Quality Requirements for the early Fetal Ultrasound Assessment at 11-13+6 Weeks of Gestation (DEGUM Levels II and III).

The early fetal ultrasound assessment at 11 - 13(+6) weeks of gestation remains the cornerstone of care despite the progress in diagnosing fetal chromosomal defects using cell-free fetal DNA (cffDNA) from the maternal circulation. The measurement of nuchal translucency (NT) allows the risk calculation for the fetal trisomies 21, 18 and 13 but also gives information on those fetal chromosomal defects which are at present unable to be detected using cffDNA. Nuchal translucency is the only auditable parameter at 11 - 13(+6) weeks and gives thus information on the quality of the first trimester anomaly scan. In addition it gives indirect information on the risks for fetal defects and for cardiac anomalies. Also the chances for a healthy live baby can be estimated. As experience with first trimester anomaly scanning increases, and the resolution of the ultrasound equipment has increased substantially, more and more details of the fetal anatomy become accessible at the first trimester scan. Therefore fetal anatomical defects and complex anomalies have become amenable to examination in the first trimester. This guideline describes compulsory and optional parameters for investigation at the first trimester scan and outlines a structured method of examining a first trimester fetus at 11 - 13(+6) weeks of gestation.

Assessment of intracranial translucency (IT) in the detection of spina bifida at the 11-13-week scan.

OBJECTIVE: Prenatal diagnosis of open spina bifida is carried out by ultrasound examination in the second trimester of pregnancy. The diagnosis is suspected by the presence of a 'lemon-shaped' head and a 'banana-shaped' cerebellum, thought to be consequences of caudal displacement of the hindbrain. The aim of the study was to determine whether in fetuses with spina bifida this displacement of the brain is evident from the first trimester of pregnancy. METHODS: In women undergoing routine ultrasound examination at 11-13 weeks' gestation as part of screening for chromosomal abnormalities, a mid-sagittal view of the fetal face was obtained to measure nuchal translucency thickness and assess the nasal bone. In this view the fourth ventricle, which presents as an intracranial translucency (IT) between the brain stem and choroid plexus, is easily visible. We measured the anteroposterior diameter of the fourth ventricle in 200 normal fetuses and in four fetuses with spina bifida. RESULTS: In the normal fetuses the fourth ventricle was always visible and the median anteroposterior diameter increased from 1.5 mm at a crown-rump length (CRL) of 45 mm to 2.5 mm at a CRL of 84 mm. In the four fetuses with spina bifida the ventricle was compressed by the caudally displaced hindbrain and no IT could be seen. CONCLUSION: The mid-sagittal view of the face as routinely used in screening for chromosomal defects can also be used for early detection of open spina bifida.

Doppler assessment of tracheal fluid flow during fetal breathing movements in cases of congenital diaphragmatic hernia.

OBJECTIVE: The purpose of this investigation was to examine the characteristics of breathing-related fluid flow in the trachea of human fetuses with congenital diaphragmatic hernia in the hopes of developing a standard for the prenatal diagnosis of the degree of severity of the resulting pulmonary hypoplasia. Our ultimate goal is the prediction of postnatal mortality in fetuses with congenital diaphragmatic hernia. SUBJECTS AND METHODS: The study comprised six cases of isolated congenital diaphragmatic hernia (one on the right side; five on the left) varying in gestational age from 26 to 36 weeks. Four of the patients survived after surgical repair and two died during the neonatal period owing to lung hypoplasia. Color Doppler was used to visualize the fluid displacement in the trachea generated by fetal breathing movements. Spectral Doppler was then used to analyze the fluid flow velocity waveforms. More than 40 continuous breathing cycles (inspiration + expiration) were recorded for each case. We distinguished between regular and irregular patterns. RESULTS: Only the regular breathing phases, defined as five or more consecutive cycles of symmetric appearance, were considered for analysis. The inspiration and expiration times, the peak velocity of inspired and expired fluid and the volume obtained by integration of the tracheal fluid flow displaced during fetal breathing were compared with those of five healthy fetuses for each gestational age. Only the tracheal volume flow was helpful in predicting outcome. In normal pregnancies this parameter increased from 0.21 +/- 0.10 ml/breath (mean +/- SD) at 26 weeks to 1.37 +/- 0.48 ml/breath at 36 weeks of gestation. A significantly low (p < 0.05) volume flow was found only in the fetuses with congenital diaphragmatic hernia with a lethal postnatal outcome, whereas this parameter was normal in all survivors. CONCLUSIONS: Our preliminary observations suggest that the tracheal volume flow during fetal breathing activity is related to lung growth. In fetuses with severe lung hypoplasia one would expect a significant reduction in this parameter as an expression of deficient fetal lung growth. The displaced fluid volume per breath in the trachea of human fetuses as assessed by Doppler ultrasound may be a useful predictor of outcome in cases of isolated congenital diaphragmatic hernia.

