Pulsed Doppler Velocimetry Research Articles

Endometrial thickness and uterine artery Doppler parameters as soft markers for prediction of endometrial cancer in postmenopausal bleeding women: a cross-sectional study at tertiary referral hospitals from Vietnam.

ObjectiveTo determine the value of endometrial thickness (ET) and Doppler indices of uterine artery (UtA) as sonographic markers in predicting endometrial cancer (EC) among postmenopausal bleeding (PMB) women in low-resource settings as Vietnam.MethodsThis cross-sectional study was conducted at the Hue University Hospital and Hue Central Hospital between June 2016 and June 2019. The study enrolled all women who complained of PMB and were followed by transvaginal Doppler ultrasound. Their definitive histopathological examination was the gold standard for comparison.ResultsThe UtA Doppler indices, including resistance index (RI), pulsatility index (PI), and peak systolic velocity (PSV), were significantly lower in the malignant group than in the benign group. The threshold values of the UtA, RI ≤0.73 and PI ≤1.42, were found with an area under receiver operating characteristic curve (AUC) of 0.85–0.88, and the sensitivity and specificity were 91.3% and 83.3%, respectively. Unlike PSV, the diagnostic value was the lowest, with an AUC of 0.72. ET was a good predictor for the diagnosis of EC, with an AUC of 0.89. In women with PMB, when using the cutoff value of EC more than 12.5 mm, the sensitivity and specificity were 93.8% and 77.8%, respectively. In addition, the higher the stage of EC, the lower the RI and PI and the greater the EC.ConclusionET, and RI, PI, and PSV of the UtA could help in differentiating malignant from benign endometrial changes. Pulsed ultrasonic Doppler velocimetry seems to play a role in predicting the higher stages of EC. Further studies are needed to confirm these findings.

Laminar and turbulent pipe flow of bentonite suspensions

Abstract The purpose of this paper is to investigate rheology and hydrodynamic behavior of different mass concentration of bentonite suspensions in pipe flow. Bentonite suspensions exhibited shear thinning and yield stress non-Newtonian rheological behavior. Most of the data reported are for the laminar and turbulent flow, data are also included the start-up flow development. The axial velocity distribution was determined using a Ultrasonic Pulsed Doppler Velocimetry technique. The experimental results show a progressive destructuration of the suspensions in the entrance region due to the segregation of the structural elements of the fluid and tend to a steady state and a fully developed laminar pipe flow. In the majority of cases, axisymmetric flow is observed for both laminar and turbulent flow conditions. Also an asymmetry characterizes the axial velocity profiles in the laminar-turbulent transitional flow. In the laminar regime, the flow parameters were fitted by using the Herschel–Bulkley model. For the turbulent flow, the Dodge and Metzner model was applied to fit the experimental data.

RELACIÓN DOPPLER CEREBROPLACENTARIA COMO PREDICTOR DE RESULTADOS PERINATALES ADVERSOS EN GESTANTES DE RIESGO ALTO

OBJETIVOS: evaluar la utilidad y la capacidad predictiva de la relación cerebroplacentaria (RCP) como prueba diagnóstica de resultados perinatales adversos (RPA) en gestantes de riesgo alto. DISEÑO: Se realizó un estudio longitudinal prospectivo con velocimetría Doppler pulsado en arterias umbilicales y cerebrales fetales. MATERIAL Y MÉTODOS: Se seleccionó 72 gestantes de riesgo alto, entre 28 y 41 semanas, excluyéndose a pacientes con embarazo múltiple y anomalía congénita fetal. En todas se determinó los índices de resistencia (IR) de la arteria umbilical (AU) y arteria cerebral media (ACM) fetal y se calculó la relación cerebro placentaria que consiste en el cociente de IR ACM/IR AU, considerándose como valor anormal =< 1. Los resultados perinatales fueron categorizados y correlacionados con los previos índices Doppler. RESULTADOS: La incidencia de RPA fue 59,7%. El flujo de la ACM fue anormal en 25%, de AU en 38,9% encontrándose RCP anormal en 51,4% del total. En el grupo con RCP =< 1, se encontró con alta significancia (p< 0,01) incremento de riesgo de partos prematuros de < 34 semanas. RCIU y peso bajo al nacer y significativamente (p < 0,05) acidosis neonatal precoz, principalmente. La RCP anormal alcanzó mayor exactitud (88,9%), con valor predictivo positivo de 97,3% comparado con los IR anormales de AU y ACM solas, que alcanzaron 68,1% y 57% en exactitud de predicción, respectivamente. CONCLUSIONES: La relación cerebroplacentaria anormal posee alta capacidad predictiva de resultados perinatales adversos en gestantes de riesgo alto, siendo mucho más sensible que los índices de resistencia de las arterias umbilical y cerebral media, individualmente.

