Umbilical Vein Volume Flow Research Articles

Comparison of Variations Between Spectral Doppler and Gaussian Surface Integration Methods for Umbilical Vein Blood Volume Flow.

We are studying a new method for estimating blood volume flow that uses 3-dimensional ultrasound to measure the total integrated flux through an ultrasound-generated Gaussian surface that intersects the umbilical cord. This method makes none of the assumptions typically required with standard 1-dimensional spectral Doppler volume flow estimates. We compared the variations in volume flow estimates between techniques in the umbilical vein. The study was Institutional Review Board approved, and all 12 patients gave informed consent. Because we had no reference standard for the true umbilical vein volume flow, we compared the variations of the measurements for the flow measurement techniques. At least 3 separate spectral Doppler and 3 separate Gaussian surface measurements were made along the umbilical vein. Means, standard deviations, and coefficients of variation (standard deviation/mean) for the flow estimation techniques were calculated for each patient. P < .05 was considered significant. The ranges of the mean volume flow estimates were 174 to 577 mL/min for the spectral Doppler method and 100 to 341 mL/min for the Gaussian surface integration (GSI) method. The mean standard deviations (mean ± SD) were 161 ± 95 and 45 ± 48 mL/min for the spectral Doppler and GSI methods, respectively (P < .003). The mean coefficients of variation were 0.46 ± 0.17 and 0.18 ± 0.14 for the spectral Doppler and GSI methods respectively (P < 0.002). The new volume flow estimation method using 3-dimensional ultrasound appears to have significantly less variation in estimates than the standard 1-dimensional spectral Doppler method.

Angle-Independent Blood Volume Flow

Standard ultrasound Doppler can estimate volume flow. However, the estimate depends on major assumptions, which include flow that has to be perfectly symmetric around the centerline of the vessel, a perfectly round vessel cross-section, and the Doppler measurements must be angle corrected. These restrictions make volume flow estimates problematic especially in environments where these assumptions do not hold, such as transjugular intrahepatic portosystemic shunts (TIPS) and umbilical cords. With the advent of 3D/4D ultrasound imaging, all of the limitations of ultrasound volume flow measurements can be overcome, potentially producing volume flow estimates that are as easy to obtain as standard color flow Doppler images, i.e. in real time. The method depends on the something called Gauss's theorem. This law states that volume flow is equal to the sum of all of the normal velocity vectors passing through any surface. Simply put, this sum, also known as the total flux, is just the sum of the local products of the velocity of the blood going perpendicularly through every individual element of a surface that cuts across a blood vessel This can be any continuous surface (often known as a C-surface or C-plane), it does not have to be a plane, and the method contains none of the assumptions required for standard volume flow measurement. Thus, this method is angle independent, flow profile independent, and vessel geometry independent. Hence, non-laminar flow profiles produced by the irregular TIPS stent walls or highly tortuous umbilical arteries and veins do not affect this method. We have tested this technique in simulations, phantoms, in in-vivo animal models, and human subjects. The method has proven to work well in all of these settings. In humans, linear regression of data from revised TIPS cases showed an inverse correlation between mean-normalized change in pre- and post-revision shunt volume flow and mean-normalized change in pre- and post-revision portosystemic pressure gradient (r2 = 0.71, P-value = 0.0044). Depth-corrected and weight normalized umbilical vein volume flow measurements in normal and pre-eclampsia subjects showed a statistically significant difference between groups (P = 0.035). Further, these measurements were highly reproducible in the mean estimate with an intra-subject relative standard error (RSE) of 12.1 ± 5.9 % and an intra-measurement RSE of 5.6 ± 1.9 %. This method is easy to perform, accurate, and reproducible. Using 2D ultrasound arrays, it can be in real-time. It could have a major impact on future flow analysis.

Evaluation of Umbilical Vein Blood Volume Flow in Preeclampsia by Angle-Independent 3D Sonography.

