Transvaginal Cervical Length Research Articles

813: Sonographic cervical length for the short-term prediction of preterm birth in symptomatic patients: a meta-analysis

To assess the predictive accuracy of transvaginal sonographic cervical length measurement as a short-term predictor of preterm birth in patients with signs and symptoms of preterm labor. We searched electronic databases and syllabi from scientific meetings. We also performed manual searches of references from textbooks and of known primary and systematic review articles and contacted authors and experts in the field. We targeted cohort studies, in any language, reporting data on the diagnostic accuracy of sonographic cervical length measurement for the prediction of preterm birth within 48 hours following testing in symptomatic women. Methodological quality was assessed using the QUADAS tool and 2x2 contingency tables were constructed for data abstraction and assessment of diagnostic measures. Diagnostic meta-analysis performed using bivariate methods. Pooled estimates of sensitivity, specificity, positive and negative likelihood ratios, area under the curve, and diagnostic odds ratios (DOR) were calculated. Tests for heterogeneity, publication bias and meta-regression were also performed. Ten studies were included for analysis (2,211 subjects). QUADAS scores ranged from 8-13. For delivery within 48 hours employing 15 mm as the selected cut off, the overall pooled estimates for sensitivity and specificity were 0.77 (95% confidence interval [CI] 0.54-0.90) and 0.88 (95% CI 0.84-0.91), respectively and a DOR of 24 (95% CI 9-65). Positive and negative likelihood ratios based on the selected 15 mm cut off were 6.4 (95% CI 4.7-8.7) and 0.26 (95% CI 0.12-0.58) respectively. The area under the curve was 0.90 (0.88-0.93). Based on a pre-test probability of 10% for delivery within 48 hours of testing, post-test probabilities (positive and negative) were 42% and 3% respectively. In women with signs and symptoms of preterm labor, TVS cervical length measurement has moderate accuracy for predicting delivery within 48 hours of testing.

Étude pronostique du risque d’accouchement, des patientes hospitalisées pour menace d’accouchement prématuré, dans une maternité de niveau III

To assess preterm birth rate, in patients admitted for threatened preterm birth (TPB) in a tertiary care maternity center and evaluate our diagnostic and therapeutic tools. A retrospective cohort study, in a tertiary care maternity center (Marseille, France), reviewed all admissions for TPB from January 1 to December 31, 2009. We recorded 224 admissions for TPB (181 single pregnancies and 43 twin pregnancies), 43.8% of TPB admissions were from materno-fetal transfer. Preterm birth rate was 44.9% (n=89), 39% (n=66) for single pregnancy and 76.6% (n=23) for twins. The 15 mm threshold for transvaginal sonography cervical length (CL) was the most relevant to predict the risk of preterm delivery, 77.3% (85/110) of patients with CL>15 mm having full term delivery. For single pregnancy, most of the patients with cervical length>15 mm have full term delivery. It seems important to us to develop the use of more efficient predictive markers of risk-premature labor in order to improve the diagnosis and management of TPB.

Sonographic measurement of cervical length as a predictor of preterm delivery: a systematic review

To evaluate if transvaginal cervical length measurement in the second-trimester scan is an effective screening test for preterm delivery. We performed a search in Medline and, for each selected article, information was extracted regarding the performance of the test in terms of sensitivity, specificity, positive, and negative likelihood ratios, in low-risk, high-risk, and multiple gestations. We also evaluated the performance of the combined test (more than one sonographic marker). A positive relationship was established between short cervix and preterm delivery in all articles. The majority of studies presented high specificity and positive likelihood ratio, while sensitivity and negative likelihood ratio were variable and globally poor. Better values of accuracy were found in high-risk and multiple gestations and, in all studied subgroups, for preterm delivery at lower gestational ages. We conclude that a short cervix is predictive of preterm delivery and can identify women that may benefit from preventive and therapeutic measures, however, a negative result is not always reassuring.

