The value of real-time shear wave elastography in spontaneous preterm birth.

This study aimed to investigate the predictive value of real-time shear wave elastography (SWE) for spontaneous preterm birth (SPB). This study prospectively selected 175 women with singleton pregnancies at 16 to 36 weeks of gestation. Cervical length (CL) and uterocervical angle (UCA) were measured using transvaginal ultrasonography. Real-time shear wave elastography was used to measure Young's modulus values, including the average Young's modulus (Emean) and the maximum Young's modulus (Emax) at 4 points: point A on the inner lip of the cervical os, point B on the outer lip of the cervical os, point C on the inner lip of the external os, and point D on the outer lip of the external os. Receiver operating characteristic (ROC) curve analysis was performed to compare the accuracy of Young's modulus values at the 4 points, CL, and UCA in predicting SPB. Significant variables were used to construct a binary logistic regression model to predict the multifactorial predictive value of SPB, which was evaluated using an ROC curve. A total 176 valid cases, including 160 full-term pregnancies and 16 SPB, were included in this study. Receiver operating characteristic curve analysis revealed that Emean at point A, as well as Emean and Emax at point D, had a relatively high accuracy in diagnosing SPB, with area under the curve values of 0.704, 0.708, and 0.706, respectively followed by CL (0.670), SWE at point C (Emean 0.615, Emax 0.565), SWE at point B (Emean 0.577, Emax 0.584), and UCA (0.476). Binary logistic regression analysis showed that comorbidities during pregnancy (including diabetes mellitus, hypertension, cholestasis and thyroid dysfunction), CL, and Emean at point A were independent predictors of preterm birth. In addition, the AUC value of the logistic regression model's ROC curve was 0.892 (95% CI: 0.804-0.981), with a sensitivity of 0.867, specificity of 0.792, and Youden's index of 0.659, indicating that the regression model has good predictive ability for SPB. Real-time shear wave elastography showed a higher predictive value for SPB than CL and UCA. The SWE combined with CL and comorbidities during pregnancy model has a good predictive ability for SPB.

TVS-guided cervical strain elastography is more effective than measuring cervical length as an independent predictor of spontaneous preterm delivery in asymptomatic, high-risk women during the mid-trimester.