To investigate the association between umbilical vein blood volume flow and the condition of preeclampsia in an at-risk maternal patient cohort. Umbilical vein volume flow was quantified by a 3-dimensional (3D) sonographic technique that overcomes several limitations of standard sonographic flow measurement methods. A total of 35 patients, each with a singleton pregnancy, were recruited to provide 5 patients with preeclampsia, derived as a subset from a 26-patient at-risk group, and 9 patients with normal pregnancies. An ultrasound system equipped with a 2.0-8.0-MHz transducer was used to acquire multivolume 3D color flow and power mode data sets to compute the mean umbilical vein volume flow in patients with normal pregnancies and preeclampsia. The gestational ages of the pregnancies ranged from 29.7 to 34.3 weeks in the patients with preeclampsia and from 25.9 to 34.7 weeks in the patients with normal pregnancies. Comparisons between patients with normal pregnancies and those with preeclampsia showed weight-normalized flow with a moderately high separation between groups (P = .11) and depth-corrected, weight-normalized flow with a statistically significant difference between groups (P = .035). Umbilical vein volume flow measurements were highly reproducible in the mean estimate, with an intrapatient relative SE of 12.1% ± 5.9% and an intrameasurement relative SE of 5.6% ± 1.9 %. In patients who developed pregnancy-induced hypertension or severe pregnancy-induced hypertension, umbilical vein volume flow suggested gestational hypertensive disorder before clinical diagnosis. Results indicate that mean depth-corrected, weight-normalized umbilical vein volume flow is reduced in pregnancies complicated by preeclampsia and that volume flow may indicate hypertensive disorder earlier in gestation. Volume flow measurements are highly reproducible, and further study in a larger clinical population is encouraged to determine whether 3D volume flow can complement the management of preeclampsia and, in general, at-risk pregnancy.

550: Relationship between umbilical vein volume flow, umbilical artery and MCA doppler in late preterm growth restricted fetuses

550: Relationship between umbilical vein volume flow, umbilical artery and MCA doppler in late preterm growth restricted fetuses

Umbilical vein vasomotion detected in vivo by serial three-dimensional pixelwise spatially angle-corrected volume flow measurements.

To explore changes in volume flow in the umbilical vein in healthy second-trimester fetuses. This was a prospective observational pilot study performed at Stavanger University Hospital, Norway, between May and October 2013. Serial three-dimensional ultrasound recordings from the umbilical vein were acquired every 30 s in a 5-min period in 43 fetuses at 17-20 weeks' gestation. The recordings were analyzed with pixelwise spatially angle-corrected volume flow measurements. We observed variation in the umbilical vein volume flow in all fetuses, ranging from a mean minimum of 1.01 mL/s to a mean maximum of 2.60 mL/s. The minimum of all measurements was 57% compared with the mean value and the maximum was 148% of the mean value. The individual flow volume measurements ranged between 0.11 and 4.14 mL/s (mean, 1.76 mL/s). Within this range, an undulating course of all perfusion parameters was observed, with a full period of 4-5 min duration. Healthy second-trimester fetuses show cyclical variation in blood flow in the umbilical vein. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

P19.10: Umbilical vein volume flow at 11–14 weeks in monochorionic twin pairs with subsequent twin–twin transfusion or selective intrauterine growth restriction

<scp>P</scp>19.10: Umbilical vein volume flow at 11–14 weeks in monochorionic twin pairs with subsequent twin–twin transfusion or selective intrauterine growth restriction

Umbilical vein volume flow in monochorionic twin pairs at 11–14 weeks

We investigated the umbilical vein volume flow (UVVF) at 11-14 weeks in monochorionic-diamniotic (MCDA) twins, focusing on the occurrence of complications. We considered 87 MCDA pregnancies. We used "E-flow" to detect the umbilical vein and measured the mean velocities and diameters of veins, also calculating the UVVF. Pregnancies were divided into four groups: a (twin-to-twin transfusion, TTTS); b (selective intrauterine growth restriction, sIUGR); c (discordance of fluid, DF); and d (with "normal" outcome). The main outcome of the study was the assessment of the difference of UVVF between twin 1 and twin 2 (larger and smaller twin). In eight of eight pairs of group a and seven of seven pairs of group b, the UVVF of fetuses 1 were significantly different than fetuses 2 (P<0.05). The UVVFs of fetuses 2 of group a were significantly lower in respect to the UVVFs of fetuses 2 of group d (P<0.05). We provide evidence of an important difference in UVVF in pairs that successively developed TTTS or sIUGR. The smaller fetuses of group a (TTTS) showed a lower venous return than fetuses 2 of group d (normal). First-trimester UVVF is lower in fetuses with a smaller crown-rump length in twin pairs at risk of TTTS or IUGR.

