1,356,354 research outputs found
Ultrasound in placental disorders
No full textThe definition of placenta previa based on ultrasound findings is more practical, and the traditional definition (implantation of the placenta in the lower uterine segment) needs to be revised. The term 'placenta previa' should only be used when the placental edge overlaps or is within 2 cm of the internal cervical orifice in late pregnancy. If the placental edge is located further than 2 cm but within 3.5 cm from the internal cervical orifice, the placenta should be termed 'low-lying'. Unless the placental edge at least reaches the internal orifice at mid-trimester, symptomatic placenta previa in the third trimester will not be encountered. Caesarean section is the recommended mode of delivery for placenta previa at term. Attempt at vaginal delivery is appropriate for low-lying placenta, but the possibility of post-partum haemorrhage should be kept in mind. The incidence of invasive placentation, such as placenta accrete, has progressively risen in the past 3 decades, possibly as a consequence of increasing caesarean section rates. Ultrasound has a sensitivity of 91% and a specificity of 97% for the identification of all forms of invasive placentation. Chorioangiomas are benign non-trophoblastic placental tumours with excessive vascular proliferation within the stroma of chronic villi. They are usually asymptomatic, although occasionally can be associated with adverse fetal outcomes. Chorioangiomas usually appear as well-circumscribed, rounded, hypo-echoic lesions next to the chorionic surface. Iatrogenic delivery or prenatal intervention are two options, if fetal compromise is present. Prenatal detection leads to a dramatic increase in survival compared with those cases unsuspected antenatally
A survey of current clinical practice of chorionic villus sampling
No full textObjective
The number of invasive procedures (chorionic villus sampling (CVS) or amniocentesis) for fetal testing is decreasing because of the availability of non‐invasive prenatal test (NIPT) leading to a centralisation of prenatal diagnostic services to accredited fetal medicine centres. A new survey was conducted 10 years after the previous one to update the current clinical practice among clinicians who regularly perform CVS.
Method
Consultants from 32 centres in the United Kingdom were invited to take part in an online survey evaluating: The total number of CVS procedures carried out in the unit in a typical week, the preferred route (transabdominal [TA] vs transcervical [TC]), technique (use of local anaesthetic [LA] and needle technique).
Results
Response rate was 96.9%; TA was the preferred route (96.8%) in all centres except one. Single‐needle technique is used exclusively in half the centres (51.6%). LA is used by most operators (90.3%) before the procedure. Three centres did not routinely use LA for CVS.
Conclusions
Operators across the United Kingdom almost exclusively use the TA route for CVS with single‐needle technique in 51.6% of cases. The use of LA prior to CVS is a very common practice in the United Kingdom
X-ray spectroscopic study of zirconium and molybdenum diselenides
No full textThe k absorption spectra of zirconium, molybdenum and selenium in ZrSe2 and MoSe2 have been recorded photographically using a Cauchois type bent crystal (mica) spectrograph. The absorption edge shifts are used along with the data for NbSe2 (Bhide and Bahl 1971J. Phys. Chem. Solids 32 1001) to propose bond schemes for these compounds
Early- and late-onset selective fetal growth restriction in monochorionic diamniotic twin pregnancy: natural history and diagnostic criteria
No full textObjectives: To evaluate the natural history and outcome of selective fetal growth restriction (sFGR) in monochorionic diamniotic (MCDA) twin pregnancy, according to gestational age at onset and various reported diagnostic criteria, and to quantify the risk of superimposed twin-to-twin transfusion syndrome (TTTS). Methods: This was a cohort study of MCDA twin pregnancies that had their routine antenatal care from the first trimester at St George's Hospital, London, UK. Pregnancies had ultrasound examinations every 2 weeks at 16–24 weeks and then every 2–3 weeks until delivery. The diagnostic criteria for sFGR were estimated fetal weight (EFW) of one twin < 10th centile and intertwin EFW discordance ≥ 25%. We also applied other diagnostic criteria reported in a recent Delphi consensus. Pregnancies in which the diagnosis of TTTS was made before that of sFGR were not included in the analysis. Pregnancies that underwent fetal intervention for sFGR were excluded. The incidence of sFGR was compared between the different diagnostic criteria, overall and according to gestational age at onset. In all subsequent analyses, cases of sFGR included those diagnosed according to any of the criteria. The Gratacós classification of sFGR was applied (Type I, II or III). Pregnancy outcomes included miscarriage, intrauterine death, neonatal death and admission to the neonatal unit. Comparisons between groups were carried out using the Mann–Whitney U-test for continuous variables and the chi-square or Fisher's exact test for