Normal fetal cardiac anatomy–a basis for the echocardiographic detection of abnormalities

Real-time examination of the fetal heart in 350 pregnancies has allowed a composite picture of normal fetal cardiac anatomy to be established and echocardiographic interpretation has been confirmed by anatomical studies. Two echocardiographic sections are readily obtainable and are suggested as applicable to routine scanning but the specialist nature of interpreting abnormalities is stressed. Six abnormalities have been suspected during the study and five confirmed anatomically or at cardiac catheterization. In view of the low incidence of congenital heart disease in a normal obstetric population, high risk groups should perhaps be selected for cardiac scanning at the present time. These include mothers of previously affected babies, diabetic mothers and certain abnormalities of pregnancy. Fetal ascites is particularly important, being present in three of the four proven cases of cardiac abnormality.     

Fetal behaviour in growth retardation: Its relationship to fetal blood flow

The fetal behaviour of asymmetrical growth retarded fetuses was compared with that of a control group of healthy fetuses. Fetuses underwent simultaneous cardiotocographic and echographic examinations for two consecutive hours at 36–38 weeks of gestation. The distribution of gross fetal body movements, fetal breathing movements and fetal eye movements was analysed during the different fetal heart rate patterns. Furthermore, the incidence and organization of fetal behavioural states was investigated. The degree of vascular peripheral resistance was also evaluated by means of pulsed doppler ultrasonic equipmznt. Growth retarded fetuses were divided into two groups on the basis of the presence or absence of end diastolic flow in the fetal thoracic descending aorta. Growth retarded fetuses showed a delay in the integration of behavioural patterns and a lower coincidence of behavioural states. These findings are particularly evident in the fetuses with a severe increase of peripheral vascular resistance (absence of end diastolic flow in descending aorta). Thus, we suggest that a delay in central nervous system development is present in asymmetrical growth retarded fetuses and that there is a possible relationship of this delay to the degree of peripheral vascular resistance.     

The fetal behavioural states: An ultrasonic study

In order to accurately detect the fetal behavioural state, we simultaneously measured fetal heart rate and multiple fetal activities in 27 healthy pregnant women at 38 to 40 weeks of gestation. We ultrasonically identified gross body movements, breathing movements and micturition. Analysis of fetal heart rate allowed us to distinguish two different patterns of fetal behaviour: active and quiet phases. The frequency distribution of the analysed fetal events was significantly different in these two phases. These data suggest that a complete biophysical profile of the fetus is effective in differentiating behavioural states and may improve the predictive accuracy of fetal heart rate analysis alone.     

The development of fetal behavioural states: A longitudinal study

In order to evaluate the development of fetal behavioural states a longitudinal study was performed on 35 healthy fetuses during the last trimester of pregnancy. Fetal heart rate (FHR), gross fetal body movements (FM), fetal eye movements (FEM), fetal breathing movements (FBM) and micturition were simultaneously studied at two-week intervals from 28 weeks gestation onwards. Well-defined fetal behavioural states were observed only after 36 weeks gestation. Between 28 and 36 weeks the quiet-activity cycle of FHR was always detected and some fetal biophysical activites seemed to become related around this cycle.     

Prenatal echocardiographic diagnosis of right atrial isomerism

A prenatal diagnosis of right atrial isomerism is often inferred through the recognition of a constellation of cardiac anomalies on the four-chamber view or by the detection of visceral heterotaxy and asplenia. However, the actual occurrence of discordance between the arrangement of the atria and thoracic and abdominal organs makes the identification of the morphology of both atrial appendages the only reliable way to make a final diagnosis of atrial isomerism. Three cases of right atrial isomerism with visceral heterotaxy and a complex cardiac defect, diagnosed in utero by cross-sectional and colour flow Doppler echocardiography, are reported. In all the patients, the right atrial isomerism was associated with an atrioventricular septal defect, a single aortic outlet from the right ventricle, and total anomalous venous return. The diagnosis of right atrial isomerism, always confirmed by neonatal re-evaluation and/or by post-mortem examination, was made through identifying two pyramidal atrial appendages in an echocardiographic transverse plane at the level of the atria and of the origin of the great arteries. This report demonstrates that a final intrauterine diagnosis of atrial isomerism is possible, whatever the visceral situs is.     

Prenatal measurement of the fetal cerebellum and cisterna cerebellomedullaris by ultrasound

The fetal cerebellum can be visualized with ultrasound throughout the second trimester. We describe a technique for measuring the transverse and anteroposterior cerebellar diameters and the measurement of the cisterna magna in the same plane between 14 and 32 weeks gestation. Nomograms for these measurements against gestational age showed good correlation, and narrow confidence limits for the transverse cerebellar diameter. The transverse cerebellar diameter was also measured directly in 79 fetuses after mid-trimester abortion and the measurements obtained were compared with the ultrasound TCD nomogram. Good correlation, was obtained between the post mortem measurements and the ultrasound TCD nomogram. Routine use of these measurements and nomograms should prove valuable in the diagnosis of congenital abnormality of the posterior fossa and may also be of use in assessing the effect of severe intrauterine growth retardation and other insults on cerebellar growth and development. The narrow confidence limits obtained with the TCD nomogram should enable it to be used with confidence in clinical practice.     

