H.J. Hoogland

Relation between ultrasonographic evidence of ovulation and hormonal parameters: luteinizing hormone surge and initial progesterone rise

Relations between ultrasonographic signs of ovulation, the luteinizing hormone (LH) surge, and progesterone rise were documented in 28 and 24 spontaneous ovulations, respectively. Two definitions for LH surge were applied to a series of daily LH determinations. The first LH rise was recorded 48 to 11 hours before ultrasonographic signs of ovulation. The best estimate of the LH peak preceded ovulation by 24 to 11 hours, two extremes excluded. The mean progesterone values during the observed ovulation period were in agreement with data in the literature concerning ovulation period were in agreement with data in the literature concerning ovulation timing by corpus luteum histologic features. A considerable intercycle variation is reported in progesterone level and in the slope of the progesterone increase around ovulation. It is concluded that ultrasonographic signs of ovulation might be closely related to anatomic ovulation.

Interexaminer Variability of Fetal Doppler Velocity Waveforms

A study was made of the interexaminer variability of Doppler velocity waveform determinations of the fetal circulation. Three investigators recorded Doppler ultrasound tracings of the blood velocity in the fetal thoracic and abdominal aorta and umbilical artery in 23 uncomplicated pregnancies. Of these recordings, a hard copy was made, and the pulsatility indices were computed. An analysis of variance was performed and the reliability calculated. The interexaminer variability was nonsignificant in measurements of the three blood vessels under examination. Both thoracic and abdominal aorta measurements showed poor reliability (intraclass correlation coefficient of reliability 0.30 and 0.19, respectively) due to high random errors. Umbilical artery measurements showed a better reliability (intraclass correlation coefficient of reliability 0.61), and, therefore, these hold the greatest clinical applicability.

Three months use of third-generation oral contraceptives does not affect artery wall properties.

In several studies, artery wall properties have been shown to differ between men and women. It has been hypothesized that these differences may result from hormonal influences but, in a previous study, we were unable to detect any influence of the menstrual cycle on artery wall properties. Therefore, we investigated the differences in artery wall properties, if any, between the menstrual cycle and the use of a third-generation oral contraceptive for 3 months. We investigated the right common carotid (CCA) and femoral (CFA) arteries of normotensive young (18-25-y-old) women volunteers (n = 14). The arterial cross-sectional distensibility and compliance coefficients were determined by means of a specially designed ultrasonic wall-tracking device and automatic brachial artery cuff blood-pressure measurements. The menstrual cycles and the cycles during oral contraceptive use (30 microg ethinylestradiol and 75 microg gestodene) were monitored by ultrasonographic evaluation and the assessment of plasma levels of 17beta-oestradiol and progesterone. The distensibility and cross-sectional compliance coefficients of both the CCA and CFA did not differ significantly between the menstrual cycle and the use of oral contraceptives, despite different ovarian hormone levels. Brachial arterial blood pressure was also not affected. We conclude that 3 months use of a third-generation oral contraceptive does not influence the wall properties of peripheral arteries and cannot explain the observed difference between genders. The absence of a rise in blood pressure and the low androgenic profile of this specific oral contraceptive may have contributed to our findings.

A Prospective Study of the Umbilical Artery Waveform in Appropriate-for-Date and Growth-Retarded Fetuses

Blood velocity waveforms were obtained by a combination of real-time B-mode and pulsed Doppler (2 MHz) ultrasound from the umbilical artery. In a prospective study, velocity waveforms of the umbilical artery were analyzed from 36 patients with single pregnancies. Sonograms were performed every 2nd week from the 18th week menstrual age onwards till labor. A total of 331 velocity profiles were obtained. Reference values were obtained from 27 patients with uncomplicated pregnancies. Abnormal waveforms were found in 9 cases. A comparison was made between the normal and abnormal group with regard to placental impedance indices [resistance index (RI), A/B ratio and pulsatility index (PI)]. The sensitivity, specificity, predictive values of each mentioned index were determined. The sensitivity of the PI and the RI is the same: 77.8%, the sensitivity of the A/B ratio is 66.7%. The specificity is also slightly higher for the PI and RI than for the A/B ratio (81.5, 81.5 and 77.5%, respectively). The same can be said for the predictive values (predictive value with positive result, 58.3, 58.3 and 50.0%, predictive value with negative result, 91.2, 91.2 and 87.5%). On the basis of these results and theoretical considerations, the PI is preferable to the other two placental impedance indices. It was shown once more that, with certain restrictions, this noninvasive transcutaneous technique reflects fetal well-being.

The influence of maternal exercise on the pulsatility index of the umbilical artery blood velocity waveform

Doppler bloodflow velocity measurements in the umbilical arteries are quite generally used as a parameter for obstetrical management, notwithstanding the fact that restricted knowledge is available about the physiological and pathophysiological mechanisms of human umbilical circulation. The possible effects of maternal haemodynamic changes on the fetal circulation are only scarcely investigated. In a prospective study the effect of maternal exercise on the Pulsatility Index (PI) values measured in the umbilical artery with a pulsed Doppler device was assessed to investigate the need of standardization with respect to maternal exertion. The studied group consisted of 23 women with uncomplicated pregnancies of various gestational age, who underwent a moderate strain. Statistical analysis showed no significant difference in FHR and PI values before and after exercise, so it is concluded that it is not necessary to introduce a period of rest to precede a Doppler investigation.