categorical variables. Results: The analysis included 287 MCDA twin pregnancies. According to the International Society of Ultrasound in Obstetrics and Gynecology diagnostic criteria, the incidence of early (< 24 weeks) sFGR was 4.9%, while that of late sFGR was 3.8%. When applying the various diagnostic criteria, the incidence of early sFGR varied from 1.7% to 9.1% and that of late sFGR varied from 1.1% to 5.9%. In early-onset cases, the incidence of Type I sFGR was 80.8%, that of Type II was 15.4% and that of Type III was 3.8%. The corresponding figures in late-onset cases were 94.4%, 5.6% and 0%. The incidence of superimposed TTTS was 26.9% in cases affected by early-onset sFGR and 5.6% in those affected by late-onset sFGR. The incidence of perinatal death was 8.0% in early-onset sFGR and 5.6% in late-onset sFGR (P = 0.661). Admission to the neonatal unit occurred in 61.0% and 52.9% of cases, respectively (P = 0.484). Conclusions: In MCDA twin pregnancies, early-onset sFGR is slightly more common than is late-onset sFGR, although this difference was not significant, and is associated with worse perinatal outcome. The incidence of Types II and III sFGR is higher in early-onset sFGR. The incidence also varies according to the diagnostic criteria used, which supports the use of standardized international diagnostic criteria. Superimposed TTTS is more common in early- than in late-onset sFGR. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd
Association of uterine artery Doppler resistance index and birth weight: Effect of customized birth weight standards
No full textWe assessed the effect of using customized birth-weight standards on the association of uterine artery Doppler resistance index (RI) and birth weight. This was a cross-sectional study of 2035 pregnancies scanned at 19 to 23 weeks. Both uterine arteries were identified using color flow mapping, and the RI was measured. The pregnancy outcome was obtained from the delivery suite database and the customized birth-weight centile calculated for each pregnancy. Both birth-weight and customized birth-weight centiles were converted to z-scores. The correlation of uterine artery RI with birth weight was examined using conventional and customized birth-weight standards. Conventional and customized birth weights showed a significant correlation with uterine artery RI (r = -0.062 and -0.208, respectively). The correlation was significantly improved by the use of customized birth weight. Use of customized birth weight significantly improves the correlation of uterine artery RI and birth weight. This finding may partly explain the lower sensitivity of uterine artery Doppler screening for fetal growth restriction as compared with preeclampsia. Copyright © 2009 by Thieme Medical Publishers, Inc
Perinatal and long-term outcome in fetuses diagnosed with isolated unilateral ventriculomegaly: systematic review and meta-analysis.
No full textOBJECTIVES: The majority of the studies have focused on the perinatal and long-term outcomes in fetuses with antenatal diagnosis of bilateral ventriculomegaly. The aim of this study was to undertake a systematic review and meta-analysis to quantify the perinatal and long-term outcome of fetuses diagnosed with isolated unilateral ventriculomegaly during the second- or third- trimester of pregnancy. METHODS: Medline, and Embase and The Cochrane Library were searched electronically. The outcomes investigated included incidence of aneuploidy, congenital infections, progression, associated brain and extra-brain abnormalities for the apparently isolated unilateral ventriculomegaly cases and neurodevelopmental delay for both apparently and truly isolated unilateral ventriculomegaly cases. Sensitivity analysis was performed according to whether the ventriculomegaly was mild or severe. Reference lists of relevant articles and reviews were hand-searched for additional reports. Cohort and case-control studies were included. Meta-analyses of proportions were used. Between-study heterogeneity was assessed using the I(2) test. RESULTS: The search yielded 2053 citations. Full text was retrieved for 202 and the 11 studies were included in the systematic review. In fetuses with apparently isolated unilateral ventriculomegaly there were no chromosomal abnormalities and the rate of congenital infections was 8.2% (95% CI 3.6-14.5). The prevalence of MRI-detected additional brain abnormalities prenatally and postnatally was 5% (95% CI, 0.2-16) and 6.4%, (95% CI, 0.3-19.4), respectively. The incidence of abnormal neurodevelopmental status in apparently isolated cases measuring <15 mm was 5.9% (95% CI, 2.2-11.2), while it was 7.0% (95% CI, 3.2-12.2) in fetuses with truly isolated unilateral ventriculomegaly. Most of the cases reported (93%) were mild ventriculomegaly, and therefore the outcomes were similar to those above. CONCLUSIONS: The prevalence of aneuploidy, congenital infections and neurodevelopmental delay in fetuses with a prenatal diagnosis of isolated unilateral ventriculomegaly is likely to be low
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Prevalence of maternal cardiac defects in women with high-resistance uterine artery Doppler indices.
