Background Women with a history of previous cesarean delivery, presenting with a placenta previa, have become the largest group with the highest risk for placenta previa accreta. Objective The ...objective of the study was to evaluate the accuracy of ultrasound imaging in the prenatal diagnosis of placenta accreta and the impact of the depth of villous invasion on management in women presenting with placenta previa or low-lying placenta and with 1 or more prior cesarean deliveries. Study Design and Data Sources We searched PubMed, Google Scholar, clinicalTrials.gov , and MEDLINE for studies published between 1982 and November 2016. Study Eligibility Criteria Criteria for the study were cohort studies that provided data on previous mode of delivery, placenta previa, or low-lying placenta on prenatal ultrasound imaging and pregnancy outcome. The initial search identified 171 records, of which 5 retrospective and 9 prospective cohort studies were eligible for inclusion in the quantitative analysis. Study Appraisal and Synthesis Methods The studies were scored on methodological quality using the Quality Assessment of Diagnostic Accuracy Studies tool. Results The 14 cohort studies included 3889 pregnancies presenting with placenta previa or low-lying placenta and 1 or more prior cesarean deliveries screened for placenta accreta. There were 328 cases of placenta previa accreta (8.4%), of which 298 (90.9%) were diagnosed prenatally by ultrasound. The incidence of placenta previa accreta was 4.1% in women with 1 prior cesarean and 13.3% in women with ≥2 previous cesarean deliveries. The pooled performance of ultrasound for the antenatal detection of placenta previa accreta was higher in prospective than retrospective studies, with a diagnostic odds ratios of 228.5 (95% confidence interval, 67.2–776.9) and 80.8 (95% confidence interval, 13.0–501.4), respectively. Only 2 studies provided detailed data on the relationship between the depth of villous invasion and the number of previous cesarean deliveries, independently of the depth of the villous invasion. A cesarean hysterectomy was performed in 208 of 232 cases (89.7%) for which detailed data on management were available. Positive correlations were found in the largest prospective studies between the cumulative rates of the more invasive forms of accreta placentation and the sensitivity and specificity of ultrasound imaging but not with diagnostic odds ratio values. We found no data on the ultrasound screening of placenta accreta at the routine midtrimester ultrasound examination from the nonexpert ultrasound units. Conclusion Planning individual management for delivery is possible only with accurate evaluation of prenatal risk of accreta placentation in women presenting with a low-lying placenta/previa and a history of prior cesarean delivery. Ultrasound is highly sensitive and specific in the prenatal diagnosis of accreta placentation when performed by skilled operators. Developing a prenatal screening protocol is now essential to further improve the outcome of this increasingly more common major obstetric complication.
Many warn that the next stage of globalization--the offshoring of research and development to China and India--threatens the foundations of Western prosperity. But in The Venturesome Economy, ...acclaimed business and economics scholar Amar Bhidé shows how wrong the doomsayers are. Using extensive field studies on venture-capital-backed businesses to examine how technology really advances in modern economies, Bhidé explains why know-how developed abroad enhances--not diminishes--prosperity at home, and why trying to maintain the U.S. lead by subsidizing more research or training more scientists will do more harm than good.
Keynes thought it would be 'splendid' if economists became more like dentists. Disciplinary economics has instead become more like physics in focusing on concise, universal propositions verified ...through decisive tests. This focus, I argue, limits the practical utility of the discipline because universal propositions form only a part of new policy recipes. I further suggest that, as in engineering and medicine, developing economic recipes requires eclectic combinations of suggestive tests and judgement. Additionally, I offer a detailed example of how a simulation model can help evaluate new policy combinations that affect the screening of loan applications.
Rules that restrict information required in negotiated private transactions have spurred a vast increase in the scope of anonymous financial markets, particularly in the United States. The subtle ...costs of the information‐restricting rules raise questions about the social value of “completing” anonymous markets that would not naturally survive and did not historically exist.