Failure to detect fetal obstructive uropathy by second trimester ultrasound

The prenatal diagnosis, management and outcome of an hereditary obstructive uropathy is presented. Serial ultrasonic assessment of the fetal urinary tract was carried out from the early second trimester onward. Slight bilateral hydronephrosis as a first sign of obstructive uropathy was only established as late as 30 weeks of gestation. On the basis of weekly ultrasound scans, a conservative approach was adopted. In view of fetal maturity, labour was induced at 36 weeks resulting in the vaginal delivery of a male infant with moderate bilateral hydronephrosis. Neonatally, anuria developed due to bilateral obstruction of the ureters as a result of increasing bladder wall hypertrophy due to urethral valves. A bilateral uretero-cutaneostomy was carried out. The infant so far develops normally, and renal function is normal for age. Women at risk for fetal obstructive uropathy should have ultrasonic monitoring throughout pregnancy.     

Computer-assisted analysis of fetal behavioural states

A computerized system which simultaneously acquires and quantifies several ultrasonically detected fetal activities, including gross body movements, breathing movements, and eye movements, was developed in order to obtain additional quantitative data on fetal behaviour. Movements were automatically related to fetal heart rate allowing computation of their mean incidence, duration, lag time and percentage time spent moving during different heart rate patterns. The incidence of various behavioural states was also calculated. The study of 15 healthy fetuses near term revealed the existence of statistically significant differences in these parameters between low and high variability patterns of fetal heart rate suggesting a quantitative modulation of fetal movements by behavioural states.     

Testosterone levels in midtrimester maternal and fetal plasma and amniotic fluid

Testosterone was measured in maternal plasma (58 samples), amniotic fluid (71 samples) and fetal plasma (55 samples) in 79 patients between 15 and 23 weeks' gestation. Maternal plasma testosterone levels were unrelated to fetal sex. Amniotic fluid testosterone was significantly higher in male than female fetuses but did not reliably predict fetal sex. A correct diagnosis of fetal sex was made by testosterone assay of pure fetal plasma in 39 out of 40 males and in 15 out of 15 females using 1.70 nmol/1 as the cut-off value. This investigation is not the method of choice for routine fetal sexing but may be of value in fetuses suspected of having certain endocrine disorders.     

Umbilical and uterine flow velocity waveforms in pregnancies complicated by major fetal anomalies

A continuous wave Doppler unit was used to obtain umbilical and uterine artery flow velocity waveforms in pregnancies complicated by a major fetal abnormality. A total of 139 examinations were performed on 32 women between 26 to 41 weeks' gestation, and the records were reviewed to determine the changes associated with fetal malformation. The systolic/diastolic (A/B) ratio was used as an index of blood flow resistance in the umbilical artery and the systolic minus diastolic divided by systolic (A–B)/A for the branches of the uterine artery. Seventeen out of 32 patients showed high systolic/diastolic ratio in waveforms taken from the umbilical artery. In 30 out of 32 patients the uterine artery waveform was normal (in two patients the results were equivocal). It appears that a fetal mechanism may determine the changes in the umbilical placental circulation resulting in an umbilical artery pattern of high flow resistance in more than half of the patients with congenital anomalies.     

Visualization of fetal intra-abdominal organs in second-trimester severe oligohydramnios by intraperitoneal infusion

Fetal intraperitoneal infusion of saline was performed in two patients with severe oligohydramnios at 24 and 25 weeks' gestation in order to enhance visualization of intra-abdominal organs. Renal agenesis was easily diagnosed. The technique can be considered as an alternative to artificial instillation of amniotic fluid in the differential diagnosis of conditions associated with severe oligohydramnios.     

Intrauterine manometry: Technique and application to fetal pathology

A technique is described for measuring pressure within the amniotic cavity and within fetal vessels and/or body compartments. Two saline-filled catheters were connected at one end to needles inserted during indicated invasive procedures and at the other to silicon strain gauge transducers. In 36 pregnancies with normal liquor volume, stable intra-amniotic pressure (IAP, range 1–14 mmHg) increased with gestation (r=0·48, p<0·01). In pregnancies complicated by severe oligohydramnios, IAP was ≤ 1 mm Hg and rose to normal levels with saline amnioinfusion. Raised IAP (range 17–26 mm Hg), found in pregnancies with gross polyhydramnios, fell with drainage of amniotic fluid. Subtraction manometry was used to determine supra-amniotic pressure within the intervillus space, umbilical vein, umbilical artery, abdominal and thoracic cavities, and the urinary tract in normal and/or pathological fetuses. Low intravesical and intrapelvicalyceal pressures (median 6·5, range 2–10 mmHg) were noted in fetuses with obstructive uropathies. Intrauterine subtraction manometry appears to be a useful tool in the understanding of fetal pathophysiology and may be of clinical benefit in the therapeutic drainage and infusion of amniotic fluid and in the assessment of certain fetal disease states.     

