Real-time ultrasound demonstration of uterine isthmus contractions during pregnancy.

BACKGROUND: Asymptomatic isthmic contractions are a frequent physiological phenomenon in pregnancy, sometimes triggered by bladder voiding. They can interfere with proper cervical length assessment and may lead to false images of placenta previa. However, there is limited research on the prevalence and characteristics of these contractions. OBJECTIVE: This study aimed to determine the prevalence and characteristics of isthmic contractions after bladder voiding in the second trimester of pregnancy, to evaluate their effect on cervical length assessment, and to propose a new method for the objective assessment of the presence and intensity of isthmic contractions. STUDY DESIGN: In this prospective observational study, long videos of the uterine cervix were recorded in 30 singleton pregnancies during the second trimester of pregnancy after bladder voiding. Isthmic length and cervicoisthmic length changes were assessed over time. The isthmic length was measured using a new approach, which involved calculating the distance from the base of the cervix to the internal os, including the isthmus. RESULTS: Isthmic contractions were observed in 43% of pregnant women (95% confidence interval, 26%-62%) after bladder voiding. The median time for complete isthmus relaxation was 19.7 minutes (95% confidence interval, 15.0 to not available). No substantial differences in maternal characteristics were found between individuals with and without contractions. The proposed method for measuring isthmic length provided an objective assessment of the presence and intensity of isthmic contractions. A cutoff of 18 mm in isthmic length allowed for the distinction of pregnant women presenting a contraction. In addition, the study identified a characteristic undulatory pattern in the relaxation of the isthmus in half of the cases with contractions. CONCLUSION: Isthmic contractions are a common occurrence after bladder voiding in the second trimester of pregnancy and may interfere with proper cervical length assessment. We recommend performing cervical assessment at least 20 minutes after bladder voiding to reduce the risk of bias in cervical length measurement and to avoid false images of placenta previa. The new method for measuring isthmic length provides an objective way to assess the presence and intensity of isthmic contractions. Further research is needed to understand the role of isthmic contractions in the physiology of pregnancy and birth.

Array study in fetuses with nuchal translucency above the 95th percentile: a 4-year observational single-centre study.

PURPOSE: To evaluate the performance of chromosomal microarray analysis (CMA) in fetuses with nuchal translucency (NT) > 95th percentile. Secondary objectives were to analyze these results according to NT thickness, below or above 3.5 mm, and those without associated anomalies. METHODS: This observational single-cohort study was conducted between 2015 and 2018 in fetuses with NT > 95th percentile. Following an invasive test, quantitative fluorescence-polymerase chain reaction (QF-PCR) was performed, and if normal, CMA was performed. Pathogenic copy number variants (CNVs), non-reported pathogenic CNV, pathogenic autosomal recessive variants and variants of unknown significance (VUS) were analysed. RESULTS: One-hundred and sixty-two fetuses with NT > 95th percentile, normal QF-PCR and CMA were included. Amongst 128 fetuses with NT between the 95th percentile and 3.5 mm, one (0.8%) had a pathogenic CNV, four (3.1%) had non-reported pathogenic CNV, one (0.8%) had pathogenic autosomal recessive variant and 13 (10.2%) had VUS. Amongst 34 fetuses with NT ≥ 3.5 mm, four (11.8%) had pathogenic CNV, one (2.9%) had non-reported pathogenic CNV, one (2.9%) had pathogenic autosomal recessive variant and four (11.8%) had VUS. Four in 162 (2.5%) fetuses had CNVs at the chromosome 16p13.11 region. Amongst 154 fetuses without structural abnormalities and normal QF-PCR, three (1.9%) had a pathogenic CNV, 5 (3.2%) had non-reported pathogenic CNV, one (0.6%) autosomal recessive pathogenic CNV and 16 (10.4%) had VUS. CONCLUSION: Pathogenic CNVs were found in 1% of fetuses with an NT thickness between the 95th percentile and 3.5 mm and in 12% of fetuses with NT ≥ 3.5 mm. CNVs were found at the 16p13.11 region in 2.5% of cases.

The Overlooked Impact of Lower Uterine Segment Contractions on Second Trimester Cervical Assessment.

