today. However, improvements in ultrasound equipment and improvement in our understanding of normal and abnormal fetal development allows us now to perform a much more complete first trimester fetal evaluation. This pertains not only to the diagnosis of fetal anomalies but also to screening for fetal defects. The combination of the nuchal translucency measurement and maternal serum biochemistries (free β-hCG and PAPP-A) has been shown to be an extremely efficient way to screen for fetal aneuploidy. The addition of other first trimester markers such as the nasal bone evaluation, frontomaxillary facial angle measurement, and Doppler evaluation of blood flow across the tricuspid valve and through the ductus venosus improves the screening performance even further by increasing the detection rates and decreasing the false positive rates. Several of the first trimester markers also are useful in screening for cardiac defects. Furthermore, significant nuchal translucency thickening has been associated with a variety of genetic and nongenetic syndromes. A recently described first trimester marker called the intracerebral translucency appears to hold great promise in screening for open spine defects. Finally, it appears that a first trimester evaluation (uterine artery Doppler and the measurement of certain biochemical markers in the maternal serum) significantly improves the assessment of the risk of preeclampsia.

Middle cerebral artery peak systolic velocity and ductus venosus velocity in the investigation of nonimmune hydrops

PURPOSE

This study was performed to investigate the cause of nonimmune hydrops fetalis by measuring the peak systolic velocity (PSV) in the middle cerebral artery (MCA) and velocity waveforms of the ductus venosus (DV) with Doppler.

METHODS

This cross-sectional study was done on 19 pregnancies referred to three university teaching hospitals for further investigation of nonimmune hydrops fetalis in 2007 and 2008. The MCA-PSV and DV velocity waveforms were recorded in all fetuses. Anemia was investigated in cases with MCA-PSV values greater than 1.50 MoM (multiple of the median). Cardiovascular causes and chromosomal abnormalities were investigated in fetuses with abnormal DV velocity.

RESULTS

Four of 19 fetuses had MCA-PSV values greater than 1.50 MoM. The causes of anemia were cytomegalovirus, parvovirus B19 infections, congenital heart disease, and Turner syndrome. Four cases had reversed flow in the DV; three of them had congenital heart disease on echocardiography; and one had a normal echocardiogram, but an abnormal karyotype was detected.

CONCLUSION

Assessment of the MCA-PSV and DV velocity waveforms during sonographic examination of fetuses with nonimmune hydrops fetalis may improve our knowledge about the etiology of this condition.

First trimester ultrasonography in screening and detection of fetal anomalies

An obstetrical ultrasound examination provides invaluable information regarding the fetus. Until the mid-1980s, ultrasound in the first trimester was limited to localization of the pregnancy, establishing viability, and accurate dating. With the advent of high-resolution ultrasound and transvaginal scanning, a significant amount of information about the fetus can be gained and provided to the patient at a very early stage in gestation. This article provides an overview of the role of first trimester (11-13 + 6 weeks' gestation) ultrasound in screening and diagnosis of fetal anomalies. The first trimester is an ideal time for screening for aneuploidy, primarily due to the advantages that nuchal translucency (NT) measurement provides. NT measurement is also useful in establishing the risk of congenital cardiac disorders and a number of genetic and non-genetic syndromes. Significant NT thickening is associated with an increase in perinatal morbidity and mortality. Potential mechanisms resulting in increased NT are discussed. A number of new ultrasound markers for fetal aneuploidy have been investigated over the past several years, some of which appear to improve the screening efficacy of early ultrasonography. The role of these is reviewed. A number of fetal anomalies can now be consistently diagnosed in the first trimester. Their appearance at this early gestational age is discussed as well. It is clear that, data obtained by first trimester ultrasound are useful in counseling expectant parents and in planning the appropriate follow-up.

