scholarly journals Ultrasound Reference Chart Based on IVF Dates to Estimate Gestational Age at 6–9 weeks’ Gestation

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Pavitra Delpachitra ◽  
Kirsten Palmer ◽  
Joseph Onwude ◽  
Simon Meagher ◽  
Luk Rombauts ◽  
...  

Accurate determination of gestational age underpins good obstetric care. We assessed the performance of six existing ultrasound reference charts to determine gestational age in 1268 singleton IVF pregnancies, where “true” gestational age could be precisely calculated from date of fertilisation. All charts generated dates significantly different to IVF dates (P<0.0001 all comparisons). Thus we generated a new reference chart, The Monash Chart, based on a line of best fit describing crown-rump length across 6 + 1 to 9 + 0 weeks of gestation (true gestational age) in the IVF singleton cohort. The Monash Chart, but none of the existing charts, accurately determined gestational age among an independent IVF twin cohort (185 twin pairs). When applied to 3052 naturally-conceived singletons scans, The Monash Chart generated estimated due dates that were different to all existing charts (P≤0.004 all comparisons). We conclude that commonly used ultrasound reference charts have inaccuracies. We have generated a CRL reference chart based on true gestational age in an IVF cohort that can accurately determine gestational age at 6–9 weeks of gestation.

1969 ◽  
Vol 47 (15) ◽  
pp. 2739-2746 ◽  
Author(s):  
J. C. MacDonald

The optical rotation of various concentrations of L-valine and L-leucine, dissolved in glacial acetic acid, or 5 or 6 M HCl, was measured with a photoelectric polarimeter at the nominal wavelengths 589, 578, 546, 436, and 365 nm and temperatures of 20, 25, and 30 °C. The specific rotation for any one wavelength, solute, and solvent could be defined by the equation [α]λT = A(1 + D(T − 25)) + BC, where T is temperature in °C, C is concentration in grams of solute per 100 ml of solution, and A, B, and D are constants. The best fit values of the constants were determined by computer calculation and are listed. Constants are also given for calculating a specific rotation based on grams of solute per 100 g of solution.


2012 ◽  
Vol 6 (2) ◽  
pp. 27-32
Author(s):  
Folorunsho B Adewale ◽  
Munir'deen A Ijaiya

Aims: Accurate determination of gestational age (GA) is an important part of obstetric care. The aim of this study is to determine the reliability of Symphsio-Fundal Height (SFH) measurement in assessing Gestational Age in the second half of pregnancy. Methods: A total of 390 pregnant Nigerian women carrying uncomplicated singleton pregnancies between the gestational age of 20-40 weeks had SFH measurements done at the antenatal clinic, and ultrasonic biparietal diameter (BPD) and femur length (FL) determination at the fetal assessment unit, maternity wing of the University of Ilorin Teaching Hospital, Ilorin, Nigeria. The patients were followed up subsequently and managed till delivery. At delivery each baby was examined within the first 48 hours of life and gestational age at birth was assigned using the Ballard method. Results: Of the 390 patients studied, SFH correctly assessed GA in 80% compared to 81.3% for BPD (P = 0.43), 82.1% for FL (P – 0.41), 84.1% for BPD and FL (p = 0.35. There is no significant difference in the sensitivity of SFH 93.1% and ultrasound 97.9%. There is also no significant difference in the margin of error between the true gestational ages obtained by the two methods (SFH 15-41days Vs ultrasound 15-33days). Combined ultrasound parameters(BP & FL),FL, BPD and SFH were progressively less closely correlated with the Ballard age of the fetus.Conclusions: This study showed that accurate measurement of the SFH is a reliable method of gestational age assessment in the second half of pregnancy.NJOG 2011 Nov-Dec; 6 (2): 27-32 DOI: http://dx.doi.org/10.3126/njog.v6i2.6753


2021 ◽  
Author(s):  
Nathan Brown ◽  
Edward Rhodes

Luminescence thermochronology and thermometry can quantify recent changes in rock exhumation rates and rock surface temperatures, but these methods require accurate determination of several kinetic parameters. For K-feldspar thermoluminescence (TL) glow curves, which comprise overlapping signals of different thermal stability, it is challenging to develop measurements that capture these parameter values. Here, we present multiple-aliquot additive-dose (MAAD) TL dose response and fading measurements from bedrock-extracted K-feldspars. These measurements are compared with Monte Carlo simulations to identify best-fit values for recombination center density ($\rho$) and activation energy ($\Delta E$). This is done for each dataset separately, and then by combining dose-response and fading misfits to yield more precise $\rho$ and $\Delta E$ values consistent with both experiments. Finally, these values are used to estimate the characteristic dose ($D_0$) of samples. This approach produces kinetic parameter values consistent with comparable studies and results in expected fractional saturation differences between samples.


