Juriy W. Wladimiroff

Doppler ultrasound assessment of cerebral blood flow in the human fetus

Summary. A mechanical sector and linear array real‐time scanner combined with a pulsed Doppler system was used for recording the flow velocity waveform in the internal carotid artery, the lower thoracic part of the descending aorta and umbilical artery in the human fetus. A total of 42 fetuses in normal pregnancy and nine growth‐retarded fetuses between 26 and 41 weeks gestation was studied. In normal pregnancy the mean pulsatility index (PI) in the internal carotid artery varied between 1·5 and 1·6, in the descending aorta between 1·7 and 1·8 and in the umbilical artery between 0·7 and 1·3. In the growth‐retarded fetuses the PI was reduced in the internal carotid artery and raised in the descending aorta and umbilical artery, suggesting an increased peripheral vascular resistance in the fetal body and placenta and a compensatory reduction in peripheral vascular resistance in the fetal cerebrum, i.e. a brain‐sparing effect in the presence of fetal hypoxia.

Growth patterns of nondominant ovarian follicles during the normal menstrual cycle

Transvaginal ultrasound examinations were performed in seven normally cycling women to characterize growth of nondominant follicles in both ovaries. Mean follicle number showed little variation throughout the menstrual cycle with no differences between dominant and nondominant ovaries. Up to 11 follicles (greater than or equal to 2 mm) were observed in any one ovary. From observations of the first appearance of the dominant follicle (mean size 9.9 +/- 3.0 [SD] mm), selection was assumed to take place on cycle day 6.3 +/- 2.3. The diameter of nondominant follicles always remained less than 11 mm. Growth of small follicles was established in both dominant and nondominant ovaries up to the time of selection. The late follicular and luteal phases were characterized by a decrease in mean growth slopes of nondominant follicles in the dominant ovary only. These observations may provide in vivo evidence for the concept of intraovarian paracrine mechanisms and may have implications for the sonographic diagnosis of anovulation and monitoring of ovulation induction.

Efficacy of Routine Fetal Ultrasound Screening for Congenital Heart Disease in Normal Pregnancy

BACKGROUND Second trimester routine ultrasound evaluation of the fetal heart by means of the four-chamber view has been proposed for prenatal detection of cardiac anomalies. The aim of this study was to evaluate the efficacy of this procedure. METHODS AND RESULTS A prospective follow-up study on 6922 scanned fetuses was performed. Pregnant women without known risk factors who were scheduled for a routine fetal ultrasound examination between 16 and 24 weeks gestation were invited to participate. Follow-up until 6 months postpartum was available for 5660 subjects (81.8%), of whom 5319 fulfilled all eligibility criteria. by comparing the prenatal diagnosis to the postnatal diagnosis, we obtained sensitivity, specificity, and predictive value (positive and negative). A total of 80 cases of congenital malformations were diagnosed during the study: 44 cases of congenital heart disease, 40 cases of noncardiac malformations, and a combination of the two in 4 cases. The fetal four chamber-view examination was considered abnormal in 7 women who were subsequently referred for extensive fetal ultrasound examination. Two proved to be carrying an affected fetus. Similarly, prenatal referral of 14 women because of suspected noncardiac malformations yielded 12 such cases. The fetal four chamber-view examination had a sensitivity of 4.5% (95% CI, 0.6% to 15%). Sensitivity for noncardiac anomalies was 30% (95% CI, 16.6% to 46.5%). Overall sensitivity of ultrasound examination was 16.3% (95% CI, 2.09% to 48.8%). Specificity and negative predictive value were high (>98%). The positive predictive value was low with wide CIs. CONCLUSIONS These results suggest that the current mode of routine prenatal ultrasound screening for congenital malformations is inefficient, particularly for cardiac anomalies.

Uterine and ovarian flow velocity waveforms in the normal menstrual cycle: a transvaginal Doppler study

A combined transvaginal 2D real-time and pulsed Doppler method was used for recording flow velocity waveforms in the uterine and ovarian arteries from 16 healthy women during the follicular and luteal phase of the normal menstrual cycle. Continuous forward end-diastolic flow velocities were documented in 74% of the ovarian artery and 96.5% of the uterine artery flow velocity waveforms. Comparison of the pulsatility index from the left and right ovarian artery revealed a significantly lower pulsatility index on the side of the ovary bearing the developing corpus luteum, suggesting reduced down-stream impedance or increased blood flow. The pulsatility index from the uterine artery only seems to be marginally involved in the observed impedance changes during the luteal phase of the menstrual cycle.

Fetal Hemodynamic Adaptive Changes Related to Intrauterine Growth: The Generation R Study

Background— It has been suggested that an adverse fetal environment increases susceptibility to hypertension and cardiovascular disease in adult life. This increased risk may result from suboptimal development of the heart and main arteries in utero and from adaptive cardiovascular changes in conditions of reduced fetal growth. The aim of the present study was to evaluate whether reduced fetal growth is associated with fetal circulatory changes and cardiac dysfunction. Methods and Results— This study was embedded in a population-based, prospective cohort study starting in early fetal life. Fetal growth characteristics and fetal circulation variables were assessed with ultrasound and Doppler examinations in 1215 healthy women. The fetal circulation was examined in relation to estimated fetal weight. Higher placental resistance indices were strongly associated with decreased fetal growth. Cerebral resistance showed a gradual decline with reduced fetal growth. Cardiac output, peak systolic velocity of the outflow tracts, and cardiac compliance showed a gradual reduction with diminished fetal growth, whereas intraventricular pressure gradually increased. Conclusions— Decreased fetal growth is associated with adaptive fetal cardiovascular changes. Cardiac remodeling and cardiac output changes are consistent with a gradual increase in afterload and compromised arterial compliance in conditions of decreased fetal growth. These changes have already begun to occur before the stage of clinically apparent fetal growth restriction and may contribute to the increased risk of cardiovascular disease in later life.