Influence of elastic tube deformation on flow behavior of a shear thinning fluid

The non-Newtonian fluid flow characteristics in collapsible elastic tubes are useful to understand biofluid mechanics in human body. We investigated the flow behavior of a shear thinning carboxymethyl-cellulose aqueous solution in a collapsible elastic tube immersed in water filled chamber under compressive transmural (internal minus external) pressure. The collapsed elastic tube shape is determined by computer tomography based image analysis and velocity profiles are monitored using pulsed ultrasound Doppler velocimetry technique. As external pressure increases at a steady volume flow rate, the elastic tube collapses from elliptical to line or area contacted two lobes shape. Since the outlet pressure in collapsed tube with reduced cross sectional area is lower, the compressive transmural pressure is more negative at downstream than that at upstream. When the downstream transmural pressure is −18mbar, the collapsed tube cross sectional area A reduces to one-sixth of the undeformed tube. The corresponding maximum flow velocity in the collapsed tube is about twice than that in undeformed tube. The similarity tube law represents well the experimental variation in A with the transmural pressure. The tube shape and velocity profile are measured along the tube length, the velocity profiles being bi-modal in the two lobes (no line or area contact) shape over the tube length of about 8cm starting from 5cm near the downstream. The velocity profiles gradually turned into uni-modal as the tube deformed into elliptical shape after 13cm length. Consequently, the average shear rate near the tube wall increased from 79 to 243s−1 thereby reducing the viscosity from 0.11 to 0.087Pas at the most collapsed region along the tube length 5–9cm from downstream. The shear thinning solution viscosity decreases as the cross sectional area reduces. The periodic flow characteristics during ramp-up and ramp-down are governed by the volume flow rate and applied external chamber pressure. The maximum velocity at the undeformed elastic tube center increases an order of magnitude as time elapses in a periodic flow cycle.

Evaluation and Management of Peripheral Vascular Injury. Part 1. Western Trauma Association/Critical Decisions in Trauma

This is a position article from members of the Western Trauma Association (WTA). Because there are no prospective randomized trials on the evaluation and management of peripheral vascular trauma, the algorithm (Fig. 1) is based on the expert opinion of WTA members and published observational studies. It may not be applicable at all hospitals caring for injured patients. The algorithm contains letters that correspond to lettered text that is intentionally concise. This Part I algorithm emphasizes evaluation, diagnosis, and need for operation versus a therapeutic procedure performed in interventional radiology, while a Part II algorithm (2011) will focus on operative techniques. Peripheral vascular injures defined as axillobrachial and branches in the upper extremity and femoropopliteal and branches in the lower extremity account for 40% to 75% of all vascular injuries treated in civilian trauma centers.1–4 With the exception of the axillary artery, the long tracks of named arteries and veins in the extremities make them particularly susceptible to either penetrating or blunt trauma. This fact coupled with the smaller diameter of many of these vessels (as compared with those in the thorax or abdomen) and the ability of the patient and others to control external hemorrhage with compression contribute to a low incidence of death in the field.

Pressure-driven flow of a micro-polar fluid: Measurement of the velocity profile

The pressure-driven flow of a suspension of spinning particles in a rectangular channel is studied using an acoustic method. The suspension is made of insulating particles [poly(methyl methacrylate)] dispersed in a slightly conducting oil (Ugilec+Dielec) and is subjected to a direct current electric field. In such a case, the particles are polarized in the direction opposite to that of the electric field and begin to rotate in order to flip their dipoles in the field direction. Such a rotation of the particles is known as Quincke rotation and is responsible for an important decrease of the effective viscosity of the suspension. Indeed, due to the electric torque exerted on the particles, the stress tensor in the suspension is not symmetric anymore and a driving effect arises from the anti-symmetric part. When such a suspension flows through a rectangular channel, the velocity profile is expected to deviate from the usual Poiseuille flow. In this paper, the velocity profiles are measured using pulsed ultrasound Doppler velocimetry technique. They compare well to those that are computed from the otherwise measured rheological law.