Comparison of Cervical Lengths Using Transabdominal and Transvaginal Sonography in Midpregnancy

Cervical length assessment is helpful to predict and prevent preterm birth. However, transvaginal sonography is not easy to perform. The aim of this study was to investigate the relationship and discrepancies between cervical lengths measured by transabdominal and transvaginal sonography in midpregnancy. Transabdominal and transvaginal cervical lengths were measured in 255 pregnant women between 20 and 29 gestational weeks. The discrepancies in cervical lengths between the two methods were analyzed for the following maternal and fetal conditions: (1) vertex versus breech fetal presentation, (2) whether the fetal presenting part overlay the cervical internal os, (3) whether both the internal os and external os were visible or only the internal os was clearly visible, (4) maternal bladder filling status, (5) maternal age, (6) parity, and (7) gestational age. The mean cervical lengths were not significantly different (mean ± SD, 3.88 ± 0.73 cm on transabdominal sonography and 3.93 ± 0.72 cm on transvaginal sonography; P = .129; Pearson r = 0.75). The 5th-percentile transabdominal cervical length was 26.0 mm, and the transvaginal length was 27.8 mm. There were significant discrepancies between the two methods in the cases in which a fetal presenting part overlay the internal os, in the cases in which the external os was not clearly visible, and in primiparous women. Transabdominal cervical measurements were consistently shorter than transvaginal measurements in the cases with discrepancies. Transabdominal cervical length measurements are correlated with transvaginal measurements overall, and the transabdominal length is consistently shorter than the transvaginal length in cases with discrepancies. Transabdominal sonography could be used as a cervical length screening tool.

Twin and Preterm Labor: Prediction and Treatment

Twin pregnancies are increasing. Preterm birth is a major health problem with high incidence all over the world. It is known to have a higher incidence in twin pregnancies as well as being higher in IVF/ICSI pregnancies. Prediction of preterm birth in twins through transvaginal cervical length measurement and vaginal fetal fibronectin measurement are good and well-documented methods. However, this could not be applied to IVF pregnancies. Prevention of preterm birth by administration of vaginal natural progesterone or IM synthetic progesterone injections is not effective in twins. The situation was similar with administration of progesterone to IVF twin pregnancies. Prophylactic cerclage for prevention of preterm birth in twins resulted in an increase of the incidence of preterm birth. Tocolytics also are ineffective, although nifedipine may have a role in treatment of threatened preterm birth in twins.

Cost-effectiveness of transabdominal ultrasound for cervical length screening for preterm birth prevention

Transabdominal ultrasound (TAUS) cervical length (CL) screening has been proposed as an alternative to universal transvaginal screening to identify women at an increased risk of preterm birth. We sought to identify whether and under what circumstances TAUS would be cost-effective. This is a decision analytic model designed to compare an initial TAUS CL screening approach with universal transvaginal screening in a hypothetical cohort of women with a singleton pregnancy. Cost, probability, and utility estimates were derived from the existing literature. Under baseline assumptions, universal transvaginal was the dominant strategy. In comparison to TAUS, universal transvaginal CL screening reduced preterm birth by 0.03%, reduced costs by $1.2 million and increased quality-adjusted life years by 70 per 100,000 women. Although robust to many changes in many estimates, the model was sensitive to the cost of a transvaginal ultrasound, the prevalence of a short cervix and the test characteristics (ie, sensitivity and specificity) of a TAUS screening examination for short CL. Compared with an initial TAUS screen, universal transvaginal ultrasound was a more cost-effective strategy under most assumptions. Optimizing TAUS testing characteristics or applying a transabdominal screening strategy in lower risk populations may yield an initial TAUS to be cost-effective.

Value of Bishop score and ultrasound cervical length measurement in the prediction of cesarean delivery

The aim of this study was to evaluate the role of Bishop score and cervical length in predicting the outcome of induced labor. A prospective observational study was performed during a year in women undergoing labor induction. Prior to the procedure, Bishop score was evaluated by transvaginal digital examination and cervical length was measured by transvaginal ultrasound. Demographic data and labor details were recorded. A total of 197 women were analyzed; 166 women had a vaginal delivery (84.3%) and 31 had a cesarean section (15.7%). On univariate analysis, nulliparity, Bishop score >5 and cervical length <30 mm were all associated with cesarean delivery. On multivariate analysis, only nulliparity remained significantly associated with cesarean delivery and the other characteristics did not achieve statistical significance. When women were stratified according to parity, there was a significant association between cesarean delivery and nulliparity, but not multiparity. Our results suggest that Bishop score and cervical length are good predictors of successful induction of labor, particularly in nulliparous women.