Estimation of fetal oxygen uptake in human term pregnancies

Objective. Umbilical oxygen (O2) uptake is a parameter of basic physiologic interest. It has been extensively studied in chronically catheterized animals but very few data have been obtained acutely in humans. Recent developments in ultrasound technology allow the estimation of umbilical venous blood flow in utero.Methods. In all, 26 normal term pregnancies were studied at the time of elective cesarean section in order to evaluate fetal O2 uptake as the product of umbilical blood flow and umbilical O2 veno-arterial difference. An ultrasound evaluation was performed within 1 h from delivery: umbilical vein area and flow velocity were recorded to calculate umbilical vein volume flow (Qumb). Blood samples from the umbilical vein (uv) and artery (ua) were obtained at the time of fetal extraction for respiratory gases and acid–base evaluation.Results. Umbilical O2 uptake was calculated as Qumb • (uv-ua)O2 content: an average value of 0.84 ± 0.40 mmol/min was obtained. Umbilical O2 uptake per kg was 0.25 ± 0.12 mmol/kg/min, significantly related to fetal O2 delivery.Conclusions. We estimated umbilical blood flow by ultrasound and we measured umbilical O2 uptake at term obtaining a value of umbilical O2 uptake/kg similar to what previously reported in human pregnancies and chronically catheterized animals.

OP34.06: Umbilical vein volume flow measurement in monochorionic twins

OP34.06: Umbilical vein volume flow measurement in monochorionic twins

OP20.03: Reliability of the fetal umbilical vein volume flow measurement between different operators

OP20.03: Reliability of the fetal umbilical vein volume flow measurement between different operators

OP10.02: The CHOP cardiovascular score: a method for quantification of cardiovascular abnormality in the twin–twin transfusion syndrome

Objectives: Umbilical vein volume flow (UVVF), calculated as velocity (cm/s) times transversal section area at the straight portion of the intra-abdominal umbilical vein (cm2), is an interesting parameter to study in twin–twin transfusion syndrome (TTTS). Recipients were found to have 2 to 3 times higher UVVF than donors, but this parameter was not studied in normal monochorionic pregnancies. Methods: Comparison of recipient to donor (rec/don) UVVF ratio and bigger-to-smaller UVVF ratio in non-TTTS monochorionic twin pregnancies (control group). The method of dividing the same parameter from each pair of twins aimed to emulate other factors such as gestational age and maternal condition, which change between pregnancies. The control group consisted of monochorionic twin pregnancies with normal umbilical artery Doppler and normal amniotic fluid (2 to 8 cm of MVP), between 18 and 26 weeks. Results: Eight-four TTTS and 24 normal monochorionic twin pregnancies were compared. The median weight discordance was 1.3 (rec/don) and 1.2 respectively (big/small, Wilcoxon P < 0.7). The UVVF ratio between recipients and donors (UVVF R/D) was greater than that of the bigger to smaller UVVF ratio from normal monochorionic twins (medians 2.2 and 1.3, Wilcoxon P < 0.001). Conclusions: This study shows that UVVF R/D imbalance occurs in cases with the polyhydramnios and oligohydramnios sequence found in TTTS, and that normal monchorionic pregnancies lack this imbalance. The difference is not due to fetal weight discordance as it was shown that normal monochorionic twins had similar discordance. The parameter has still not proven to be useful in screening for early diagnosis by this methodology, but it describes that UVVF imbalance between twins does not exist in normal monochorionic pregnancies. OP10.02 The CHOP cardiovascular score: a method for quantification of cardiovascular abnormality in the twin–twin transfusion syndrome

OP10.01: Umbilical vein volume flow imbalance between twins in TTTS is not seen in normal monochorionic pregnancies.

OP10.01: Umbilical vein volume flow imbalance between twins in TTTS is not seen in normal monochorionic pregnancies.