Sonographic Measurement Of 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.

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.

Assessment of cervical length by transvaginal ultrasonography to predict preterm delivery in twin pregnancy

Objective: In singleton pregnancy, short cervix is associated with the risk of spontaneous preterm delivery (SPD). On the other hand, twin pregnancy increases rate of preterm delivery, so this study was designed to evaluate the transvaginal sonographic (TVS) measurement of cervical length (CL) to predict preterm birth in twin pregnancy.Methods: This prospective cohort study was performed on 80 twin pregnant women whom the length and funneling of their cervix were evaluated between 22–24 gestational weeks by (TVS). They referred to us at the early signs of labor. Then the gestational age at delivery was recorded. The Fisher exact test and the odds-ratio was used to determine the association between CL and SPD.Results: Thirty-four (42.5%) women had SPD. Cervical funneling happened in 7.5% of cases and SPD occurred in all women with funneling. There was a significant correlation between CL ≤ 30 mm and SPD (66.7% versus 35.5%, p = 0.029) Also, the risk of SPD was enhanced 3.6 times with CL ≤30 mm, CI 95% (1.1–11).Conclusion: We recommend TVS for assessment of CL between 22–24 weeks for prediction of SPD in twin pregnancy.

The negative predictive value of cervical interleukin-6 for the risk assessment of preterm birth

Objective: To determine the potential clinical use of cervical interleukin-6 (IL-6) as a negative predictor of preterm birth in symptomatic women.Study design: Observational prospective study carried out in a tertiary hospital.Patients and methods: We studied 100 singleton pregnant women with threatened preterm delivery and intact membranes, between 24 and 34 weeks, recruited during the period 2006–2008. A cervical swab for IL-6 detection was taken and a transvaginal ultrasound scan was performed for measuring the cervical length.Results: Five women delivered within 2 d and six women within 7 d. A high cervical IL-6 concentration was found in these women. The area under the ROC curve for cervical IL-6 was 0.97 for deliveries within 2 d after the test, and 0.85 for deliveries within 7 d. The optimal cut-off point was a cervical IL-6 concentration of 210 pg/ml. The negative predictive value (NPV) was 100% for deliveries within 2 d, and 98.5% for deliveries within 7 d (when considering a prevalence of preterm birth of 8%). Cervical IL-6 and sonographic measurement of cervical length showed similar NPV.Conclusion: A low-cervical IL-6 concentration can accurately identify symptomatic women with a very low chance to progress to preterm birth within 2–7 d.

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.

Gestational age at cervical length measurement and preterm birth in twins

To estimate the risk of preterm delivery of twin pregnancies based upon sonographic cervical length measurement and gestational age at measurement. Twin pregnancies that delivered between 1999 and 2005 and that underwent sonographic measurement of cervical length between 13 and 34 + 6 weeks' gestation were identified and a retrospective review performed. Women with anomalous pregnancies, multifetal reduction, cerclage placement or medically indicated deliveries before 35 weeks were excluded. Logistic regression analysis was used to estimate the risk of preterm delivery before 35 weeks. A total of 561 women underwent 2975 sonographic cervical length measurements during the study period. The rate of preterm delivery before 35 weeks was 19.4%. The risk of delivery before 35 weeks decreased by approximately 5% for each additional mm of cervical length (odds ratio (OR) 0.95 (95% CI, 0.93-0.97); P < 0.001) and by approximately 6% for each additional week at which the cervical length was measured (OR 0.94 (95% CI, 0.92-0.96); P < 0.001). The gestational age at which cervical length is measured is an important consideration when estimating the risk of spontaneous preterm birth in twins. The risk of preterm delivery is increased at earlier gestational ages and as cervical length decreases.

Labour induction at term: clinical, biophysical and molecular predictive factors

The aim of this multicentric study is to compare clinical, biophysical and molecular parameters in the prediction of the success of labour induction with prostaglandins. We included 115 women, who underwent to labour induction at term with vaginal prostaglandin gel. We evaluated the diagnostic efficiency of endocervical phosphorylated insulin-like growth factor-binding protein (phIGFBP-1), cervicovaginal interleukins 6 (IL-6) and 8 (IL-8). We analyzed the transvaginal sonographic measurement of cervical length. A receiver-operating characteristics (ROC) curve was used to determine the most useful cut-off point. A multivariate logistic regression model was used to analyze the combination of significant predictive variables following univariate analysis. We analyzed all the data searching for the parameters that best predict the beginning of the active phase of labour within 12 h. 36.5 % of the patients delivered within 12 h. The Bishop score was >4 in the 43 % of patients with an active phase. The best cut-off values at ROC curves for cervical length, IL-6 and IL-8 were respectively 22 mm, 5 mg/dl and 20,237 mg/dl. At univariate analysis, all predictors of success, with the exception of IL-6, were significantly associated with the beginning of the active phase. Multivariate analysis of the Bishop score (OR 2.3), phIGFBP-1 test (OR 11.2) and IL-8 (OR 6.6) showed that the variables were independent and therefore useful in combination to predict the success of labour induction. The phIGFBP-1 test is a fast and easy test that can be used with Bishop score and IL-8 to reach an high positive predictive value in the prediction of the success of labour induction with prostaglandins.