Can Transabdominal Ultrasound Be Used as a Screening Test for Short Cervical Length

Objective Universal transvaginal cervical length screening can be associated with a significant logistical burden. We hypothesized that there is a threshold cervical length measured by transabdominal ultrasound above which risk for short transvaginal cervical length is extremely low. Study Design This prospective cohort study evaluated a consecutive series of women offered universal transvaginal cervical length screening during anatomy ultrasound. Transabdominal measurement of the cervix—obtained before and after voiding for each patient—was performed before transvaginal ultrasound. The study was powered to detect a transabdominal cervical length cutoff with 95% sensitivity (95% confidence interval, 90–99%) for transvaginal cervical length of ≤25 mm. Results One thousand two hundred seventeen women were included in the analysis. Prevoid transabdominal cervical length ≤36 mm detects 96% of transvaginal cervical lengths ≤25 mm with 39% specificity. A prevoid transabdominal cervical length ≤35 mm detects 100% of transvaginal cervical lengths ≤20 mm with 41% specificity. Transabdominal images of the cervix could not be obtained in 6.2% of women prevoid and 17.9% of women postvoid. Conclusion Transabdominal cervical length screening successfully identifies women at very low risk for short transvaginal cervical length. Transabdominal screening may significantly reduce the burden of universal cervical length screening by allowing approximately 40% of women to avoid transvaginal ultrasound. To ensure high sensitivity of transabdominal screening, approximately 60% of patients will still require a transvaginal study.

Can transabdominal ultrasound identify women at high risk for short cervical length?

To determine whether transabdominal cervical length screening could identify women at high risk for having a short cervix on transvaginal ultrasound. Retrospective cohort study. Tertiary referral center. A total of 703 patients with a singleton pregnancy at 18 to 23(+6) weeks of gestation who underwent transabdominal and transvaginal cervical length assessment during anatomy ultrasound at a single institution between January 2007 and October 2011. Electronic medical records were reviewed to identify women who met the study criteria. The primary outcome was the number of women with a short transabdominal cervical length (defined as ≤ 30 mm) who needed to undergo transvaginal ultrasound to detect one woman with a short transvaginal cervical length of ≤ 20 mm. In all, 703 patients were included in the primary analysis; 3.42 women with transabdominal cervical length ≤ 30 mm needed to undergo transvaginal ultrasound to detect one woman with transvaginal ultrasound cervical length ≤ 20 mm. Of women with short transvaginal cervical length ≤ 20 mm, 89.8% had a transabdominal measurement ≤ 30 mm and 96.7% had a transabdominal measurement ≤ 33 mm. Screening of transabdominal cervical length may represent a useful strategy for detecting women with short cervix on transvaginal ultrasound.

Reproductive Impact of Cervical Conization

Excisional procedures, such as loop electrosurgery (LEEP) and cold knife conization, are recommended treatments for cervical intraepithelial dysplasia (CIN). CIN and excisional treatments are associated with an increased risk of preterm delivery and premature rupture of membranes. This association is fairly consistent across studies focusing on cold knife conization, procedures removing deeper tissue specimens, and repeat procedures. Because the association is not as strong or consistent for single, shallow LEEPs, it is possible that the increased risk may be related, at least partly, to other factors (confounding). To prevent complications, treatment guidelines should be strictly followed to minimize overtreatment. General measures to prevent preterm birth, such as screening and treating infections and smoking cessation should be considered. Given the lack of evidence on the impact of progesterone to prevent preterm delivery in this population, further studies will be needed to determine if transvaginal sonographic cervical length measurement should be offered routinely during pregnancy.