Increased nuchal translucency with normal karyotype

Increased fetal nuchal translucency (NT) thickness between 11 and 14 weeks' gestation is a common phenotypic expression of chromosomal abnormalities, including trisomy 21. However, even in the absence of aneuploidy, nuchal thickening is clinically relevant because it is associated with an increase in adverse perinatal outcome caused by a variety of fetal malformations, dysplasias, deformations, dysruptions, and genetic syndromes. Once the presence of aneuploidy is ruled out, the risk of perinatal outcome dose not statistically increase until the nuchal translucency measurement reaches 3.5 mm or more (>99th percentile). This increase in risk occurs in an exponential fashion as the NT measurement increases. However, if the fetus survives until midgestation, and if a targeted ultrasound at 20 to 22 weeks fails to reveal any abnormalities, the risk of an adverse perinatal outcome and postnatal developmental delay is not statistically increased.

Fetal middle cerebral artery peak systolic velocity in the investigation of non-immune hydrops

OBJECTIVE

In some cases of non-immune hydrops there is congenital or acquired fetal anemia. The aim of this study was to investigate the potential value of fetal middle cerebral artery peak systolic velocity (MCA-PSV) in the assessment and management of non-immune hydrops due to anemia.

METHODS

Fetal MCA-PSV and fetal hemoglobin concentration, in blood obtained by cordocentesis, were measured in 16 singleton pregnancies referred to our unit for further investigations because of a diagnosis of non-immune hydrops fetalis. In all cases a detailed ultrasound examination demonstrated moderate or severe ascites, with or without skin edema, and pericardial or pleural effusions. Furthermore, there were no obvious malformations to account for the hydrops. In each fetus the measured MCA-PSV and hemoglobin concentration were expressed as delta values (the difference in SD from the normal mean for gestation). Regression analysis was used to determine the significance of the association between delta MCA-PSV and delta fetal hemoglobin concentration. In addition, we searched our database to identify the sonographic features and hemoglobin concentration of fetuses with congenital infection.

RESULTS

In the 16 cases of non-immune hydrops there were seven with parvovirus B19 infection, one each of alpha-thalassemia and primary cardiomyopathy and seven with no obvious explanation for the hydrops. There was a significant association between delta MCA-PSV and delta hemoglobin concentration (delta hemoglobin = (delta MCA-PSV + 0.1437)/-0.4154; R(2) = 0.7202; P < 0.0001). In 10 of the cases the fetal hemoglobin concentration was more than 4 SD below the normal mean for gestation and in all these cases the MCA-PSV was more than 2 SD above the normal mean for gestation. Our computer search identified an additional nine fetuses with parvovirus B19 infection and in all cases the predominant sonographic finding was ascites and the hemoglobin concentration was more than 4 SD below the normal mean. In contrast, only 3/14 fetuses with cytomegalovirus, toxoplasmosis, coxsackie B or Treponema infection had ascites and only 2/14 had a hemoglobin deficit of 4-6 SD.

CONCLUSION

In the management of non-immune hydrops, measurement of fetal MCA-PSV can help identify the subgroup with fetal anemia.

A new successful therapy for fetal chylothorax by intrapleural injection of maternal blood

We present two cases of fetal chylothorax and hydrops diagnosed at 20 weeks' gestation, both of which underwent successful intrauterine treatment. In Case 1, a transient, near total resolution began 2 weeks after an iatrogenic hemothorax following a second thoracocentesis performed at 24 + 6 weeks. Because of pleural fluid reaccumulation, a Cesarean section was performed at 36 weeks. The 3805-g female neonate was admitted to neonatal intensive care but was discharged 50 days later in a healthy condition. In Case 2, resolution occurred after a third thoracocentesis and a second pleural injection of maternal blood, performed at 26 weeks. A 2660-g female neonate was delivered vaginally at 38 weeks. The infant remained asymptomatic and was discharged aged 4 days. Our experience suggests a possible useful role of intrapleural blood injection for the treatment of fetal chylothorax.