INTRODUCTION: TVS (Transvaginal Sonography) guided Cervical strain elastography (CSE) is now available in tertiary referral centers of LMICs (Low- and Middle-Income Countries). TVS cervical length (CL) assessment is being used routinely. Still, elastography is not used in clinical settings, although enough evidence suggests good predictive value towards sPTD (spontaneous Preterm Delivery). The clinical utility of elastography has not been tested among high-risk populations of LMICs for the prediction of sPTD. AIM: To test the performance of TVS-CSE in predicting sPTD among asymptomatic women in the mid-trimester at risk of sPTD either due to clinical factors or due to a short cervix. METHOD: Prospective observational study performed at a tertiary hospital in South India. Asymptomatic pregnant women between 16 and 24 weeks who had one or more clinical risk factors for sPTD or CL <2.5 cm were included. GE Voluson E-8 ultrasound machine was used. After CL measurement, elastography color coding was noted around the internal-os in the sagittal view. The strain ratio (SR) was calculated using the trace method on three ROIs (Region of Interest): Internal-os in sagittal view (IN), whole cervix in sagittal view (WN), and internal-os in axial view (AN). Reference Tissue (RT) of similar size and depth was chosen in the darkest blue region on elastography (stiffest area) outside the cervix, posterior/lateral to the cervix over the ligament insertion. Lower the SR - softer the cervix. Two trained fetal medicine consultants performed the initial 57 cases until intra/inter-observer correlation was satisfactory. Delivery before 37 weeks (after 26 weeks), in which the process of labor has begun spontaneously, or labor was induced after PPROM-was considered as sPTD. SRs were assessed to determine how well they could predict sPTD independently or combined with cervical length. RESULTS: Out of 221 recruited,17 were lost to follow-up after 32 weeks; 204 were delivered in our hospital. Irrespective of the route of delivery, 71 (34.8%) had sPTD. Of the remaining 133, 106 delivered at term, and 27 underwent medically indicated PTD. Apart from multiple pregnancies, no other preterm-related risk factors (including CL < 2.5 cm) showed significant association with sPTD. Red CSE pattern around internal-os was associated with a significantly higher (54.5%) incidence of sPTD. CLs were similar (3.63 ± 0.67 vs. 3.63 ± 0.80, p = .981) whereas SRs in all three ROIs were significantly lower among sPTD group versus no sPTD group (IN:0.65 ± 0.29 vs 0.79 ± 0.30 p = .001, WN:0.34 ± 0.13 vs 0.39 ± 0.15, p = .013, AN:0.37 ± 0.16 vs 0.48 ± 0.26, p = .002, respectively). Using ROC curves, while CL was not predictive (AUROC 0.49, p = .81), SRs showed moderate predictive value toward sPTD with the best AUC of 0.624 (p = .003) at IN. Prediction was slightly better for early sPTD <32 weeks (AUC 0.653 p = 0.03). The best cutoff for SR at IN was 0.72, below which there was a moderate accuracy in predicting sPTD (sensitivity 52.11%, specificity 60.9%, PPV 41.57%, NPV 70.44%, diagnostic OR 1.69 and overall accuracy of 57.84%). A weak positive correlation is seen between IN and CL (Pearson's correlation R = 0.181). Multi-variable binary logistic regression analysis suggested that SRs at IN (Adjusted OR - 0.259 CI 0.079-0.850), AN (Adjusted OR 0.182 CI 0.034-0.963), Multiple Pregnancy (Adjusted OR 3.5 CI 1.51-8.13) and previous sPTD/PPROM (Adjusted OR 2.72 CI 0.97-7.61) independently predicted sPTD. CONCLUSIONS: TVS CSE performed better than CL as an independent predictive tool toward sPTD, although predictive efficacy was modest at best. Since technology is now available in high-end USG machines in tertiary care centers, we propose optimal utilization of CSE in LMICs to triage at-risk populations since low SRs are strongly associated with sPTD.

Assessing the multifaceted cervix: examining cervical gland area at cervical length screening to predict spontaneous preterm birth.

BACKGROUND: Biologically active cervical glands provide a mucous barrier while influencing the composition and biomechanical strength of the cervical extracellular matrix. Cervical remodeling during ripening may be reflected as loss of the sonographic cervical gland area. As sonographic cervical length remains suboptimal for universal screening, adjunctive evaluation of other facets of the mid-trimester cervix may impart additional screening benefit. OBJECTIVE: To sonographically assess the cervical gland area at universal cervical length screening for preterm birth. STUDY DESIGN: We performed a retrospective cohort study of singletons with transvaginal cervical length screening universally performed during anatomic survey between 18 0/7 and 23 6/7 weeks and subsequent live delivery at a single institution in 2018. Uterine anomalies, cerclage, suboptimal imaging, or medically indicated preterm birth were excluded. Ultrasound images were assessed for cervical length and cervical gland area (with quantitative measurements when present). The primary outcome was spontaneous preterm birth <37 weeks. Absent and present gland groups were compared using χ2, Fisher's exact, T-test, and multivariate logistic regression (adjusting for parity and progesterone use, as well as the gestational age, cervical length, and gland absence at screening ultrasound). Gland measurements were evaluated using the Mann-Whitney-U Test and Spearman's correlation. RESULTS: Among the cohort of 772 patients, absent and present CGA groups were overall similar. Patients were on average 33 years old, ∼20 weeks gestation at screening ultrasound, and overall, 2.5% had history of prior spontaneous preterm birth. The absent gland group was more likely to have been taking progesterone (17% vs 4%, P=.04). Overall rate of preterm birth was 2.6%. However, the 2.3% of patients with absent cervical gland area were significantly more likely to deliver <37 weeks (aOR 23.9, 95% CI 6.4-89, P<.001). Multivariate logistic regression demonstrated better performance of a cervical length screening model for preterm birth prediction with the addition of qualitative gland evaluation (P<.001). Qualitative gland assessment was reproducible (PABAK 0.89), but quantitative gland measurements did not correlate with preterm birth. CONCLUSION: Qualitative gland absence at mid-gestation cervical length screening was associated with subsequent spontaneous preterm birth, whereas quantitative gland measurements were not. Multifaceted ultrasound screening may be needed to adequately evaluate the multiple biologic functions of the cervix.