Preterm Labor: Understanding of the Mechanism Involved to Improve Prediction and Prevention

Preterm birth is a significant problem occurring in around 10% of all deliveries and its increase is remarkable, even in developed countries. Being born under 37 weeks, and most importantly under 32 weeks, is the major cause of perinatal morbidity and mortality and accounts for the majority of neonatal deaths. Recent advances in perinatology and neonatology have increased survival rates, particularly for the extremely preterm baby. The associated morbidity for these survivors' remains significant, and up to one-quarter will have at least one major disability. This special issue focused in some aspect of the physiopathology of the preterm labor and different strategies to predict the patient at risk in order to improve the prevention of this pathology. This issue highlights the diversity of the physiopathology of preterm labor by including different points of view, such as focusing in the expression of steroid receptor coactivators in fetal membranes and its relationship with preterm labor. Using immunohistochemistry, western blot analysis, and real-time PCR, they demonstrate that SRC-1, SCR-2, p300, and PCAF proteins are present in nuclear extracts and display tissue-specific and labor-associated differential expression. In another paper, the authors propose a novel putative target for the prevention of infection-triggered preterm labor. They suggest that uterotonic effects of endothelin-1 (E-1) are mediated via sphingosine kinase (SphK). E-1 is a molecule that exerts potent oxytocic effects and is elevated in amniotic fluid obtained from preterm births. SphK plays a key role in ET-1-induced myometrial contractions and may represent a potential target for tocolysis to prevent preterm birth. In terms of prediction, a review accessing the accuracy of transvaginal sonographic cervical length in predicting preterm birth in women with twin pregnancy and symptoms of preterm birth is presented. The authors present a meta-analysis, using bivariate regression analysis, accounting for correlation between sensitivity and specificity. Despite the large variation in definition of preterm birth and cut-off point of cervical length and gestational age, they concluded that there is insufficient evidence to recommend the measurement of cervical length as a predictor of preterm birth in women with a twin pregnancy and symptoms of preterm birth because specificity and sensibility are low. With respect to prevention of preterm birth, a systematic review of the use of cervical pessaries and adjunctive therapies to cerclage is presented. The aim of one study was to evaluate the effective use of the cervical pessary to prevent preterm birth before 28, 34, and 37 weeks of gestation. Interestingly, one randomized controlled trial demonstrated a lower delivery rate prior to 34 weeks in the pessary group. Other studies, however, showed no positive effect. The author concluded that the cervical pessaries represent an affordable, safe, and reliable alternative for prevention of preterm birth in selected at-risk pregnant women. Nevertheless, more randomized clinical trials are needed before this device can be used in clinical practice. In another study, the authors reviewed publications that assessed the efficacy of adjunctive therapies used in addition to cervical cerclage as a preventive measure for preterm birth. The adjunctive therapies identified were progesterone, reinforcing or second cerclage placement, tocolytics, antibiotics, bedrest, and pessary. Even though small numbers of patients limited the strength of the conclusions, none of the studies clearly show the benefit of any adjunctive therapy used. By compiling these papers, we hope to improve the knowledge of clinicians and researchers with respect to this important cause of perinatal morbidity and mortality. Increasing the understanding of the physiopathology of the preterm labor and the strategies to prevent it are essential steps to avoid the consequence of this disease. S. E. Illanes J. K. Nien G. E. Rice

363: Universal transvaginal and transabdominal cervical length screening for short cervix

Universal transvaginal cervical length (TVCL) measurement has been recommended by some experts in light of recent evidence supporting interventions to reduce preterm birth in asymptomatic women with a shortened cervix. The sensitivity of transabdominal cervical length (TACL) to detect a shortened cervix remains largely unknown. The purpose of this study was to assess the ability of TACL to detect a TVCL ≤25mm.

474: Fetal fibronectin and cervical length as predictors of preterm birth in twin pregnancies, with or without 17-hydroxyprogesterone caproate

To compare the performance of cervicovaginal fetal fibronectin (FFN) and transvaginal sonographic cervical length (CL) as predictors of preterm birth (PTB) in twin pregnancies, and especially to examine whether treatment with 17-hydroxyprogesterone caproate (17Pc) diminishes the value of FFN, as suggested in a recent report (AJOG 2012;207:51).