Doppler assessment of tracheal and nasal fluid flow during fetal breathing movements: preliminary observations.

Our aim was to determine if it was technically possible to assess fetal tracheal fluid flow during fetal breathing movements, and to compare the data obtained with those recorded in the fetal nasopharynx. Tracheal and nasal fluid flow was analyzed in ten uncomplicated pregnancies, the gestational age ranging between 28 and 38 weeks. Color Doppler was used to detect the fluid displacement in the trachea generated by fetal breathing movements. Spectral Doppler was then used to analyze the fluid flow velocity waveforms. During the same breathing episode, nasal fluid flow was assessed by the same technique. The inspiration and expiration times were variable and not statistically comparable for both nasal and tracheal flow. Peak velocities of inspired and expired fluid were higher in the trachea than in the nose (p < 0.05). We found that the peak velocity of tracheal flow waveforms was significantly higher for inspiration than expiration (p < 0.05). No significant differences were found in the time velocity integral between inspiration and expiration (p = 0.79). The calculated intratracheal flow volume displaced during one breathing cycle increased from 1.3 to 5.0 ml with advancing gestation. Assessment of nasal and tracheal flow, using color and spectral Doppler, is feasible in the human fetus. Intratracheal flow measurements may provide an insight into the effect of fetal breathing movements on lung fluid in the human fetus.

The fetal 'heart-sparing effect' detected by the assessment of coronary blood flow: a further ominous sign of fetal compromise.

Fifteen years after its introduction in obstetrics, Doppler sonography can now be considered to be more than a useful tool in differentiating fetuses at low or high risk for adverse perinatal outcome. In compromised fetuses, it allows very reliable assessment of the actual condition of the fetus in the cascade of deterioration, enabling an optimized perinatal management. The visualization of coronary flow, as presented in this issue of the Journal, is an important part of the cascade of abnormal hemodynamic events detectable by Doppler in such compromised fetuses.

[Assessment of peripheral hemodynamics of the fetus using Doppler ultrasound]. / Die Einschätzung der peripheren Hämodynamik des Feten mittels Dopplerultraschall.

Analysis of foetal haemodynamics using Doppler ultrasound is widely applicable in obstetrics in assessing foetal well-being. To evaluate the parameters of foetal circulation we examined 205 pregnant women to ascertain normal velocity ranges of the foetal internal carotid artery and the foetal renal artery. By establishing the ratio between the pulsatility indices of the foetal internal carotid artery, the foetal aorta and the renal artery of the foetus, standards of these were obtained. From this it seems to be possible to gain information on the extent and degree of the centralisation of foetal blood circulation.

[Assessment of uteroplacental circulation in uncomplicated pregnancies using pulsed Doppler ultrasound]. / Erfassung der uteroplazentaren Durchblutung ungestörter Schwangerschaften mittels gepulstem Doppler Ultraschall.

The Doppler sonography enable as a new non-invasive procedure the assessment of the uteroplacental circulation. 209 blood flow measurements (pulsed wave Doppler) were recorded between the 20th and 40th weeks of gestation from the arcuate arteries in 130 women with uncomplicated pregnancy. The S/D Ratio, the Resistance Index (RI) and the Pulsatility Index (PI) were calculated. These Indices show throughout the observation time persisting low values which reflect the optimal uteroplacental circulation in a system with low downstream impedance. We found that the S/D Ratio and the RI are appropriate parameters in the qualitative analysis of the uteroplacental perfusion. On the other side we could demonstrate that the PI depends on the maternal heart rate which explains the high variability of the values. Therefore is the PI not appropriate for the impedance measurements in uteroplacental vessels.

[Flowmetry of the fetal renal artery--a possibility for improving the assessment of fetal circulatory centralization]. / Die Flowmetrie der fetalen Arteria renalis--eine Möglichkeit zur Verbesserung der Einschätzung des Ausmasses der fetalen Kreislaufzentralisierung.

The use of flowmetry of the foetal renal artery offers a diagnostic improvement by analysing intrauterine centralisation of the foetal circulation. We used the examination results of 82 pregnant women, who were in intensive prenatal care, to check the prediction of foetal distress using the flowmetry of the renal artery. In foetuses showing an increased flow resistance of the aorta and a pathological flow of the renal artery, the rate of caesarian section, necessitated by foetal distress, was 63.6%. By the forming of quotients from the pulsatility indices of the internal carotid artery and the aorta on the one hand, and the renal artery and the internal carotid artery on the other hand, it seems to be possible to get information about the severity of the centralisation of the foetal circulation by existence of an intrauterine hypoxia. The rate of the operative delivery as a consequence of a foetal distress rises from 6.6% with normal PI quotients to 83.4% if both quotients are outside the double standard deviation.