Universal cervical length screening and risk of spontaneous preterm birth: a systematic review and meta-analysis.

OBJECTIVE: To evaluate the risk of spontaneous preterm birth with or without universal transvaginal ultrasound cervical length screening at the time of midtrimester scan. DATA SOURCES: Medline, Embase, ClinicalTrials.gov, and Web of Science were systematically searched from the inception of the databases to November 12, 2023, using combinations of the relevant medical subject heading terms, key words, and word variants that were considered suitable for the topic. STUDY ELIGIBILITY CRITERIA: Studies including individuals with singleton gestations at 16-25 weeks of gestation screened or not screened with universal transvaginal ultrasound cervical length screening were considered eligible. Primary outcome was spontaneous preterm birth <37 weeks; secondary outcomes were spontaneous preterm birth <34 and <32 weeks. METHODS: Random effect head-to-head analyses were used to directly compare each outcome, expressing the results as summary odds ratio and relative 95% confidence interval. The quality of the included studies was independently assessed by 2 reviewers, using the Newcastle-Ottawa scale for cohort studies and the Cochrane risk-of-bias tool for randomized controlled studies. The study was registered on the prospective register of systematic reviews database (PROSPERO) (registration number: CRD42022385325). RESULTS: Eight studies, including 447,864 pregnancies, were included in the meta-analysis (213,064 screened with transvaginal ultrasound cervical length and 234,800 unscreened). In the overall analysis, universal transvaginal ultrasound cervical length did not significantly decrease the spontaneous preterm birth rates <37 weeks (odds ratio, 0.92 [95% confidence interval, 0.84-1.01], P=.07) and <34 weeks (odds ratio, 0.87 [95% confidence interval, 0.73-1.04], P=.12), but was significantly associated with a lower risk of spontaneous preterm birth <32 weeks (odds ratio, 0.84 [95% confidence interval, 0.76-0.94], P=.002). Individuals without a prior spontaneous preterm birth had a significantly lower risk of spontaneous preterm birth <37 weeks (odds ratio, 0.88 [95% confidence interval, 0.79-0.97], P=.01) and a lower trend of spontaneous preterm birth <32 weeks (odds ratio, 0.82 [95% confidence interval, 0.66-1.01], P=.06) when screened with transvaginal ultrasound cervical length, compared with no screening. CONCLUSION: Universal transvaginal ultrasound cervical length screening usually <24 weeks in singletons without a prior spontaneous preterm birth, is associated with a significant reduction in spontaneous preterm birth <37 weeks, compared with no screening.

Longitudinal evaluation of cervical length and shear wave elastography in women with spontaneous preterm birth.