Simultaneous measurements of the solid particles velocity and concentration profiles in two phase flow by pulsed ultrasonic doppler velocimetry

In this experimental study, the pulsed ultrasonic Doppler velocimetry was used to measure simultaneously the local velocity and the local concentration in a flow of solid-liquid suspension in a horizontal pipe. In order to distinguish between the Doppler signals coming from the continuous phase, water and those of the glass bead particles larger than the Kolmogorov length scale and the wavelength of the ultrasonic wave, a threshold is imposed on the integral of the power spectral density of the Doppler signal. The new approach measurement of the local concentration was used. It consists of counting a number NP of the Doppler signals of the solid particles crossing the measurement volume and a number NPt of the Doppler signals of the solid particles crossing the control volume. The concentration profile is then represented by the ration NP / NPt. The results obtained show that the suspension of fine particles, which represents a tracer, behaves as a homogenous fluid. For large particles, we confirmed the existence of the slip velocity and the effects of both concentration and size particle on the turbulence. The use of two distinct measurement volumes allows the direct determination of the turbulent length scales. The results show that the turbulence characteristics of the carried fluid are modified by the presence of the solid particles.

Unsteady Wall Shear Stress in Transient Flow Using Electrochemical Method

Experimental measurements of the wall shear stress combined with those of the velocity profiles via the electrochemical technique and ultrasonic pulsed Doppler velocimetry are used to analyze the flow behavior in transient flows caused by a downstream short pipe valve closure. The Reynolds number of the steady flow based on the pipe diameter is Re=148,600. The results show that the quasisteady approach of representing unsteady friction is valid during the initial phase for relatively large decelerations. For higher decelerations, the unsteady wall shear stress is consistently higher than the quasisteady values obtained from the velocity profiles. Attention has been focused on the friction acceleration model. The results obtained from this study show the ability of the electrochemical method in determining the local unsteady wall shear stress even in severe decelerating transient flows.

Experimental techniques for multiphase flows

This review discusses experimental techniques that provide an accurate spatial and temporal measurement of the fields used to describe multiphase systems for a wide range of concentrations, velocities, and chemical constituents. Five methods are discussed: magnetic resonance imaging (MRI), ultrasonic pulsed Doppler velocimetry (UPDV), electrical impedance tomography (EIT), x-ray radiography, and neutron radiography. All of the techniques are capable of measuring the distribution of solids in suspensions. The most versatile technique is MRI, which can be used for spatially resolved measurements of concentration, velocity, chemical constituents, and diffusivity. The ability to measure concentration allows for the study of sedimentation and shear-induced migration. One-dimensional and two-dimensional velocity profiles have been measured with suspensions, emulsions, and a range of other complex liquids. Chemical shift MRI can discriminate between different constituents in an emulsion where diffusivity measurements allow the particle size to be determined. UPDV is an alternative technique for velocity measurement. There are some limitations regarding the ability to map complex flow fields as a result of the attenuation of the ultrasonic wave in concentrated systems that have high viscosities or where multiple scattering effects may be present. When combined with measurements of the pressure drop, both MRI and UPDV can provide local values of viscosity in pipe flow. EIT is a low cost means of measuring concentration profiles and has been used to study shear-induced migration in pipe flow. Both x-ray and neutron radiographes are used to image structures in flowing suspensions, but both require highly specialized facilities.

Characteristics of fiber suspension flow in a rectangular channel

Velocity profile of fiber suspension flow in a rectangular channel is measured by pulsed ultrasonic Doppler velocimetry (PUDV), and the effect of fiber concentration and Reynolds number on the shape of the velocity profile is investigated. Five types of flow behavior are observed when fiber concentration increases or flow rate decreases progressively. The turbulent velocity profiles of fiber suspension can be described by a correlation with fiber concentration, nl 3, and Reynolds number, Re as the main parameters. The presence of fiber in the suspension will reduce the turbulence intensity and thus reduce the turbulent momentum transfer. On the other hand, fibers in the suspension have the tendency to form fiber networks, which will increase the momentum transfer. The relative contribution of these two types of momentum flux will determine the final shape of the velocity profile.

Wall shear stress measurement in a turbulent pipe flow using ultrasound Doppler velocimetry

A turbulent boundary layer of a water flow is investigated by means of pulsed ultrasound Doppler velocimetry. The advantage of this method is the acquisition of complete velocity profiles along the sound propagation line within very short time intervals. The shear stress velocity, used for normalizing the velocity profiles, was determined by fitting the profiles to the universal profiles in a turbulent boundary layer obtained from Prandtl's mixing length theory. A coordinate transformation in the near-wall region is proposed to allocate the velocity data to "true" wall distances. From the experimental values of the wall shear stress velocity, the friction factors for a turbulent pipe flow are calculated and compared to the Blasius law. The overall error in measurement was estimated to ±8.4%.