2018 ◽  
Vol 87 (4) ◽  
pp. 357-362 ◽  
Author(s):  
Mushap Kuru ◽  
Hasan Oral ◽  
Recai Kulaksiz

The aim of this study was to determine gestational age in Abaza and Gurcu goats by measuring certain embryonic and foetal indices with ultrasonography. A 5–7.5 MHz linear probe was used to obtain ultrasound measurements from 30 pregnant goats (10 Abaza and 20 Gurcu). Heart diameter (HD), biparietal diameter (BPD), crown-rump length (CRL), trunk diameter (TD) and placentome diameter (PD) were measured to determine gestational age. The mean of embryonic and foetal indices were calculated and linear regression was performed. Heart diameter measurements for Abaza and Gurcu goats were significantly different on days 45 (P= 0.048) and 60 (P= 0.019). Biparietal diameter values were significantly different on day 45 (P= 0.035). Crown-rump length measurements were significantly different at days 30 (P= 0.003) and 60 (P= 0.002). We determined that HD and TD were the best predictors of gestational age for Abaza goats (R2= 0.952, R2= 0.949, respectively), whereas HD and CRL were the best predictors of gestational age for Gurcu goats (R2= 0.933, R2= 0.942, respectively). Based upon our study results, these specific indices could be applied during ultrasonographic examinations of Abaza and Gurcu goats to confirm gestational age when the day of mating is unknown.


2014 ◽  
Vol 27 (1) ◽  
pp. 42 ◽  
Author(s):  
Raquel Bastos ◽  
Carla Ramalho ◽  
Sofia Dória

<strong>Introduction:</strong> Spontaneous abortion is one of the most frequent problems of pregnancy, estimated to affect, at least, one in every four women who tries to conceive. The main purpose of this work was to study the prevalence of chromosomal abnormalities in gestational losses, evaluating their relation with maternal age, gestational age and previous abortion history.<br /><strong>Material and Methods:</strong> Retrospective study of 401 pregnancy loss cases that have gone through cytogenetic and anatomopathologic analysis between January 2008 and June 2012, in Centro Hospitalar de S. João, Oporto.<br /><strong>Results:</strong> Of the 401 cases sent to cytogenetic study, it was possible to obtain information about the chromosomal complement in 333 cases, of which 72.7% showed normal karyotype, and 27.3% abnormal karyotype. Aneuploidies represented 92.3% of the identified chromosomopathies, with trisomies being the most frequent, related with an advanced maternal age and an early gestational age. There was no agreement between the results of the cytogenetic and the anatomopathologic analysis.<br /><strong>Discussion/Conclusion: </strong>The prevalence of chromosomal abnormalities, during the first trimester, is similar between sporadic and recurrent miscarriages. With increased maternal age, trisomies, the most frequent type of aneuploidy, are more likely to occur, with a mean increment in probability of 7.4% per year. A significant karyotype-pathological correlation was not established. Maternal contamination is the main obstacle to the accurate determination of the prevalence of chromosomal abnormalities. The molecular cytogenetic techniques already available can overcome the limitations of the conventional technique.


2016 ◽  
Vol 3 (1) ◽  
pp. 37-48
Author(s):  
Mirta M Aliendo ◽  
Emanuel Repetto