OBJECTIVE: To evaluate longitudinal changes in cervical length (CL) and mean cervical shear wave elastography (CSWE) score in women with a singleton or twin pregnancy who undergo spontaneous preterm birth (sPTB) compared with those who deliver at term. METHODS: This was a prospective longitudinal study of unselected women with a singleton or twin pregnancy attending a dedicated research clinic for screening for sPTB at four timepoints during pregnancy: 11 + 0 to 15 + 6 weeks, 16 + 0 to 20 + 6 weeks, 21 + 0 to 24 + 6 weeks and 28 + 0 to 32 + 6 weeks. At each visit, a transvaginal ultrasound scan was conducted to measure the CL and the CSWE scores in six regions of interest (ROI) (inner, middle and external parts of anterior and posterior cervical lips). The mean CSWE score from the six ROIs was calculated for analysis. Log10 transformation was applied to data to produce a Gaussian distribution prior to statistical analysis. A multilevel mixed-effects analysis was performed to compare longitudinally CL and CSWE between the sPTB and term-delivery groups. RESULTS: The final cohort consisted of 1264 women, including 1143 singleton pregnancies, of which 57 (5.0%) were complicated by sPTB, and 121 twin pregnancies, of which 33 (27.3%) were complicated by sPTB. Compared to those who delivered at term, women with sPTB had a lower CL across gestation when controlling for history of cervical surgery, number of fetuses, gestational age (GA) at cervical assessment and the interaction between GA at cervical assessment and sPTB (P < 0.001). Specifically, CL in the sPTB group was significantly lower at 21 + 0 to 24 + 6 weeks (P = 0.039) and 28 + 0 to 32 + 6 weeks (P < 0.001). Twin pregnancies had significantly greater CL throughout pregnancy compared with singleton pregnancies (regression coefficient, 0.01864; P < 0.001). After adjusting for maternal age, weight, height, body mass index and GA at cervical assessment, CSWE score in the sPTB group was significantly lower compared with that in the term-delivery group across gestation (P = 0.013). However, on analysis of individual visits, CSWE score in the sPTB group was significantly lower than that in the term-delivery group only at 11 + 0 to 15 + 6 weeks (P = 0.036). There was no difference in CSWE score between singleton and twin pregnancies throughout gestation (regression coefficient, -0.00128; P = 0.937). CONCLUSIONS: Women with sPTB have a shorter and softer cervix across gestation compared with those who deliver at term. A shorter cervix in the sPTB group is observed from the late second trimester onwards, while lower cervical stiffness in the sPTB group is observed primarily in the first trimester. CL is significantly lower in singleton pregnancies compared with twin pregnancies, while cervical stiffness does not differ between the two. Our findings indicate that the cervix tends to undergo a softening process prior to shortening in sPTB cases. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

The uterocervical angle-cervical length ratio: A promising predictor of preterm birth?

OBJECTIVE: To predict spontaneous preterm birth (sPTB) (labor before 37 weeks of pregnancy) in low-risk singleton pregnancies during the second trimester, using ultrasound markers: uterocervical angle (UCA) and cervical length (CL). METHODS: In a prospective observational cohort study, we followed primigravid women with singleton pregnancies without known risk factors for sPTB from 16+0-23+6 weeks of pregnancy until birth. Transvaginal ultrasonography on admission revealed the UCA and CL, and maternal history was obtained from submitted patient profiles. Logistic regression models disclosed significant predictive variables, and receiver operating curves (ROCs) demonstrated optimal cut-offs and test accuracy indices. Predictive functions of variables were compared using positive and negative likelihood ratios. RESULTS: In a sample of 357 participants, 41 (11.5%) experienced sPTB. UCA and CL were significantly associated with sPTB when adjusting for other variables (adjusted odds ratio: UCA 1.05, 95% confidence interval [CI] 1.02-1.07 and CL 0.82, 95% CI 0.75-0.90). Optimal cut-offs were estimated to be 106° and 33 mm for UCA and CL, respectively. We devised the novel index UCA/CL with an area under the ROC of 0.781 (95% CI 0.734-0.823), cut-off = 3.09°/mm, and improved likelihood ratios (positive: 3.18, 2.47, and 4.22; negative: 0.63, 0.52, and 0.51 for UCA, CL, and UCA/CL, respectively). CONCLUSION: The second-trimester UCA/CL was found to be a promising index to predict sPTB in low-risk singleton pregnancies. Further multicenter studies may generalize this conclusion to other gestational ages or risk groups and make it more comprehensive by considering other risk factors.

First-trimester and early-second-trimester transvaginal cervical length before 16 weeks among women with preterm and term birth: a systematic review and meta-analysis.