INTRODUCTION: Asymptomatic contractions in the lower uterine segment (LUS) may affect uterocervical angle and cervical length (CL); however, this has never been investigated. Therefore, the aim of this study was to evaluate the effect of LUS contractions on uterocervical angle, CL, and LUS thickness. MATERIALS AND METHODS: This was a prospective, observational, single-cohort study conducted on 102 asymptomatic singleton pregnancies between 19.0 and 22.6 weeks of gestation. Uterocervical angle and CL were measured by transvaginal ultrasound at two different time points with an interval of at least 20 min. LUS thickness was also measured as an indirect marker of myometrial contraction. A linear and curvilinear regression were performed to explore a potential association between LUS contractions, measured as increments in LUS thickness, and changes in CL and uterocervical angle. RESULTS: The linear regression between changes in LUS thickness and changes in CL showed that LUS contractions impact CL; for every 1-mm increase in LUS thickness, CL increased by 0.909 mm, when the isthmus was included in the CL measurement (R2 = 0.358; ß = 0.909; p < 0.001). By contrast, when the isthmus was not included in the measurement, a curvilinear relation between changes in LUS thickness and changes in CL was found (R2 = 0.077; ß1 = 0.575, ß2 = 0.038; p = 0.018). The relation between changes in uterocervical angle and changes in LUS thickness was not significant. DISCUSSION/CONCLUSION: LUS contractions can be observed in many asymptomatic women during the second trimester of pregnancy. LUS contractions lead to an increase in CL and LUS thickness, thus impacting ultrasound cervical assessments. These contractions do not affect the uterocervical angle.

Prospective evaluation of the uterocervical angle as a predictor of spontaneous preterm birth.

INTRODUCTION: The uterocervical angle has been proposed as an ultrasound marker to predict spontaneous preterm birth; however, the studies that provided this evidence were retrospective and their results heterogeneous. This study aimed to assess the ability of the uterocervical angle to predict spontaneous preterm birth before 34 and 37 weeks of gestation. MATERIAL AND METHODS: A prospective cohort study with singleton pregnancies between 19.0 and 22.6 weeks of gestation. Uterocervical angle and cervical length were measured by transvaginal ultrasound. Maternal history and pregnancy data were recorded. Delivery data were subsequently collected. RESULTS: The final analysis included 1453 singleton pregnancies. Spontaneous preterm birth before 37 weeks occurred in 52 cases (3.6%) and before 34 weeks in 17 (1.2%). For the prediction of spontaneous preterm birth before 34 weeks, the area under the curve for the uterocervical angle was 0.67 (95% CI 0.54-0.79) and the detection rates were 5.9% and 23.5% for fixed false-positive rates of 5% and 10%, respectively. For the prediction of spontaneous preterm birth before 37 weeks, the area under the curve was 0.58 (95% CI 0.50-0.67) and the detection rates were 5.8% and 18% for fixed false-positive rates of 5% and 10%, respectively. Combined predictive models were studied. To predict spontaneous preterm birth before 34 weeks, the best model was provided by a combination of uterocervical angle and cervical length (area under the curve 0.72; 95% CI 0.58-0.86). The detection rates of this model were 35.3% and 41.2% for fixed false-positive rates of 5% and 10%, respectively. To predict spontaneous preterm birth before 37 weeks of gestation, the best model was provided by a combination of uterocervical angle, cervical length, and previous history of spontaneous preterm birth (area under the curve 0.64; 95% CI 0.55-0.72). The detection rates of this model were 15.4% and 30.8% for fixed false-positive rates of 5% and 10%, respectively. Obese women and those with a history of cesarean section had a wider uterocervical angle. CONCLUSIONS: The uterocervical angle, measured mid-trimester, is a poor predictor of spontaneous preterm birth.

Intraobserver and interobserver variability in first-trimester transvaginal ultrasound cervical length.

Objectives: To determine intraobserver and interobserver variability in the measurement of different cervical length (CL) components at the first trimester (endocervical canal and isthmus), describe the optimum measurement method (single line or two lines) and establish a normality curve of first trimester CL in our population.Methods: Women who attended the first-trimester US scan, between 11.0 and 13.6 weeks of gestation at Vall d'Hebron Universitary Hospital, Barcelona, Spain were included. Inclusion criteria were singleton pregnancies in women over 18 years of age, no gestational complications, uterine malformations or uterine surgery. Lengths of the endocervical canal and uterine isthmus were measured using two methods.Results: Both methods for endocervical canal measurement, single line and two lines, showed low intraobserver variability between examiners, with no statistical differences in the majority of measurements. A correct correlation existed between examiners using the single-line two-line measurements, with a concordance correlation coefficient of 0.76.Conclusions: Cervical length in the first trimester was reproducible for the same physician and between different physicians; however, it is essential to ensure examiners receive adequate training in the technique.