No full textObjectives: To compare the prevalence of previously undiagnosed cardiac structural abnormalities in pregnant women with normal- and high-resistance midtrimester uterine artery Doppler indices. Methods: Maternal transthoracic echocardiography was undertaken in asymptomatic pregnant women after uterine artery Doppler screening for pre-eclampsia at 21-23 weeks' gestation. Women with a mean uterine artery pulsatility index above the 90 th centile (1.25) for the local population (multiethnic, socially diverse and migrant) were considered to have high-resistance uteroplacental blood flow indices. The prevalence of newly diagnosed cardiac structural defects in these women was recorded. Results: A total of 491 women underwent echocardiography, of whom 205 had high-resistance uterine artery blood flow indices. There were nine previously undiagnosed, functionally significant cardiac defects in the high-resistance uterine artery blood flow group and only one, functionally insignificant cardiac defect in the normal-resistance group (P = 0.005; relative risk = 12.6, 95% confidence interval, 1.60-98.34). Multiple regression analysis demonstrated that both uterine artery Doppler indices (P = 0.024) and ethnicity (P = 0.048) contributed independently towards a higher prevalence of cardiac defects. Conclusions: The prevalence of previously undiagnosed maternal cardiac structural abnormalities is significantly increased in women with high midtrimester uterine artery Doppler resistance indices. This observation has important consequences for the current and longterm medical care provided to these patients. Detailed maternal cardiac assessment with echocardiography may be required in migrant women with high uterine artery Doppler indice
Botulinum neurotoxin type A injection of the pelvic floor muscle in pain due to spasticity: a review of the current literature.
No full textThe role of muscle spasm is not a new concept in the genesis of pain. Botulinum neurotoxin type A (BoNTA) has been successfully employed in a variety of muscular and inflammatory conditions. The aim of our study was to review the published literature on the role of BoNTA injection of the pelvic floor muscle in the management of women with chronic pelvic pain (CPP). A systematic search of the literature published up to June 2012 on the use of BoNTA in the treatment of female pelvic floor muscle spasm was carried out using relevant search terms in MEDLINE and EMBASE databases. The results were limited to full-text English language articles. Relevant trials as well as relevant reviews were selected and analyzed by two independent reviewers. Five studies (2 case reports, 1 prospective pilot study, 1 retrospective study and 1 randomised double-blind placebo controlled study) were included in this systematic review. Overall, BoNTA has shown to be beneficial in relieving CPP related to pelvic floor spasm. The role of BoNTA as a treatment of CPP has been recognized for more than 10 years. Although data are still scarce preliminary results are encouraging. BoNTA is an attractive option for refractory CPP related to pelvic floor muscle spasm, but further studies using validated and reproducible outcome measures are needed, to establish its effectiveness, safeness, technique, optimal dosage, and duration of symptom relief
Mid pregnancy fetal growth, uteroplacental doppler indices and maternal demographic characteristics: role in prediction of stillbirth.
No full textINTRODUCTION: To evaluate the relative value of mid trimester fetal growth, uterine artery (UtA) Doppler indices and maternal demographics in prediction of stillbirth. MATERIAL AND METHODS: Retrospective cohort study; 23,894 singleton pregnancies routinely scanned between 19 and 24 weeks' gestation. Maternal characteristics included age, body mass index, ethnicity and medical history. Fetal biometry indices, birthweight and UtA pulsatility index (PI) values were converted to percentiles and multivariable logistic regression analysis was performed. The predictive accuracy was assessed using ROC curves analysis. The main outcome was prediction of preterm and term stillbirths. RESULTS: Non-Caucasian ethnicity, femur length centile and UtA PI were significantly associated with the risk of stillbirth (all p <0.01). The detection rate of screening by maternal factors alone was 19% for all stillbirths, and 12% and 14% for term and preterm stillbirth at a 10% false positive rate; using femur length centile alone the detection rates were 27% and 23% respectively. UtA PI alone was able to predict 24% and 31% of term and preterm stillbirths. Screening by combining maternal factors, femur length centile and UtA Doppler detected 27% and 35% of term and preterm stillbirths at a 10% false positive rate. CONCLUSIONS: Second trimester ultrasound assessment offers an opportunity to identify pregnancies at the highest risk of stillbirth occurring as a consequence of placental dysfunction. This information may be useful to improve pregnancy outcome by identifying women who may benefit from increased ultrasound surveillance and/or timely intervention. This article is protected by copyright. All rights reserved
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