109: The association between mid-trimester cervical length and cesarean delivery at term

109 The association between mid-trimester cervical length and cesarean delivery at term Emily Miller, William Grobman Northwestern University, Obstetrics and Gynecology, Chicago, IL OBJECTIVE: An ultrasonographically diagnosed short cervix has been associated with an increased risk of preterm birth, but the obstetric consequences of longer cervical lengths have been less well defined. The objective of this study was to determine the association between cervical length and cesarean delivery among women at term. STUDY DESIGN: This is a cohort study of women with a singleton gestation who underwent routine mid-pregnancy transvaginal cervical length assessment and delivered at term. Women who underwent planned cesarean delivery without intent to labor were excluded from analysis. Women were grouped into quartiles based on cervical length, and the association of their cervical length quartile with cesarean delivery was determined in both univariable and multivariable analysis. RESULTS: 5806 subjects were included in this analysis, of whom 58.1% were nulliparous. There were multiple differences among women in the different cervical length quartiles (Table). The frequency of cesarean delivery among the cohort was 18.9%. As cervical length increased, the chance of cesarean delivery increased as well (14.7%, 19.5%, 19.1%, and 22.4% from the 1st through 4th quartiles, respectively). After controlling for potential confounding factors, cervical length quartile remained significantly associated with an increased odds of cesarean for the second (aOR 1.49, 95% CI 1.18-1.88), third (aOR 1.47, 95% CI 1.16-1.85) and fourth (aOR 1.89, 95% CI 1.502.38) quartiles, compared to the first quartile. This relationship held true for nulliparous as well as multiparous women. CONCLUSION: Increasing mid-trimester cervical length is associated with increasing frequency of cesarean delivery in both nulliparas and multiparas. Preparatory uterine changes that enable successful labor may be initiated as early as the mid-trimester. 110 Evidence to support the safety and efficacy of vaginal delivery of twins gestation complicated by very low birthweight of second twin Eran Barzilay, Hila de Castro, Jigal Haas, Eyal Sivan, Eyal Schiff, Shali Mazaki-Tovi, Yoav Yinon Sheba Medical Center, Tel-Aviv University, Obstetrics and Gynecology, TelHashomer, Israel OBJECTIVE: To determine whether neonatal outcome is associated with the mode of delivery in very low birthweight twins. STUDY DESIGN: This was a retrospective cohort study. Inclusion criteria included: 1) twin gestation; 2) second twin birthweight of 1500 grams. Exclusion criteria included: 1) gestational age at delivery of less than 24 gestational weeks 2) fetal demise of one or both twins. A total of 206 twin gestations met the criteria and patients were classified into 2 groups according to the planned mode of delivery: 1. Cesarean delivery (n 152) and 2. Vaginal delivery (n 54). In the vaginal delivery group 24 pairs were cephalic-cephalic, 28 pairs were cephalic-non cephalic, and 2 pairs were non cephalicnon cephalic. The rates of Apgar score 7 at 5 minutes and cord blood PH 7.1 in either twin A or B were determined in the two groups. RESULTS: The mean gestational age at delivery was 31 weeks in the cesarean delivery group compared to 30 weeks of gestation in the vaginal delivery group (p 0.01). However, the mean birthweight of both twins was similar among the two groups (Twin A: 1452 grams vs. 1358 grams, p 0.18 and Twin B: 1186 grams vs. 1182 grams, p 0.9 respectively). There were no significant differences between the cesarean and vaginal delivery groups in the rates of low Apgar score (Twin A: 4.0% vs. 1.9%, p 0.5 and Twin B: 9.7% vs. 3.7%, p 0.2) and cord PH 7.1 (Twin A: 2.4% vs. 0%, p 0.3 and Twin B: 1.7% vs. 0%, p 0.4). A sub-group analysis of the vaginal delivery group revealed comparable rates of cesarean section (8.3% Vs 3.3%, p 0.4) as well as neonatal Apgar score 7 among the cephalic-cephalic and cephalicnon cephalic groups (Twin A: 4.2% vs. 0%, p 0.3 and Twin B: 0 vs. 6.7%, p 0.2). CONCLUSION: Vaginal delivery of very low birthweight twins is a safe regardless of second twin presentation. This information should provide reassurance for pregnant women and clinicians alike.