Fetal and neonatal leukemia

The biological and clinical characteristics of perinatal leukemia differ significantly from those of leukemia in older children, and the prognosis is generally bleak. Once complete remission is achieved, neonates with acute myelocytic leukemia (AML) fare much better than those with acute lymphocytic leukemia (ALL). The results of this study suggest that age, sex, type of leukemia, and cytogenetic findings have a strong influence on outcome. Neonates, particularly females, with pre-B ALL have a much worse prognosis than neonates and older children with this disease. Transient leukemia in the Down syndrome neonate is associated with significant morbidity; close follow-up is recommended for at least the first 3 years of life because of the potential of developing acute leukemia, particularly AMKL (M7). The purpose of this review is to focus on the fetus and neonate in an attempt to determine the various ways leukemia differs clinically and morphologically from the disease occurring in older infants and children and to demonstrate that certain types of leukemia have a poor prognosis compared with those occurring in older children.

Increased fetal nuchal translucency thickness at 10-14 weeks: is screening for maternal-fetal infection necessary?

OBJECTIVE

To investigate the relation between increased fetal nuchal translucency thickness at 10-14 weeks of gestation and maternal-fetal infection.

DESIGN

Prospective study.

SETTING

Harris Birthright Research Centre for Fetal Medicine.

POPULATION

Four hundred and twenty-six chromosomally normal pregnancies with increased fetal nuchal translucency thickness at 10-14 weeks of gestation and 63 with 'unexplained' second or third trimester fetal nuchal oedema or hydrops.

METHODS

Maternal serum infection screening and investigations for fetal infection in those with evidence of recent maternal infection.

MAIN OUTCOME MEASURES

Maternal and fetal infection.

RESULTS

Evidence of recent maternal infection was present in six of the 426 pregnancies (1.4%) with increased fetal nuchal translucency thickness at 10-14 weeks, but in all cases a healthy infant was born with no evidence of infection. In contrast, 'unexplained' second or third-trimester fetal hydrops was associated with maternal infection in six of the pregnancies (9.5%) and in all cases there was evidence of fetal infection.

CONCLUSIONS

Maternal-fetal infection is one of the causes of second or third trimester nuchal oedema or fetal hydrops. In contrast, the presence of increased nuchal translucency in the first trimester is not a marker of either maternal or fetal infection.

Non-immune hydrops fetalis associated with impaired fetal movement: a case report and review

Non-immune hydrops fetalis (NIHF) is due to many different causes. Fetal hypomobility has been alluded to as a possible cause. We present a preterm fetus with NIHF secondary to fetal hypomobility. Fetal movements were undetected after the 20th week of gestation. The infant was born 8 weeks later and was edematous, had pleural effusions, and no spontaneous movements. He died on day four of life. Diffuse massive central nervous system (CNS) destruction found on post-mortem examination was thought to be the origin of the hypomobility. As all other causes of NIHF were eliminated, we propose that the NIHF in this infant was due to the hypomobility. This case then gives support to the assertion that fetal hypomobility is another cause of NIHF. The cause of the CNS catastrophy remains unelucidated.

Umbilical venous pressure in nonimmune hydrops fetalis: correlation with cardiac size

OBJECTIVES

Our objectives were to examine the relationship between umbilical venous pressure and cardiac size in nonimmune hydrops fetalis and to assess the role of cardiac failure in the pathogenesis of the disease.

STUDY DESIGN

Fourteen fetuses with nonimmune hydrops fetalis were investigated in a tertiary referral unit with high-resolution ultrasonography, echocardiography, and fetal blood sampling. Fetal heart size was assessed by measurement of the cardiothoracic ratio. Umbilical venous pressure was measured at the time of fetal blood sampling with a fluid-filled system.

RESULTS

The 10 fetuses with elevated umbilical venous pressures had significantly increased cardiothoracic ratios (p = 0.02). These fetuses also had ascites. Four other fetuses had normal-sized hearts, normal umbilical venous pressures, and no ascites. There was a linear relationship between cardiothoracic ratio and umbilical venous pressure (r = 0.75, p = 0.003).

CONCLUSION

Measurement of umbilical venous pressure validates cardiothoracic ratio as a noninvasive assessment of cardiac function in nonimmune hydrops.