En la etapa fetal se observa un rápido incremento de la masa corporal y de todas las dimensiones. La literatura evidencia discrepancias sobre los criterios para determinar el estadio fetal post-mortem, en relación a los parámetros morfométricos utilizados, por lo que nuestro objetivo fue comparar la medición morfológica directa (vertex-coxis, tabla de Hansmann) con la ultrasonografía (medición del fémur), para establecer el grado de confiabilidad en la determinación post-mortem del estadío fetal. Se utilizaron 120 fetos: 1) grupo A (60 fetos) estadificado ecográficamente y 2) grupo B (60 fetos) estadificado por tabla de Hansmann. A ambos grupos se le realizaron múltiples mediciones siguiendo parámetros probados según la literatura internacional. Se utilizó calibre de precisión. Parámetros evaluados: longitud vertex-coxis, circunferencia cefálica, diámetro cefálico occipito-frontal, biparietal, longitud mentón-vertex, perímetro toráxico-transverso, circunferencia abdomi-nal y longitudes de brazo, antebrazo, mano, muslo, pierna y pie. Estos valores fueron agrupados por semanas, obteniéndose la media y aplicándose la prueba t de Student. Los resultados demostraron que la diferencia entre los parámetros medidos en el grupo A y en el grupo B eran significativas en todas las semanas, por lo que se observa disparidad en la determinación del estadio fetal por ecografía y los registros correspondientes a la medición vertex-coxis (tabla de Hansmann) postmortem. Concluímos que los resultados obtenidos por ambas modalidades de medición son diferentes para una misma edad gestacional y, por ende, resultaría más apropiado referirse a fetos con ciertas dimensiones según alguno de estos parámetros que a “edad gestacional”.In fetal stage, body mass and measurements quickly increase. Scientific literature shows differences on the criteria to determine the post-mortem fetal stage, depending on morphometric parameters. Our objective was to compare both methods, direct morphologic measures (crown-rump length, Hansmann table) and ultrasonography (femur measurement), to establish their reliability on post-mortem determination of fetal age. One hundred and twenty fetuses were studied: 1) group A (60 fetuses) sonographically staged and 2) group B (60 fetuses) staged according to Hansmann table. Many measurements were performed on both groups, following internationally determined parameters. We used a precision gauge. Considered parameters were: crown-rump length, head circumference, occipito-frontal diameter, bi-parietal length, chin-vertex length, thoracic transverse perimeter, abdominal circumference, arm, forearm, hand, thigh, leg and foot lengths. Obtained information was grouped by weeks. We calculated the data mean and significant difference was managed by Student t-test. Results demonstrated significant difference in the considered parameters between group A and B, and then, to determine the fetal age.We conclude that results obtained by both measuring modalities were different for the same gestational age, and therefore, it should be more appropriate to consider fetuses by measures obtained following certain parameters than by “gestational age”.


2012 ◽  
Vol 39 (4) ◽  
pp. 761-765 ◽  
Author(s):  
Kanika Chaudhuri ◽  
Lin-Lin Su ◽  
Peng-Cheang Wong ◽  
Yiong-Huak Chan ◽  
Mahesh A. Choolani ◽  
...  

2013 ◽  
Vol 26 (1) ◽  
pp. 3-9
Author(s):  
Folorunsho B Adewale ◽  
Munir’deen A Ijaiya

Background: Accurate determination of gestational age (GA) is an important part of obstetric care. Objective: The aim of this study is to determine the reliability of symphsio-fundal height (SFH) measurement in assessing gestational age in the second half of pregnancy.Method: A total of 390 pregnant Nigerian women carrying uncomplicated singleton pregnancies between the gestational age of 20-40 weeks had SFH measurements done at the antenatal clinic, and ultrasonic biparietal diameter (BPD) and femur length (FL) determination at the fetal assessment unit, maternity wing of the University of Ilorin Teaching Hospital, Ilorin, Nigeria. The patients were followed up subsequently and managed till delivery. At delivery each baby was examined within the first 48 hours of life and gestational age at birth was assigned using the Ballard method. Result: Of the 390 patients studied, SFH correctly assessed GA in 80% compared to 81.3% for BPD (P = 0.43), 82.1% for FL (P = 0.41), 84.1% for BPD and FL (p = 0.35). There is no significant difference in the sensitivity of SFH 93.1% and ultrasound 97.9%. There is also no significant difference in the margin of error between the true gestational ages obtained by the two methods (SFH 15-41days Vs ultrasound 15-33days). Combined ultrasound parameters(BP & FL),FL, BPD and SFH were progressively less closely correlated with the age of the fetus assessed by Ballard method. Conclusion: This study showed that accurate measurement of the SFH is a reliable method of gestational age assessment in the second half of pregnancy DOI: http://dx.doi.org/10.3329/bjog.v26i1.13751 Bangladesh J Obstet Gynaecol, 2011; Vol. 26(1) : 3-9


Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as


Author(s):  
M.A. Gribelyuk ◽  
M. Rühle

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.


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