Objective We sought to evaluate the association between fetal cerebroplacental ratio (CPR) and intrapartum fetal compromise and admission to the neonatal unit (NNU) in term pregnancies. Study Design ...This was a retrospective cohort study in a single tertiary referral center over a 14-year period from 2000 through 2013. The umbilical artery pulsatility index, middle cerebral artery pulsatility index, and CPR were recorded within 2 weeks of delivery. The birthweight (BW) values were converted into centiles and Doppler parameters converted into multiples of median (MoM), adjusting for gestational age using reference ranges. Logistic regression analysis was performed to identify, and adjust for, potential confounders. Results The study cohort included 9772 singleton pregnancies. The rates of operative delivery for presumed fetal compromise and neonatal admission were 17.2% and 3.9%, respectively. Doppler CPR MoM was significantly lower in pregnancies requiring operative delivery or admission to NNU for presumed fetal compromise ( P < .01). On multivariate logistic regression, both CPR MoM and BW centile were independently associated with the risk of operative delivery for presumed fetal compromise (adjusted odds ratio OR, 0.67; 95% confidence interval CI, 0.52–0.87; P = .003 and adjusted OR, 0.994; 95% CI, 0.992–0.997; P < .001, respectively). The latter associations persisted even after exclusion of small-for-gestational-age cases from the cohort. Multivariate logistic regression also demonstrated that CPR MoM was an independent predictor for NNU admission at term (adjusted OR, 0.55; 95% CI, 0.33–0.92; P = .021), while BW centile was not (adjusted OR, 1.00; 95% CI, 0.99–1.00; P = .794). The rates of operative delivery for presumed fetal compromise were significantly higher for appropriate-for-gestational-age fetuses with low CPR MoM (22.3%) compared to small-for-gestational-age fetuses with normal CPR MoM (17.3%). Conclusion Lower fetal CPR, regardless of the fetal size, was independently associated with the need for operative delivery for presumed fetal compromise and with NNU admission at term. The extent to which fetal hemodynamic status could be used to predict perinatal morbidity and optimize the mode of delivery merits further investigation.
Non-medical innovation has become progressively more open, harnessing the enterprise and creativity of a variety of players (including venturesome consumers) and relying on diverse structured and ...unstructured methods to generate and select advances. Medical innovation, however, remains more closed and regimented because of age-old traditions, reinforced by modern funding and regulatory practices that require the costly ex-ante demonstration of efficacy. These practices, which seek to replicate those of the natural sciences, militate against the pluralistic creation and use of medical innovations and suppress ad-hoc, accretive-and potentially life-saving-advances.
Abstract Background The cerebroplacental ratio has been proposed as a marker of failure to reach growth potential near term. Low cerebroplacental ratio, regardless of the fetal size, is independently ...associated with the need for operative delivery for presumed fetal compromise and with neonatal unit admission at term. Objective The main aim of this study was to evaluate whether the cerebroplacental ratio at term is a marker of reduced fetal growth rate. The secondary aim was to investigate the relationship between low cerebroplacental ratio at term, reduced fetal growth velocity and adverse pregnancy outcome. Design: retrospective cohort study of singleton pregnancies in a tertiary referral center. The abdominal circumference was measured at 20-24 weeks’ gestation, and both abdominal circumference and fetal Dopplers recorded at or beyond 35 weeks, within two weeks of delivery. Abdominal circumference and birthweight values were converted into Z scores and centiles, respectively, and fetal Doppler parameters into multiples of median, adjusting for gestational age. Abdominal circumference growth velocity was quantified using the difference in abdominal circumference Z score, comparing the scan at or beyond 35 weeks with the scan at 20-24 weeks. Both univariable and multivariable logistic regression analyses were performed to investigate the association between low cerebroplacental ratio, low abdominal circumference growth velocity (in the lowest decile), and to identify and adjust for potential confounders. As a sensitivity analysis, we refitted the model excluding the data on pregnancies with small for gestational age neonates. Results The study included 7944 pregnancies. Low cerebroplacental ratio multiples of median was significantly associated with both low abdominal circumference