Technical Aspects of Fetal Doppler Measurements

Doppler ultrasound may be a valuable tool in the estimation of fetal well-being. Nevertheless, a good understanding of the basic principles of ultrasound and the applied circuitry is necessary to obtain useful information. Some physical principles and limitations of ultrasound are discussed and the basics of the electronic devices are mentioned. Furthermore, the parameters used in obstetrical investigations are reviewed.

Characteristics of the Umbilical Artery Velocity Waveform as Function of Measurement Site

In 30 uncomplicated singleton pregnancies, varying in duration between 24 and 40 weeks, the variability of the flow velocity waveform (FVW) along the course of the umbilical artery was investigated. Blood flow velocities were recorded at 4 locations in the vessel: within the fetal abdomen, 0-5 cm from the origin of the umbilical cord, in the free-floating part, and 0-5 cm from its insertion in the placenta. From the Doppler signals recorded, the pulsatility index (PI) and a parameter for the frequency distribution index (FDI) were calculated. PI values differed among the locations, but no unequivocal tendency could be demonstrated. Statistical analysis, including multiple regression analysis for maternal and menstrual age and fetal heart rate, showed no significant difference in PI and FDI values for any of the 4 locations. It can be concluded that in uncomplicated pregnancies, possible changes in FVW (quantified by PI) along the course of the umbilical artery have no clinical relevance. Therefore, standardization for the sampling site when measuring PI in this vessel seems to be unnecessary.

Bladder filling reduces femoral artery wall distension and strain: beware of a full bladder!

During a previous study, we noted that the distension and strain of the femoral artery were relatively low when the bladder was full, a situation normally necessary for transabdominal echography. Therefore, in the present study we investigated the influence of bladder filling, if any, on wall properties of the common femoral artery. The results obtained were compared with those obtained in the common carotid artery. The study was performed on the right common carotid and right common femoral arteries of normotensive young (18-35 y) female volunteers (n = 24). Using a specially designed ultrasonic wall-tracking device and automatic brachial artery cuff blood pressure measurements, arterial distension (absolute change in diameter during the cardiac cycle; deltaD), strain (deltaD/D), and cross-sectional distensibility (DC) and compliance (CC) were determined before and after voiding. Distension and strain of the common femoral artery were significantly lower for a full than for an empty bladder. DC and CC were lower when the bladder was filled, but these differences did not reach the level of significance. Blood pressure as measured at the level of the brachial artery and heart rate were not statistically significantly different during a full or an empty bladder. It is concluded that bladder filling affects femoral artery wall properties, an observation that should be kept in mind when performing studies on artery wall properties at this level of the circulation.

Umbilical artery blood velocimetry: a prospective longitudinal study in search of the intrauterine growth-retarded fetus

In a longitudinal prospective study involving 125 patients, blood velocity waveforms in the umbilical artery were recorded and analyzed from the 15th week of gestation until term to evaluate the predictive value of blood velocity parameters with regard to fetal growth retardation. Measurements were performed with a combined real-time linear array and 2-MHz pulsed Doppler technique. The mean values (+/- 2 S.D.) of the A/B ratio, resistance index (RI) and pulsatility index (PI) were calculated from the 15th to the 40th week of gestation. The degree of intrauterine growth retardation was related to postnatal catch-up growth. Three groups of patients were compared with regard to blood velocity waveform indices. Group NL-I/II: waveform indices (WI) within 2 S.D. of the population mean. Group EL-II: consistently WIs above 2 S.D. of the population mean. Significant differences with regard to neonatal growth variables were found between these groups. In spite of the fact that these differences in growth variables were statistically significant, no clear relationship was found between the velocity waveform indices and true intrauterine growth retardation, defined by a non-birthweight criterion. It seems that umbilical artery velocimetry cannot predict true intrauterine growth retardation.

The blood flow velocity waveform index in the fetal thoracic aorta and its ability to detect fetal compromise in the small for gestational age fetus

In a prospective longitudinal study of 96 patients, mean values of blood velocity waveform indices of the fetal thoracic aorta are established with a combined linear array real-time and pulsed Doppler transducer. The course of the various blood velocity waveforms is elucidated. The most striking finding is the restricted variability of the pulsatility index (PI), resistance index (RI), A/B ratio, acceleration time (AcT) and acceleration time percentage (AcTP) during the last trimester of pregnancy. In 17 proven and evaluable SGA infants the various blood velocity waveform indices were compared with the established mean values. Fourteen of these 17 (82%) infants were proven to be intrauterine growth-retarded (IUGR). Only 3 of these 14 (21%) showed a significant increase in PI values.