OBJECTIVE: This study aimed to evaluate the differences in first-trimester and early-second-trimester transvaginal cervical length between patients with spontaneous preterm birth and those with term birth. DATA SOURCES: PubMed, MEDLINE, Embase, and the Cochrane Library were systematically searched through August 2023. STUDY ELIGIBILITY CRITERIA: Studies had to include (1) transvaginal cervical length measurement before 16+0 weeks of gestation and (2) transvaginal cervical length measurement in a population of patients who delivered preterm and at term. Abstracts, studies with duplicated data, and those with cervical length measured by transabdominal ultrasound scan were excluded. METHODS: K.W.C. and J.L. searched for, screened, and reviewed the articles independently. The quality of the studies was assessed using the Newcastle-Ottawa scale. Mean differences were calculated using a random-effects model and pooled through a meta-analysis. RESULTS: A total of 5727 published articles were identified. Only 10 studies (which analyzed 22,151 pregnancies) met the inclusion criteria. All studies excluded iatrogenic preterm birth. Transvaginal cervical length was significantly shorter in women with spontaneous preterm birth than in those who delivered at term (mean difference, -0.97; 95% confidence interval, -1.65 to -0.29; P=.005; I2=69%). When a linear technique was used to measure transvaginal cervical length, a significantly shorter transvaginal cervical length was associated with spontaneous preterm birth as opposed to term birth (mean difference, -1.09; 95% confidence interval, -1.96 to -0.21; P=.02; I2=77%). A shorter transvaginal cervical length measured by other techniques was also associated with spontaneous preterm birth before 34 to 35 weeks (mean difference, -1.87; 95% confidence interval, -3.04 to -0.70; P=.002; I2=0%). When studies where interventions were given for a "short" cervix or studies with a mean transvaginal cervical length ≥40 mm were excluded, a significantly shorter transvaginal cervical length was observed among those with spontaneous preterm birth (mean difference, -1.13; 95% confidence interval, -1.89 to -0.37; P=.004; mean difference, -0.86; 95% confidence interval, -1.67 to -0.04; P=.04; respectively). The optimal transvaginal cervical length cutoff was 38 to 39 mm, yielding pooled sensitivity of 0.80, specificity of 0.45, positive likelihood ratio of 1.16, negative likelihood ratio of 0.33, diagnostic odds ratio of 5.12, and an area under the curve of 0.75. CONCLUSION: Women with spontaneous preterm birth had significantly shorter transvaginal cervical length before 16 weeks of gestation compared with those who delivered at term. The linear method and the 2-line method are acceptable techniques for measuring transvaginal cervical length.

Prediction of spontaneous preterm birth in women with previous full dilatation cesarean delivery.