Fetal nuchal translucency: ultrasound screening for chromosomal defects in first trimester of pregnancy

OBJECTIVE

To examine the significance of fetal nuchal translucency at 10-14 weeks' gestation in the prediction of abnormal fetal karyotype.

DESIGN

Prospective screening study.

SETTING

The Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London.

SUBJECTS

827 fetuses undergoing first trimester karyotyping by amniocentesis or chorionic villus sampling.

MAIN OUTCOME MEASURE

Incidence of chromosomal defects.

RESULTS

The incidence of chromosomal defects was 3% (28 of 827 cases). In the 51 (6%) fetuses with nuchal translucency 3-8 mm thick the incidence of chromosomal defects was 35% (18 cases). In contrast, only 10 of the remaining 776 (1%) fetuses were chromosomally abnormal.

CONCLUSION

Fetal nuchal translucency > or = 3 mm is a useful first trimester marker for fetal chromosomal abnormalities.

Non-immune hydrops fetalis

This article reviews the various aspects of non-immune hydrops fetalis, including the historical background, aetiology, clinical presentation, antenatal diagnosis and perinatal management, as well as presenting some data on cases of non-immune hydrops fetalis treated in the newly established Obstetrics Department of the Chinese University of Hong Kong at the Prince of Wales Hospital.

Hydrops revisited: literature review of 1,414 cases published in the 1980s

This paper reviews 47 series of hydrops fetalis (804 cases) and 610 individual cases published since 1980. From this large number of cases, guidelines are derived for prenatal diagnosis and management.

Bart's hydrops fetalis--clinical presentation and management--an analysis of 25 cases

Twenty-nine hydropic infants were born in the Kandang Kerbau Hospital between 1980 and 1985, during which there were 131,658 deliveries, giving an incidence of 1 in 4,540 total births. Twenty-five of these cases were confirmed to be due to homozygous alpha thalassaemia. No case of fetal hydrops due to Rh isoimmunization was detected. The mean age of the mothers was 28.86 +/- 4.05 years (+/- SD). Eight patients had delivered 1 hydropic baby previously while 1 had a history of 2 babies with hydrops fetalis; 92% of the patients had been followed antenatally while 8% were first seen when they were admitted in labour; 25% of the patients had anaemia, 52% had polyhydramnios, 20% developed hypertension and 64% had bilateral lower limb oedema. None of the patients had concomitant hypertension, generalized oedema and proteinuria. In 4 cases of recurrent hydrops, serial ultrasound scans were performed from early pregnancy but ultrasonic features of hydrops fetalis were only seen from 27 weeks' gestation. Spontaneous labour occurred in 75% of patients at a mean of 32.3 +/- 3.3 weeks (+/- SD). All delivered vaginally and only 1 patient required abdominal decompression. Four patients required Caesarean section, 2 for failure to progress after induction of labour, 1 for major placenta praevia and the fourth for fetal distress; in the last case, diagnosis of hydrops fetalis was only made after delivery of the baby. All the babies in the series died within one hour of delivery. Homozygous alpha thalassaemia is the commonest cause of hydrops fetalis in Singapore and is an invariably fatal condition. It is associated with an increased incidence of maternal anaemia, polyhydramnios and prematurity.

Protein S and C4b-binding protein in fetal and neonatal blood

The levels of protein C, free protein S, C4b-binding protein and the distribution of total protein S between a free form and a conjugated form with C4b-binding protein, were measured in fetuses between 15 and 35 weeks of gestation, in newborns and in maternal blood throughout pregnancy. Fetal and newborn umbilical blood samples were obtained by cordocentesis; in the case of newborns, immediately after delivery. C4b-binding protein was detected in five out of seven newborns and in only three out of 20 fetuses. The fetuses (21, 24, 29 weeks, respectively) whose blood contained C4b-binding protein (10%, 29%, 12% of adult level, respectively), did not survive: the possible cause of death for one was given as viral infection; all three were severely deformed. Only free protein S was detected in fetal blood and the mean value was 40%. By contrast, the mean levels of protein C in the fetuses increased from 11% to 15.5% of adult levels with advancing gestation. We conclude that the relatively high levels of free protein S in fetal blood may contribute to its non-coagulability and compensate for the low protein C levels.