Limited Relationship between Cervico-Vaginal Fluid Cytokine Profiles and Cervical Shortening in Women at High Risk of Spontaneous Preterm Birth

ObjectiveTo determine the relationship between high vaginal pro-inflammatory cytokines and cervical shortening in women at high risk of spontaneous preterm labor and to assess the influence of cervical cerclage and vaginal progesterone on this relationship.MethodsThis prospective longitudinal observational study assessed 112 women with at least one previous preterm delivery between 16 and 34 weeks’ gestation. Transvaginal cervical length was measured and cervico-vaginal fluid sampled every two weeks until 28 weeks. If the cervix shortened (<25 mm) before 24 weeks’ gestation, women (cases) were randomly assigned to cerclage or progesterone and sampled weekly. Cytokine concentrations were measured in a subset of cervico-vaginal fluid samples (n = 477 from 78 women) by 11-plex fluid-phase immunoassay.ResultsAll 11 inflammatory cytokines investigated were detected in cervico-vaginal fluid from women at high risk of preterm birth, irrespective of later cervical shortening. At less than 24 weeks’ gestation and prior to intervention, women destined to develop a short cervix (n = 36) exhibited higher cervico-vaginal concentrations than controls (n = 42) of granulocyte-macrophage colony-stimulating factor [(GM-CSF) 16.2 fold increase, confidence interval (CI) 1.8–147; p = 0.01] and monocyte chemotactic protein-1 [(MCP-1) 4.8, CI 1.0–23.0; p = 0.05]. Other cytokines were similar between cases and controls. Progesterone treatment did not suppress cytokine concentrations. Interleukin (IL)-6, IL-8, granulocyte colony-stimulating factor (G-CSF), interferon (IFN)-γ and tumour necrosis factor (TNF)-α concentrations were higher following randomization to cerclage versus progesterone (p<0.05). Cerclage, but not progesterone treatment, was followed by a significant increase in cervical length [mean 11.4 mm, CI 5.0–17.7; p<0.001].ConclusionsAlthough GM-CSF and MCP-1 cervico-vaginal fluid concentrations were raised, the majority of cervico-vaginal cytokines did not increase in association with cervical shortening. Progesterone treatment showed no significant anti-inflammation action on cytokine concentrations. Cerclage insertion was associated with an increase in the majority of inflammatory markers and cervical length.

Can transabdominal ultrasound be used as a screening test for short cervical length?

Universal transvaginal cervical length screening can be associated with a significant logistical burden. We hypothesized that there is a threshold cervical length measured by transabdominal ultrasound above which risk for short transvaginal cervical length is extremely low. This prospective cohort study evaluated a consecutive series of women offered universal transvaginal cervical length screening during anatomy ultrasound. Transabdominal measurement of the cervix-obtained before and after voiding for each patient-was performed before transvaginal ultrasound. The study was powered to detect a transabdominal cervical length cutoff with 95% sensitivity (95% confidence interval, 90-99%) for transvaginal cervical length of ≤25 mm. One thousand two hundred seventeen women were included in the analysis. Prevoid transabdominal cervical length ≤36 mm detects 96% of transvaginal cervical lengths ≤25 mm with 39% specificity. A prevoid transabdominal cervical length ≤35 mm detects 100% of transvaginal cervical lengths ≤20 mm with 41% specificity. Transabdominal images of the cervix could not be obtained in 6.2% of women prevoid and 17.9% of women postvoid. Transabdominal cervical length screening successfully identifies women at very low risk for short transvaginal cervical length. Transabdominal screening may significantly reduce the burden of universal cervical length screening by allowing approximately 40% of women to avoid transvaginal ultrasound. To ensure high sensitivity of transabdominal screening, approximately 60% of patients will still require a transvaginal study.

Cervical length and risk of antepartum hemorrhage in presence of low-lying placenta

Objectives: To evaluate whether transvaginal ultrasound cervical length (TVU CL) can predict antepartum bleeding (APB) in women with low-lying placenta. Study design: A retrospective study was performed including pregnancies with low-lying placenta for which third trimester TVU CL was available. Multiple pregnancies were excluded. Short cervix was defined as TVU CL ≤25 mm. Outcomes of interest were compared with respect to the TVU CL. Results: Forty three cases of singleton pregnancies complicated by low-lying placenta in third trimester were identified. Short cervix was reported in 8 cases (19%). APB (75% vs. 31 %, p = 0.02), blood transfusions (25% vs. 3%, p = 0.02), lower birth weight (2246 vs. 2985 g, p = 0.02), and neonatal intensive care unit (NICU) admissions (50% vs. 17%, p = 0.04) were more frequent in the women with short cervix. Rate of unplanned cesarean delivery for APB was similar between both the groups (25% vs. 28%, p = 0.83). Conclusions: In women with low-lying placenta persisting into third trimester, short cervical length can be used as a predictor for APB.