Clinical application of a contingent screening strategy for trisomies with cell-free DNA: a pilot study.

BACKGROUND: Different strategies have been designed for clinical implementation of cell-free DNA (cfDNA) testing. We aimed to evaluate the performance of a contingent strategy based on conventional screening and offering cfDNA to the intermediate-risk group, for the screening for trisomies 21, 18 and 13. Secondary objectives were to assess the uptake of cfDNA in women with intermediate-risk, to evaluate the performance of cfDNA testing, and the preferences of pregnant women with intermediate risk. METHODS: Prospective observational pilot study between February 2016 and March 2017. Singleton pregnancies with a known outcome were included in the study. At the conventional screening (first trimester combined test or second trimester quadruple test) women were classified in high (risk ≥1:250) or low risk (< 1:250). For the study, a contingent strategy was applied: following the conventional screening women were classified into three groups: high risk (risk ≥1:10 or nuchal translucency ≥3 mm), intermediate-risk (risk 1:11 to 1:1500) and low risk (< 1:1500), and a cfDNA test was offered to those at the intermediate risk. RESULTS: For the analysis, 2639 women were included, 2422 (91.8%) had a first trimester combined test and 217 (8.2%) a second trimester quadruple test. There were 5 cases of trisomy 21, 4 of trisomy 18 and none of trisomy 13. For the contingent strategy, the detection rate and false positive rates were 88.9% (8/9) and 1.3% (35/2630), respectively. For the conventional strategy, the detection rate and false positive rates were 66.7% (6/9) and 5.3% (140/2630), respectively. The cfDNA test had a detection rate for trisomy 21 of 100% (3 out of 3), and a false positive rate of 0.2% (1/466). In a survey, 81.8% (374/457) of women in the intermediate-risk group would choose cfDNA testing as the second line test, mainly due to the lack of risk for the fetus. CONCLUSION: A contingent screening strategy for trisomies 21, 18 and 13, based on conventional screening, and offering a cfDNA test to women with a risk between 1:11 to 1:1500, reduced the false positive rate and increased the detection rate for these trisomies. Moreover, this strategy is well accepted by women.

Maternal history and uterine artery Doppler in the assessment of risk for development of early- and late-onset preeclampsia and intrauterine growth restriction.

Objective. To examine the value of one-step uterine artery Doppler at 20 weeks of gestation in the prediction pre-eclampsia (PE) and/or intrauterine growth restriction (IUGR). Methods. A prospective multicentre study that included all women with singleton pregnancies at 19-22 weeks of gestation (w). The mean pulsatility index (mPI) of both uterine arteries was calculated. Receiver-operating characteristics curves (ROC) were drawn to compare uterine artery Doppler and maternal risk factors for the prediction of early-onset PE and/or IUGR (before 32 w) and late-onset PE and/or IUGR. Results. 6,586 women were included in the study. Complete outcome data was recorded for 6,035 of these women (91.6%). PE developed in 75 (1.2%) and IUGR in 69 (1.1%) cases. Uterine Doppler mPI was 0.99 and the 90th centile was 1.40. For 10% false-positive rate, uterine Doppler mPI identified 70.6% of pregnancies that subsequently developed early-onset PE and 73.3% of pregnancies that developed early-onset IUGR. The test had a lower detection rate for the late-onset forms of the disease (23.5% for PE and 30% for IUGR). Maternal history has a low sensitivity in the detection of early-onset cases, although it is better at detecting late-onset PE. Conclusion. Uterine artery Doppler and maternal risk factors seem to select two different populations - early and late-onset PE which might suggest a different pathogenesis.

Composición de gases de escape de automóviles

El presente trabajo se ha establecido la metodología de muestreo y análisis de los gases de combustión del motor del vehículo y se realizó el estudio de los principales contaminantes presentes en los gases de escape de automóviles y se estimo el impacto sobre la callidad de aire en la ciudad de La Paz. Se determinarón los siguientes gases de escape CO2, CO, HC(no quemados) y O2; parámetros normados en el Reglamento de Medio Ambiente. Los resultados obtenidos comparando los promedios de emisión, antes de un afinado de motor (carburador e inyección) el vehículo emite gases que no están dentro de los límites propuestos, despues de un mantenimiento de motor los gases emitidos por los vehículos (carburador e inyección) están aceptados dentro de los límites permisibles concluyendo que un mantenimiento periódico de su vehículo no emitirá gases dañinos que aportan a la contaminación atmosférica de la ciudad..."