The role of thromboelastography in conjunction with second trimester uterine artery Doppler velocimetry in the prediction of adverse pregnancy outcome

Purpose: A pilot, prospective study to evaluate the use of thromboelastography in conjunction with uterine artery Doppler in the second trimester as predictors of pre‐eclampsia and IUGR (intrauterine growth restriction defined as birth weight below the 5th centile for gestational age).Methods: Two‐hundred and forty‐nine (249) unselected pregnant women were recruited at their booking appointment in the Royal Free Hospital. They underwent thromboelastography assessment and color flow/pulsed Doppler imaging of both uterine arteries at 20–24 weeks gestation. Standard parameters were measured from each thromboelastography tracing (R, reaction time; K, clot formation time; A, angle; MA, maximum amplitude). The presence or absence of notches in the flow velocity waveform was noted and the resistance index measured. The main outcome measures were pre‐eclampsia and IUGR.Results: Twenty‐three pregnancies (9.2%) were complicated by IUGR and 10 (4%) by pre‐eclampsia. Assessment using abnormal Doppler velocimetry, defined as bilateral notches/mean RI ≥ 0.55 (27 cases) or unilateral notch/mean RI ≥ 0.65 (5 cases), demonstrated 52% (95% CI 33–71%) sensitivity for IUGR and 40% (CI 17–69%) for pre‐eclampsia with positive predictive values 37.5% (23–55%) and 12.5% (5–28%), respectively. Furthermore, in the pregnancies complicated by an adverse outcome, the groups with normal (14 cases) and abnormal (15 cases) Doppler velocimetry did not differ significantly in any of the thromboelastography parameters (Mann–Whitney test for comparisons).Conclusion: Pulsed Doppler velocimetry of the uterine arteries in the second trimester is an established predictor of adverse pregnancy outcome. The additional use of thromboelastography assessment does not appear to contribute significantly in providing further information. As this is a pilot study, larger trials are required to delineate its role.

Influência do Tabagismo no Sistema Vascular Materno-fetal: estudo com Dopplervelocimetria

Objetivo: avaliar a influência do tabagismo materno na dinâmica vascular materno-fetal, por meio da dopplervelocimetria obstétrica das artérias uterinas, umbilical e cerebral média. Métodos: estudo prospectivo em 42 gestantes saudáveis, sendo 20 fumantes e 22 não-fumantes. Foram realizadas ultra-sonografias para determinar o tempo de gestação e exame de dopplervelocimetria pulsátil das artérias uterinas, umbilical e cerebral média nas 24ª, 28ª, 32ª e 36ª semana para avaliar o fluxo vascular materno-fetal. As fumantes foram orientadas a não fumar por pelo menos 2 horas antes do exame. Resultados: o índice de resistência (IR) médio das artérias uterinas D e E foi maior no grupo de fumantes na 36ª semana com média de 0,50 e desvio padrão de 0,034. O índice de pulsatilidade (IP) da artéria umbilical foi maior no grupo de fumantes na 28ª semana [x (DP) = 1,135 (0,182)], p = 0,008; o IP da artéria cerebral média (ACM) não se mostrou diferente entre os grupos, porém, a relação IP ACM/umbilical foi menor no grupo de fumantes, na 32ª semana [x (DP) = 1,9 (0,291)], p = 0,027 e na 36ª semana [x (DP) = 1,850 (0,465)], p = 0,014. Conclusões: os índices de dopplervelocimetria mostraram que no grupo de fumantes há aumento na resistência da circulação útero-placentária e feto-placentária, associado a concomitante diminuição na resistência da ACM, mimetizando uma tendência do tabagismo levar à hipóxia crônica do feto.

Systemic and renal hemodynamics after moderate hemodilution with HbOCs in anesthetized rabbits.