Vaginal progesterone in risk reduction of preterm birth in women with short cervix in the midtrimester of pregnancy.

Preterm birth is a major health problem for the neonate, family, country, and society in general. Despite many risk factors being identified for women destined to deliver preterm, short cervical length detected on transvaginal ultrasound is the most plausible, practical and sensitive risk factor for prediction of spontaneous preterm birth. The definition of short cervix has varied in various studies, but most commonly accepted is ≤2.5 cm in the midtrimester of pregnancy, though risk of spontaneous preterm birth (sPTB) increases as the cervical length decreases. Vaginal progesterone, a naturally occurring steroid hormone, is the most bioavailable form of progesterone for uterine and cervical effects with the fewest side effects. Multiple prospective studies have consistently shown its benefits in decreasing sPTB rate in women with asymptomatic midtrimester short cervix. The safety for mother and fetus, and tolerability of vaginal progesterone, particularly the gel form, is also well established. Vaginal progesterone is a minimally invasive intervention that is not painful and is very safe, with reasonable cost where the benefits (even if argued to be small) clearly outweigh the risks. Thus there should be little hesitation for implementation of universal transvaginal cervical length screening and preventive vaginal progesterone treatment for women with short cervix.

Validity of Clinical and Ultrasound Variables to Predict the Risk of Cesarean Delivery After Induction of Labor

To evaluate a previously described score to predict the risk of cesarean delivery after induction of labor. We conducted a multicenter prospective study among women at 36 weeks of gestation or more undergoing induction of labor in the maternity units of Geneva, Switzerland, and Novi Sad, Serbia. Before induction, we calculated the risk score for cesarean delivery including data on maternal height, body mass index, parity, and transvaginal ultrasonographic cervical length. We calculated the sensitivity and specificity of the score using different cutoffs of calculated risk. Of the 537 women included in the analysis, 92 (17%) had a cesarean delivery. Among the variables tested, only the transvaginal ultrasonographic cervical length was associated with the risk of cesarean delivery (P<.001). Using the different cutoffs of calculated risk of cesarean delivery (20%, 30%, and 40%), we calculated the sensitivity (69.6%, 54.3%, and 45.7%, respectively), specificity (42.0%, 58.2%, and 69.2%, respectively), and positive predictive value (19.9%, 21.0%, and 23.5%, respectively) of the risk score. The area under the receiver operating characteristic curve was 0.59. There was a poor association between the outcome of labor induction (vaginal delivery or cesarean delivery) and the predicted risk. The evaluated score was not useful to predict the outcome of women undergoing labor induction. Our results show the necessity of validating existing scores in different settings and patient populations before widespread implementation in clinical care.

Universal maternal cervical length screening during the second trimester: pros and cons of a strategy to identify women at risk of spontaneous preterm delivery

Three large randomized controlled trials investigating the efficacy of universal cervical length screening and treatment with vaginal progesterone or cervical cerclage to prevent preterm delivery have been published over the past several years. None of these trials demonstrate proven efficacy for universal cervical length screening and cerclage placement in women with short cervical length. However, universal cervical length screening and treatment with daily vaginal progesterone in women with short cervical length reduces the risk of preterm birth, but large numbers of women must be screened to prevent a relatively small number of preterm deliveries. Issues that should be considered while implementing universal cervical length screening include: (1) standards of quality and reproducibility for transvaginal ultrasound cervical length ascertainment; (2) implications of screening on the application of therapeutic strategies to populations not known to benefit (so-called "indication creep"); and (3) willingness of obstetricians to prescribe vaginal progesterone formulations that are not approved by the US Food and Drug Administration for preterm birth prevention. Optimal strategies to employ cervical ultrasound and progesterone treatment might be revealed by additional studies investigating cervical length cutoffs, frequency of screening, selective screening in higher-risk groups, and the use of transabdominal cervical length screening as a surrogate for transvaginal cervical length screening.