BACKGROUND: A previous term (≥37 weeks' gestation), full-dilatation cesarean delivery is associated with an increased risk for a subsequent spontaneous preterm birth. The mechanism is unknown. We hypothesized that the cesarean delivery scar characteristics and scar position relative to the internal cervical os may compromise cervical function, thereby leading to shortening of the cervical length and spontaneous preterm birth. OBJECTIVE: This study aimed to determine the relationship of cesarean delivery scar characteristics and position, assessed by transvaginal ultrasound, in pregnant women with previous full-dilatation cesarean delivery with the risk of shortening cervical length and spontaneous preterm birth. STUDY DESIGN: This was a single-center, prospective cohort study of singleton pregnant women (14 to 24 weeks' gestation) with a previous term full-dilatation cesarean delivery who attended a high-risk preterm birth surveillance clinic (2017-2021). Women underwent transvaginal ultrasound assessment of cervical length, cesarean delivery scar distance relative to the internal cervical os, and scar niche parameters using a reproducible transvaginal ultrasound technique. Spontaneous preterm birth prophylactic interventions (vaginal cervical cerclage or vaginal progesterone) were offered for short cervical length (≤25 mm) and to women with a history of spontaneous preterm birth or late miscarriage after full-dilatation cesarean delivery. The primary outcome was spontaneous preterm birth; secondary outcomes included short cervical length and a need for prophylactic interventions. A multivariable logistic regression analysis was used to develop multiparameter models that combined cesarean delivery scar parameters, cervical length, history of full-dilatation cesarean delivery, and maternal characteristics. The predictive performance of models was examined using the area under the receiver operating characteristics curve and the detection rate at various fixed false positive rates. The optimal cutoff for cesarean delivery scar distance to best predict a short cervical length and spontaneous preterm birth was analyzed. RESULTS: Cesarean delivery scars were visualized in 90.5% (220/243) of the included women. The spontaneous preterm birth rate was 4.1% (10/243), and 12.8% (31/243) of women developed a short cervical length. A history- (n=4) or ultrasound-indicated (n=19) cervical cerclage was performed in 23 of 243 (9.5%) women; among those, 2 (8.7%) spontaneously delivered prematurely. A multiparameter model based on absolute scar distance from the internal os best predicted spontaneous preterm birth (area under the receiver operating characteristics curve, 0.73; 95% confidence interval, 0.57-0.89; detection rate of 60% for a fixed 25% false positive rate). Models based on the relative anatomic position of the cesarean delivery scar to the internal os and the cesarean delivery scar position with niche parameters (length, depth, and width) best predicted the development of a short cervical length (area under the receiver operating characteristics curve, 0.79 [95% confidence interval, 0.71-0.87]; and 0.81 [95% confidence interval, 0.73-0.89], respectively; detection rate of 73% at a fixed 25% false positive rate). Spontaneous preterm birth was significantly more likely when the cesarean delivery scar was <5.0 mm above or below the internal os (adjusted odds ratio, 6.87; 95% confidence interval, 1.34-58; P =.035). CONCLUSION: In pregnancies following a full-dilatation cesarean delivery, cesarean delivery scar characteristics and distance from the internal os identified women who were at risk for spontaneous preterm birth and developing short cervical length. Overall, the spontaneous preterm birth rate was low, but it was significantly increased among women with a scar located <5.0 mm above or below the internal cervical os. Shortening of cervical length was strongly associated with a low scar position. Our novel findings indicate that a low cesarean delivery scar can compromise the functional integrity of the internal cervical os, leading to cervical shortening and/or spontaneous preterm birth. Assessment of the cesarean delivery scar characteristics and position seem to have use in preterm birth clinical surveillance among women with a previous, full-dilatation cesarean delivery and could better identify women who would benefit from prophylactic interventions.

Reliability of the sonographic evaluation for cervical length and elastography with pelvic parameters in term pregnancy by experienced operators with varying levels of experience.

OBJECTIVE: To assess the reliability of sonographic measurements of six cervical and pelvic parameters by three sonographers with varying levels of experience. METHODS: A cross-sectional study was conducted in pregnant women with a gestational age of ≥39 weeks. Each pregnant woman was examined by two sonographers with different levels of experience. Six parameters were measured: cervical length (CL), cervical strain elastography (extrinsic type), posterior cervical angle (PCA), fetal head-to-perineum distance (FHPD), fetal head-to-pubic symphysis distance (FHSD), and angle of progression (AOP). Intra- and interobserver reliabilities were assessed using the intraclass correlation coefficient with a 95% confidence interval. Pearson pairwise correlation coefficients were used to analyze the correlation between the parameter values. RESULTS: In all, 66 pregnant women were enrolled in this study. We found excellent intraobserver reliability for measurements of CL, PCA, FHPD, FHSD, and AOP and good-to-excellent intraobserver reliability for cervical strain values in the cross-sectional view of the endocervix in the internal os area and cross-sectional view of the entire cervix in the internal os area. Interobserver reliability was excellent for all pelvic parameters, except for the FHPD. Strain values were moderate to excellent in the area of the internal os. A significant negative correlation between CL and strain values at the internal os was observed. CONCLUSIONS: Pelvic parameters, except for FHPD, have excellent intra- and interobserver reliabilities. The high reproducibility of CL and cervical strain elastography at the internal os level, with a negative correlation between these two parameters, may play an important role in predicting successful induction of labor.