Hb-based O(2)-carrying solutions (HbOCs) have been developed as red blood cell substitutes for use in patients undergoing hemodilution. Variously modified Hb with diverse solution properties have been shown to produce variable hemodynamic responses. We examined, through pulsed-Doppler velocimetry, the systemic and renal hemodynamic effects of dextran-benzene-tetracarboxylate-conjugated (Hb-Dex-BTC), bis(3,5-dibromosalicyl)fumarate cross-linked (alphaalpha-Hb), and o-raffinose-polymerized (o-raffinose-Hb) Hb perfused in rabbits after moderate hemodilution (30% hematocrit), and we compared the effects of these Hb solutions with the effects elicited by plasma volume expanders. In addition, vascular hindrance (resistance/blood viscosity at 128.5 s(-1)) was calculated to determine whether a moderate decrease in the viscosity of blood mixed with HbOCs may impair vasoconstriction as a result of autoregulation after infusion of cell-free Hb. No changes were observed in renal hemodynamics after hemodilution with reference or Hb solutions. Increase in blood pressure and vascular resistance was found with Hb-Dex-BTC and alphaalpha-Hb (for 180 min) and, to a lesser extent, with o-raffinose-Hb (for 120 min). Furthermore, Hb-Dex-BTC (high viscosity) and o-raffinose-Hb (medium viscosity) induced comparable increases in vascular hindrance (from 0.091 to 0. 159 and from 0.092 to 0.162 cm(-1), respectively) but far less than that produced by alphaalpha-Hb (low viscosity, from 0.092 to 0.200 cm(-1)). These results suggest that maintaining the viscosity of blood by infusing solutions with high viscosity makes it possible to limit vasoconstriction due to autoregulation mechanisms and mainly caused by hemodilution per se.

Prediction and prevention of pregnancy-induced hypertensive disorders

Because hypertensive disorders complicating pregnancy are common and constitute a leading cause of maternal, fetal and neonatal morbidity and mortality, prevention attempts appear to be justified. Primary prevention is only possible by avoiding pregnancy. Secondary prevention requires identification of patients at risk. A large number of predictive methods have been published and the majority appear to be of no or limited value. At present only the determination of inactive urinary kallikrein and uteroplacental colour–pulsed Doppler velocimetry show promise and require further assessment. Analysis of the many interventions advocated for prevention of pre-eclampsia reveals that only dietary calcium supplementation and prophylactic low-dose aspirin have shown promise of efficacy in small controlled clinical trials, but the results of large, multicentre trials are disappointing. The disappointing results obtained in large, multicentre trials may be explained, at least in part, by the lack of strict eligibility criteria and end-points and by low patient compliance. Prophylactic low-dose aspirin is recommended in women at high risk because it is associated with a moderate reduction in risk, may reduce the severity of pre-eclampsia if it develops and appears to be safe for mother and infant. The present data do not support any prophylactic intervention in pregnant women at low or medium risk.

Analysis of blood flow in adnexal tumors by using color doppler imaging and pulsed spectral analysis

Because of various contradictory reports in the literature and an increasingly urgent need for preoperative evaluation of adnexal masses before laparoscopic surgery, our aim was to disclose if examination by means of color Doppler ultrasound is useful in distinguishing benign from malignant adnexal tumors in our population. Prior to surgery, pulsed color Doppler velocimetry of the adnexal blood supply was performed in a prospective study in 80 patients with benign and 40 with malignant adnexal tumors. Vascularization was equally frequent in both groups of tumors. Blood vessels of benign tumors had a diffuse, intraseptal or intraproliferative location significantly more often and malignant tumor vessels more often exhibited a diffuse, intraseptal or intraproliferative location ( p < 0.01). The mean value of RI ± SD was 0.56 ± 0.14 in benign and 0.33 ± 0.13 in malignant tumors. The differences in RI between benign and malignant tumors are statistically significant ( p < 0.01). In detecting malignant adnexal tumors, the sensitivity of RI ≤ 0.40 is 82%, its specificity 97%, positive predictive value 94%, negative predictive value 92% and its accuracy 92%. The analysis of vascularization presence seems not to have any value in predicting the nature of adnexal tumors, and blood vessels arrangement, as well as measured RI ≤ 0.40, allows us to predict the presence of malignancy with limited reliability.