The blood flow velocity waveform in the fetal internal carotid and umbilical artery; its relation to fetal behavioural states in normal pregnancy at 37–38 weeks

Summary. The relation between the blood flow velocity waveform in the fetal internal carotid artery (n= 12) and umbilical artery (n= 15) and fetal behavioural states at 37–38 weeks of gestation was studied. In the fetal internal carotid artery, under standardized fetal heart rate conditions, the pulsatility index (PI), as a measure of peripheral vascular resistance, was significantly lower during behavioural state 2F (active sleep) compared with state 1F (quiet sleep) according to the classification by Nijhuis et al. (1982), suggesting increased fetal cerebral blood flow during state 2F. In the umbilical artery, no significant difference in PI between the two behavioural states could be established. This suggests a fetal origin of the state dependency observed in fetal blood flow velocity waveforms.

ACCURACY AND SAFETY OF TRANSVAGINAL SONOGRAPHIC PLACENTAL LOCALIZATION

Transvaginal sonographic localization of the placenta was performed in 100 patients suspected of having placenta previa. Except in one patient, the diagnosis was confirmed at cesarean delivery in all cases of placenta previa found by sonography before delivery, resulting in a 93.3% predictive value of a positive test. The predictive value of a negative test was 97.6%; in two patients a low-insertion placenta diagnosed by sonography was found to be a placenta previa at delivery. The sensitivity and specificity of the technique were 87.5 and 98.8%, respectively. Although in some instances transvaginal sonography was performed during vaginal hemorrhage, aggravation of bleeding was never observed. Transvaginal sonographic localization of the placenta proved to be an accurate and safe diagnostic procedure.

Fetal Atrioventricular Flow-Velocity Waveforms and Their Relation to Arterial and Venous Flow-Velocity Waveforms at 8 to 20 Weeks of Gestation

BACKGROUND Doppler ultrasonography was used to determine the nature and gestational age-related changes of human fetal AV flow-velocity waveforms and to establish their relationship with arterial impedance indexes and venous flow velocities in normal human fetuses between 8 and 20 weeks of gestation. METHODS AND RESULTS Flow-velocity waveform recordings were attempted in 318 singleton pregnancies. After the exclusion criteria were applied, data on 214 women were available for further analysis. Differentiation between E wave and A wave became possible at 9 weeks, whereas distinction between transmittal and transtricuspid valve flow velocities was first achieved at 10 to 11 weeks. A statistically significant nonlinear gestational age-dependent increase was established for all AV waveform parameters, which became linear when related to logarithmically estimated fetal crown-to-rump length. Transtricuspid valve flow velocities were significantly higher than transmittal valve flow velocities. Transmittal valve time-averaged flow velocities were positively correlated with peak diastolic velocities and time-velocity integral of late-diastolic reverse flow in the inferior vena cava. No correlation existed between AV time-averaged velocities and arterial impedance indexes. CONCLUSIONS Monophasic AV flow-velocity waveforms can be recorded as early as 8 weeks of gestation and become biphasic as early as 8 weeks. They demonstrate a linear increase relative to logarithmically estimated fetal crown-to-rump length, suggesting that fetal growth-related increase in volume flow plays a role in this velocity rise. Transtricuspid valve A-wave and E-wave velocities suggest right ventricular predominance as early as the late first trimester of pregnancy. AV flow velocities are not related to arterial downstream impedance.

Transvaginal sonography and abnormal ovarian appearance in menstrual cycle disturbances

Transvaginal ultrasound examinations were performed in 37 oligo- or a-menorrheic women to describe ovarian changes and potential correlations with clinical and some biochemical features of polycystic ovarian syndrome (PCOS). Findings were compared between the right and left ovary and between each of three subsequent examinations of the same ovary. In any one ovary, no significant difference was found between mean ovarian volume, stroma echogenicity, mean follicle number and size. Correlation between ovarian volume and follicle number was strong in all examinations. Follicle number in both ovaries correlated significantly with ovarian stroma echogenicity and some biochemical markers of PCOS. These observations validate the usefulness of transvaginal sonography in demonstrating numerous correlations in menstrual cycle disturbances. The strong necessity to reevaluate sonographic criteria of PCOS is highlighted.

Three-dimensional sonographic measurement of normal fetal brain volume during the second half of pregnancy

OBJECTIVES This study was undertaken to develop a three-dimensional (3D) ultrasound method of measuring fetal brain volume. STUDY DESIGN Serial 3D sonographic measurements of fetal brain volume were made in 68 normal singleton pregnancies at 18 to 34 weeks of gestation. A comparison was made with fetal brain volume estimates from two-dimensional (2D) sonographic measurement of head circumference and published postmortem fetal brain weights. RESULTS Coefficient of variation for fetal brain volume (3D) caused by differences between repeated tests was 10.2% and between analyses of the same recorded volume 2.2%. Median brain volume increases from 34 mL at 18 weeks to 316 mL at 34 weeks. Median brain weight represented approximately 15% of total fetal weight. The 3D ultrasound-derived brain weight is larger than postmortem brain weight. However, this is not so for brain weight derived from total fetal weight at autopsy. A good agreement between 3D and 2D brain volume was found. CONCLUSION Sonographic measurement of fetal brain volume demonstrated an acceptable intraobserver variability and a nearly 10-fold increase during the second half of gestation.