Percutaneous ultrasound-guided fetal blood sampling in the management of nonimmune hydrops fetalis

Nonimmune hydrops fetalis can be caused by fetal chromosomal, hematologic, cardiac, or infectious conditions. A fetal blood sample obtained from percutaneous ultrasound-guided fetal blood sampling can offer vital information about the underlying cause of nonimmune hydrops fetalis, and perinatal management can be planned accordingly. Ten cases of nonimmune hydrops fetalis were investigated with percutaneous ultrasound-guided fetal blood sampling and subsequent fetal blood analysis. Nine were proved to be Bart's hemoglobin hydrops fetalis, with 78.2% to 99% of Bart's hemoglobin in the fetal blood. Terminations of pregnancy were undertaken immediately, resulting in a lowered maternal morbidity rate. Free cord loops or an intra-abdominal portion of the dilated umbilical vein can be used for percutaneous fetal blood sampling in nonimmune hydrops fetalis when the placental cord insertion is difficult to visualize. Percutaneous ultrasound-guided fetal blood sampling and subsequent fetal blood analysis will eventually play a key role in the management of the puzzling nonimmune hydrops fetalis if the safety of ultrasound-guided fetal blood sampling can be verified by further clinical studies.

Nonimmune hydrops fetalis: clinical experience and factors related to a poor outcome

Twenty-one cases of nonimmune hydrops fetalis diagnosed at the Medical College of Georgia during a 2-year period are presented. All fetuses satisfied strict diagnostic criteria and were evaluated according to a standard protocol. The corrected mortality rate was 95% with pulmonary hypoplasia being the most common cause of perinatal death. The mean gestational age at diagnosis was 24.8 weeks; in 57% of the cases the cause of nonimmune hydrops fetalis was identified. Fifteen fetuses had serial ultrasound assessment and in 19 cases postnatal evaluation was performed. Two factors that consistently conveyed a poor perinatal outcome were ultrasonographic evidence of malformation and/or the presence of persistent pleural effusions. A method for the quantification of fetal pleural effusions is presented and its clinical relevance is discussed.

Rapid karyotyping in non-lethal fetal malformations

Pure fetal blood samples were obtained fetoscopically, at 16-36 weeks' gestation, from 118 pregnancies complicated by ultrasonographically demonstrable fetal anomalies. Cytogenetic analysis of fetal lymphocytes yielded results within two to four days. Chromosomal abnormalities were found in 12 of 37 fetuses with non-haemolytic hydrops fetalis, 8 of 12 with exomphalos, 1 of 3 with duodenal atresia, 9 of 39 with obstructive uropathy, 1 of 3 with unilateral pleural effusion, 2 of 10 with severe growth retardation and oligohydramnios, 2 of 9 with isolated hydrocephalus, and 3 of 4 with choroid plexus cysts (of the last 4, 1 also had obstructive uropathy and 1 exomphalos). 3 fetuses with gastroschisis were cytogenetically normal. The results suggest that rapid fetal karyotyping is advisable in all cases of non-lethal or potentially correctable fetal malformations detected sonographically during the second or third trimester of pregnancy.

Normal blood cell values in the early mid-trimester fetus

Samples of pure fetal blood from 116 fetuses of 15-21 weeks' gestation were obtained by direct vision fetoscopy. Ninety nine of these fetuses, presumed to be haematologically normal, were suitable for analysis. The data obtained show that the erythropoietic system is evolving rapidly in this gestational age range. The myeloid series shows no significant increase or decrease in numbers apart from eosinophils and basophils which increase significantly with gestational age whereas the platelet count remains constant. The growing application of fetoscopic blood sampling to the prenatal diagnosis and management of fetal blood disorders renders mandatory a knowledge of normal fetal blood values.