Doppler velocimetry of growth-restricted fetuses in an ovine model of placental insufficiency

Objective: With an ovine model in which growth restriction was induced by exposure to heat stress, our aims were as follows: (1) to describe the normal gestational age–related changes in Doppler velocimetry in the ovine fetal aorta and umbilical artery and (2) to compare Doppler velocimetry between heat-stressed and non-heat-stressed fetuses. Study Design: Five ewes were exposed to heat stress for 55 days beginning at 35 days' gestation. Five ewes were not exposed and served as controls. Aortic and umbilical artery pulsed Doppler velocimetry was obtained, including the systolic/diastolic ratio, pulsatility index, and resistance index. Data were obtained between 50 and 120 days' gestation. Linear regression analysis was used to analyze gestational age–related changes in velocimetry. Comparison of mean index values between heat-stressed and non-heat-stressed fetuses were made with analysis of variance. Results: Heat-stressed fetuses demonstrated significantly higher systolic/diastolic ratios and pulsatility index values for both umbilical artery ( p < 0.025; p < 0.033) and aorta ( p < 0.017; p < 0.022) compared with controls. The umbilical artery and aortic resistance index values were not different between groups ( p < 0.079; p < 0.28). The slopes for each of the Doppler index values were negative in both normal and heat-stressed fetuses. Umbilical artery and aortic end-diastolic flows remained absent through the first 70 days of gestation in both groups. Conclusion: Doppler velocimetry index values decrease with increasing gestational age, reflecting decreased placental bed vascular resistance. The higher Doppler index values seen in the heat-stressed group are consistent with increased placental vascular resistance. The normal absence of diastolic flow until 70 days' gestation is similar to the pattern described in humans. (Am J Obstet Gynecol 1998;178:451-6.)

Proposition of a technique to assess the vasoactive effects of hemoglobin-based oxygen carrying solutions in vivo: preliminary results in the rabbit aorta.

Most of hemoglobin-based oxygen carriers (HBOCs) increase the blood pressure after injection in the blood stream by a mechanism involving one or more factors that contribute to the regulation of the vascular tone. Many techniques make it possible to study the vascular effects of HBOCs both in vivo and in vitro. The in vivo methods assess the blood pressure and some estimated regional blood flows (use of radioactive or colored microspheres). Measurements of the real vessel diameter and blood flow would be useful to understand hemoglobin-mediated vasoconstriction mechanism. Our purpose was to elaborate an experimental model in anesthetized rabbits to monitor the diameter and the blood flow velocity in the same vessel in order to calculate the absolute blood flow. The blood flow velocity (in cm/s) was assessed by pulsed Doppler velocimetry and the diameter (in mm) was assessed by a technique of Wall Tracking. The first results indicate that the method is well adapted to study the effects of resuscitative fluids (plasma and blood substitutes) on the aorta vascular tone after hemodilution or resuscitation from severe hemorrhage.

Cerebral and Umbilical Vascular Resistance Response to Vibroacoustic Stimulation in Growth-Restricted Fetuses

Objective: To test the hypothesis that after vibroacoustic stimulation the ratio between cerebral vascular and umbilical vascular resistance in the growth-restricted fetus is different from that in the normal fetus.Methods: The pulsatility index (PI) of the middle cerebral artery and that of the umbilical artery (UA) were measured by pulsed Doppler velocimetry in 30 normal and 14 growth-restricted fetuses before and after vibroacoustic stimulation. The ratios of cerebral PI to UA PI and the changes in PI after vibroacoustic stimulation were calculated. Comparisons were made using the Wilcoxon rank-sum test or signed-rank test. The statistical power of the study was 80%.Results: Mean (± standard deviation) cerebral PI values before vibroacoustic stimulation (1.50 ± 0.29 in normals and 1.29 ± 0.26 in the fetal growth restriction [FGR] group) and UA PI values (1.00 ± 0.18 in normals and 1.15 ± 0.24 in the FGR group) were significantly different between groups (P < .04) and significantly decreased after vibroacoustic stimulation (P < .05). Although the cerebral to UA PI ratios (1.50 ± 0.38 in normals and 1.13 ± 0.33 in the FGR group) were significantly different between groups (P < .008), the values remained the same after vibroacoustic stimulation (P = .39 and .80, respectively). In all fetuses the fetal heart rate accelerated after vibroacoustic stimulation.Conclusion: Cerebral vascular resistance was lower and umbilical vascular resistance higher in the growth-restricted fetuses than in normals. The vascular resistance response after vibroacoustic stimulation in the growth-restricted fetus was not significantly different from the response of the normal fetus, suggesting preservation of regulation of resistance.

Transvaginal Pulsed Doppler Velocimetry Measurement of Blood Flow Velocity in the Ovarian Arteries through the Menstrual Phase

Transvaginal Pulsed Doppler Velocimetry Measurement of Blood Flow Velocity in the Ovarian Arteries through the Menstrual Phase