Prenatal confirmation of trisomy 12 mosaicism by fetal skin biopsy

Trisomy 12 mosaicism diagnosed at 16 weeks' amniocentesis in a 42-year-old woman was not confirmed at 18 weeks' gestational age in amniotic fluid or fetal blood. Fetal skin biopsy performed at the same time did, however, allow the detection of trisomy 12 in 1 of 14 fibroblasts analysed. Fetal skin biopsy can be included within the diagnostic procedures to be performed when a level III mosaicism is found in the amniotic fluid.     

A possible prenatal evaluation of renal function by amino acid analysis on fetal urine

Intrauterine treatment of 4 fetuses with urethral obstruction was attempted in the third trimester of pregnancy. The fetuses displayed varying sonographic findings including pyelectasis, caliectasis, hydroureter, bladder dilatation, ascites, hydrops, missing kidneys and oligohydramnios. Ultrasonically guided aspiration from the dilated structures was carried out to relieve pressure on the kidney parenchyme and to collect fluid samples for diagnostic purposes. Amino acid concentrations in the fetal urine showed a pattern similar to plasma in 2 fetuses, a pattern almost like urine in 1 fetus and an intermediate pattern in the 4th fetus. Only the fetus with normal amino acid concentrations in the urine survived: the other 3 died in uremia shortly after birth. In 3 cases cells from the aspirated urine were cultured and used for chromosome analysis. The cell cultures grew fast and karyotyping was possible within 1 week. In 2 fetuses an intrauterine catheter was inserted to drain the kidney permanently into the amniotic cavity. In the first case the catheter was displaced to the fetal abdomen after some days of successful drainage. In the second case the catheter tore the placenta, and the child had to be delivered immediately.     

The concurrence of fetal supraventricular tachycardia and obstruction of the foramen ovale

Fetal supraventricular tachycardia (FSVT) is a cardiac arrhythmia that bears a high mortality rate. In the majority of cases no morphological anomalies are found and death is caused by congestive heart failure. This report presents two cases of FSVT in which cross sectional echocardiography revealed obstruction of the foramen ovale with dilatation of the right heart without structural cardiac anomalies. After birth sinus rhythm re-established under digitalis medication in both cases. The association between premature obstruction of the foramen ovale and unexplained intrauterine death in the third trimester of gestation is suggested.     

Sonographic demonstration of fetal sacrococcygeal teratoma

Six cases of sonographically diagnosed fetal sacrococcygeal teratoma (SCT) are presented and illustrate the variable features of fetal SCT. The sonographic findings assisted the parents and perinatal team in making decisions, and in two of the cases the children survived after elective Cesarean section and prompt neonatal resection of the tumors. None of the patients showed signs of malignant degeneration of the teratoma or metastases. Fetal SCT no longer should be considered a uniformly fatal condition. The literature on sacrococcygeal teratoma detected after birth indicates that the mortality rate is correlated with the degree of extension of the tumor. Therefore, the classification of sonographically diagnosed fetal SCT according to its size and position is important for decisions regarding pregnancy management.     

Prenatal diagnosis of carbamoyl-phosphate synthetase deficiency by fetal liver biopsy

In a pregnancy at risk for carbamoyl-phosphate synthetase (CPS) deficiency, prenatal diagnosis was attempted by fetal liver biopsy, performed at 18 weeks of gestation. CPS activity was absent and the diagnosis was confirmed after termination of the pregnancy. The technique employed for fetal liver biopsy is described together with an evaluation of its possible role in prenatal diagnosis.     

Doppler echocardiographic diagnosis of intrauterine closure of the ductus arteriosus

A case of in utero closure of the ductus arteriosus was detected by Doppler echocardio-graphy at 31 weeks of gestation. It presented as a non-hydropic distressed fetus with ultrasound detection of tricuspid regurgitation. Pulsed Doppler ultrasound showed markedly decreased blood flow through the tricuspid and pulmonary valves and absent blood flow at the ductus arteriosus. These, as well as the resultant increased right-to-left shunting across the foramen ovale, were reaffirmed by colour flow mapping.     

Cardiotocographic and sonographic findings in two cases of antenatally diagnosed intrauterine fetal brain death

Intrauterine fetal brain death is a rare cause of a fixed fetal heart rate pattern. Seven cases have been previously reported in the literature, but only two of them were diagnosed prenatally and all the newborns died soon after delivery. Two additional cases of antepartum diagnosis of intrauterine fetal brain death, managed expectantly, are reported. We had the unique opportunity to document progressive sonographic cerebral changes during the follow-up period, following the neurological event, while the fetus continued life and growth in utero. The cardiographic and sonographic findings suggesting intrauterine fetal brain death were a prolonged fixed fetal heart rate, even following a vibroacoustic and contraction stress test; an atonic fetus without breathing and body movement; and the appearance of hydramnios and the development of ventriculomegaly.     

Measurement of the fetal mandible—feasibility and construction of a centile chart

The prenatal diagnosis of micrognathia is usually based on a subjective impression of the size of the jaw when examining the fetal profile. We have constructed a centile chart for mandibular length between 12 and 27 post-menstrual weeks in a cross-sectional study of 184 fetuses. The application of this chart in clinical practice may permit a more objective diagnosis of micrognathia in the prenatal period.