growth velocity (adjusted OR 2.10; 95%CI 1.71-2.57, p<0.001) and small for gestational age (adjusted OR 3.60; 95%CI 3.04-4.25, p<0.001). After the exclusion of pregnancies resulting in small for gestational age neonates, low cerebroplacental ratio multiples of median remained significantly associated with both low abdominal circumference growth velocity (adjusted OR 1.76; 95%CI 1.34-2.30, p<0.001) and birthweight centile (adjusted OR 0.99; 95%CI 0.998-0.995, p<0.001). The need for operative delivery for fetal compromise was significantly associated with low cerebroplacental ratio (adjusted OR 1.40; 95%CI 1.10-1.78, p=0.006), even after adjusting for both the umbilical artery pulsatility index multiples of median and middle cerebral artery pulsatility index multiples of median. The results were similar even after the exclusion of pregnancies resulting in small for gestational age neonates (adjusted OR 1.39; 95%CI 1.06-1.84, p=0.018). Low cerebroplacental ratio multiples of median remained significantly associated with the risk of operative delivery for presumed fetal compromise (p<0.001), even after adjusting for the known antenatal and intrapartum risk factors. These associations persisted even after exclusion of small for gestational age births. In appropriate for gestational age sized fetuses, abdominal circumference growth velocity was significantly lower in those with low cerebroplacental ratio multiples of median than in those with normal cerebroplacental ratio multiples of median (p<0.001). Conclusion Cerebroplacental ratio is a marker of impaired fetal growth velocity and adverse pregnancy outcome, even in fetuses whose size is considered appropriate using conventional biometry.
Objective Fetal cerebroplacental ratio is emerging as a better proxy than birthweight for placental insufficiency and as a marker of fetal compromise at term. The extent to which these fetal Doppler ...changes are related to neonatal outcomes has not been systematically assessed. The main aim of this study was to evaluate the association between estimated fetal weight percentile, cerebroplacental ratio recorded at 34+0 –35+6 weeks’ gestation, and neonatal unit admission at term. Study Design This was a retrospective cohort study in a tertiary referral center over an 11 year period from 2002 to 2012. The umbilical artery pulsatility index (PI), middle cerebral artery PI, and cerebroplacental ratio were recorded at 34+0 –35+6 weeks. Weight values were converted into percentiles and Doppler parameters into multiples of the median (MoM), adjusting for gestational age. Logistic regression analysis was performed to identify, and adjust for, potential confounders. Results We identified 2518 pregnancies in which a scan was performed at 34+0 –35+6 weeks and delivery occurred at or beyond 37 weeks. In the 2485 pregnancies included in the analysis, the umbilical artery PI MoM was significantly higher, and the middle cerebral artery PI and cerebroplacental ratio MoM significantly lower in the babies requiring neonatal unit admission ( P < .05). However, the estimated fetal weight percentile was not significantly different between those who required neonatal unit admission and those who did not ( P = .087). According to multivariate logistic regression, cerebroplacental ratio MoM (odds ratio, 0.39; 95% confidence interval, 0.19–0.79; P = .008) and gestational age at delivery (odds ratio, 0.70; 95% confidence interval, 0.61–0.80; P < .001) were significantly associated with the risk of neonatal unit admission, whereas maternal age and birthweight percentile were not ( P = .183 and P = .460, respectively). Irrespective of birthweight or estimated fetal weight percentile, the fetal cerebroplacental ratio appears to be a better predictor of the need for neonatal unit admission ( P < .001). Conclusion Lower cerebroplacental ratio and gestational age at delivery, but not fetal size, were independently associated with the need for admission to the neonatal unit at term in a high-risk patient group. The extent to which fetal hemodynamic assessment could be used to predict perinatal morbidity and optimize the timing of delivery merits further investigation.
In a field dominated by anecdote and folklore, this landmark study integrates more than ten years of intensive research and modern theories of business and economics. The result is a comprehensive ...framework for understanding entrepreneurship that provides new and penetrating insights. This clearly and concisely written book is essential for anyone who wants to start a business, for the entrepreneur or executive who wants to grow a company, and for the scholar who wants to understand this crucial economic activity.
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