Deep learning algorithm for predicting preterm birth in the case of threatened preterm labor admissions using transvaginal ultrasound.

PURPOSE: Preterm birth presents a major challenge in perinatal care, and predicting preterm birth remains a major challenge. If preterm birth cases can be accurately predicted during pregnancy, preventive interventions and more intensive prenatal monitoring may be possible. Deep learning has the capability to extract image parameters or features related to diseases. We constructed a deep learning model to predict preterm births using transvaginal ultrasound images. METHODS: Patients who were hospitalized for threatened preterm labor or shortened cervical length were enrolled. We used images of the cervix obtained via transvaginal ultrasound examination at admission to predict cases of preterm birth. We used convolutional neural networks (CNNs) and Vision Transformer (Vit) for the model construction. We compared the prediction performance of deep learning models with two human experts. RESULTS: A total of 59 patients were enrolled in the study, including 30 cases in the preterm group and 29 cases in the full-term group. Statistical analysis of clinical variables including cervical length showed no significant differences between the two groups. For accuracy, the best CNN model had the highest accuracy of 0.718 with an area under the curve (AUC) of 0.704, followed by Vision Transformer with accuracy of 0.645 and AUC of 0.587. The accuracy of two human experts was 0.465 and 0.517, respectively. CONCLUSIONS: Deep learning models have important implications for extraction of features that provide more accurate assessment of preterm birth than traditional visual assessment by the human eye.

Parto pré-termo espontâneo sem rotura de membranas: prevalência, fatores de risco e o papel do colo uterino / Spontaneous preterm birth without premature rupture of membranes: prevalence, risk factors and the role of the cervix

Cerca de 15 milhões de prematuros nascem por ano globalmente. Em 2015 ocorreram mais de 4 milhões de mortes de crianças menores de 5 anos, e as complicações da prematuridade são a principal causa de óbito em neonatos. O parto pré-termo é uma síndrome em que múltiplas etiologias convergem para uma via final única, e os fatores de risco mais importantes são antecedente de prematuridade e gestação gemelar. O colo uterino tem a função de manter a gestação desde a concepção até o parto, e seu processo de amadurecimento gera esvaecimento, dilatação e encurtamento, num continuum que pode compreender desde quadros de insuficiência cervical até o parto pré-termo espontâneo sem rotura de membranas. Este primeiro artigo, da série de três, descreve a prevalência da prematuridade, seus fatores de risco e o papel do colo uterino no processo de parturição.(AU)

Around 15 million preterm births happen globally. In 2015 over 4 million deaths in children under 5 years of age died and preterm birth complications is the leading cause in neonates. Preterm birth is a multiple etiology syndrome, in which various causes converge to a single parturition path. The most important risk factors are multiple gestation and obstetrical history of preterm birth. Uterine cervix is responsible for pregnancy maintenance from conception to birth, and its remodeling process generates effacement, dilation and shortening in a continuum that comprises conditions from cervical insufficiency to preterm birth without membrane disruption. This is a first article, of a series of three, describing preterm birth prevalence, risk factors and uterine cervix role in parturition.(AU)

Comprimento de colo uterino ao ultrassom transvaginal como preditor de risco do parto pré-termo espontâneo / Ultrasound cervical lenght predicting risk for spontaneous preterm birth

O encurtamento do colo uterino é parte da via final comum da parturição seja a termo ou pré-termo. A identificação precoce do comprimento cervical encurtado ao ultrassom transvaginal no segundo trimestre gestacional pode atuar como preditor de risco de prematuridade. Desde a década de 1990, vários estudiosos dedicaram-se a estabelecer parâmetros de referência para as medidas de colo uterino entre 16 e 24 semanas e até hoje o limite mais consensualmente aceito é de 25 mm. Especialistas são favoráveis à triagem universal, mas diretrizes internacionais são controversas quanto à investigação em casos sem antecedente de parto pré-termo, além de diversos estudos apresentarem que há custo-efetividade no rastreamento universal. Neste artigo, discutimos criticamente os parâmetros apresentados por estudos históricos e balizadores de conduta, a custo-efetividade e os guidelines internacionais. Propomos ainda uma reflexão ao pré-natalista, sugerindo a individualização da conduta perante os dados de cada gestante específica.(AU)

Cervical shortening is the final path of parturition, regardless if it is term or preterm. Precocious identification of a shortened cervix by transvaginal ultrasound during the second gestational trimester can act as a risk predictor of prematurity. Since the 1990´s decade, numerous studies established reference ranges for cervical length measurement between 16 to 24 gestational weeks and the most accepted cutoff limit is 25 mm. Experts indicate universal screening, however international guidelines are controversial, even in cases without a history of preterm birth, furthermore, many studies demonstrated cost-effectiveness about the universal screening of cervical length in middle gestation. In this article we discuss historical reference ranges, cost- -effectiveness, and international guidelines. We propose critical thinking and suggest individualized management according to specific characteristics of each patient.(AU)

Infecção genital e marcadores preditivos do parto prematuro / Genital infection and preterm birth predictive markers

Apesar dos avanços na área da Obstetrícia, a prematuridade ainda é a principal causa de morbidade e mortalidade neonatal. Esforços continuam sendo feitos na busca de marcadores que possam predizer tal evento e, assim, evitar o parto prematuro. A presente revisão abordou a relação da infecção genital com a prematuridade e sua influência nos resultados dos principais indicadores preditivos do parto prematuro, bem como a eficácia da antibioticoterapia. Os estudos revisados sugerem que o tratamento da vaginose bacteriana relaciona-se a resultados satisfatórios para a prevenção da prematuridade somente se realizado na primeira metade da gestação. A alteração dos testes preditivos não indica, por si só, o uso de antibióticos.

Despite advances in the field of Obstetrics, prematurity is still responsible for the leading cause of neonatal morbidity and mortality. Efforts are still being made in the search for markers that can predict such an event and thus prevent premature delivery. This review explores the relationship of genital infection with preterm birth and its influence on the results of the main preterm birth predictive markers, as well as the effectiveness of antibiotics. The revised studies suggest that treatment of bacterial vaginosis relates to satisfactory results for the prevention of preterm performed only if the first half of pregnancy. The change of predictive tests not indicates, by itself, the use of antibiotics.

Variant inferior root of ansa cervicalis / Variación de la raíz inferior del asa cervical

Ansa cervicalis is a loop of nerves found in the anterior wall of the carotid sheath in the carotid triangle of neck innervating infrahyoid muscles. Its superior root has fibres from the first cervical nerve that leaves the hypoglossal nerve and joins the inferior root formed by the branches from the second and third cervical nerves. The two roots join to form ansa cervicalis. The ansa cervicalis nerve formation is relatively complex, as its course and location along the great vessels of the neck vary. In the present case on the left side of an adult male cadaver the inferior root was absent and the contributions from C2 and C3 were joining independently with the superior root of ansa to form ansa cervicalis. However no such variation was found in the ansa cervicalis formation on the right side.

El asa cervical es un loop de nervios que se encuentra en la pared anterior de la vaina carotídea, en el triángulo carotídeo del cuello, que inerva los músculos infrahioideos. Su raíz superior tiene fibras del primer nervio cervical que sale del nervio hipogloso y se une a la raíz inferior formada por las ramas de los nervios cervicales segundo y tercero. Las dos raíces se unen para formar el asa cervical. La formación del asa cervical del nervio es relativamente compleja, ya que su curso y ubicación varía a lo largo de los grandes vasos del cuello. En el lado izquierdo del cuello de un cadáver adulto de sexo masculino, la raíz inferior del asa cervical estaba ausente y las contribuciones de los ramos de C2 y C3 se unieron, de forma independiente, con la raíz superior del asa y así formar el loop.