Transabdominal evaluation of uterine cervical length during pregnancy fails to identify a substantial number of women with a short cervix

Objective: To assess the diagnostic performance of transabdominal sonographic measurement of cervical length in identifying patients with a short cervix. Methods: Cervical length was measured in 220 pregnant women using transabdominal and transvaginal ultrasound (US). Reproducibility and agreement between and within both methods were assessed. The diagnostic accuracy of transabdominal US for identifying cases with a cervical length <25 mm was evaluated. Results: Twenty-one out of 220 cases (9.5%) had a cervical length <25 mm by transvaginal US. Only 43% (n = 9) of patients with a short cervix were correctly identified by transabdominal US. In patients with a cervical length of <25 mm by transvaginal US, transabdominal measurement of the cervix overestimated this parameter by an average of 8 mm (95% LOAs, −26.4 to 10.5 mm). Among women without a short cervix, transabdominal US underestimated cervical length on average (LOA) by 1.1 mm (95% LOAs, −11.0 to 13.2 mm). Transvaginal US was also more reproducible (intraclass correlation coefficient: (ICC) (0.96; 95% CI, 0.94 to 0.97) based on comparisons between 2D images and immediately acquired 3D volume datasets relative to transabdominal US (ICC: 0.71; 95% CI, 0.57 to 0.84). Transvaginal US detected 13 cases with funneling and six cases with sludge whereas only three cases of funneling and one of sludge were detected by transabdominal US. Conclusion: Transabdominal measurement overestimated cervical LOA by 8 mm among women with a short cervix and resulted in the underdiagnosis of 57% of cases.

Large loop excision of transformation zone and cervical length in the prediction of spontaneous preterm delivery

To investigate the association between previous large loop excision of transformation zone (LLETZ) and risk for subsequent spontaneous preterm delivery (sPD) and whether this effect is reflected in the measurement of cervical length at mid-gestation. A secondary analysis of data from women recruited for clinical trials of interventions to prevent preterm labour. A total of 26,867 women with singleton pregnancies attending for routine antenatal care. Transvaginal sonographic measurement of cervical length was carried out at 20(+0) to 24(+6) weeks. Logistic regression analysis was used to determine the significant predictors of sPD among maternal characteristics, obstetric history, previous history of LLETZ and cervical length. Spontaneous preterm delivery. In the 473 women who had undergone LLETZ, compared with the 25,772 without a history of LLETZ, the rate of sPD before 34 weeks of gestation was higher (3.4 versus 1.3%, P = 0.0002) and the median cervical length was shorter (32 mm versus 34 mm, P < 0.0001). Regression analysis demonstrated that in the prediction of sPD there were significant contributions from racial origin, cigarette smoking, previous preterm delivery and LLETZ and the detection rate of sPD was 29.8%, at a false-positive rate of 10%. However, after addition of cervical length, LLETZ did not remain a significant predictor in the model, which detected 52.6% of sPD, at a false-positive rate of 10%. LLETZ increases the risk of sPD, even after adjustment for maternal risk factors. The effect of a previous LLETZ on sPD in a subsequent pregnancy is reflected in the measurement of cervical length at mid-gestation.

Rate of sonographic cervical shortening and the risk of spontaneous preterm birth

We hypothesized that change in cervical length (CL) on serial ultrasounds is associated with spontaneous preterm birth (SPTB) <36 weeks for women with a short cervix (CL <25 mm). This was a secondary analysis of a multicenter prospective observational study designed to study predictors of preterm birth. Women from the general obstetric population had serial CL ultrasounds between 20-33 weeks' gestation and were followed up until delivery. Two thousand six hundred ninety five women had sonographic CL measurements. Change in CL was associated with SPTB for women with CL <25 mm (odds ratio, 0.97; 95% confidence interval, 0.96-0.98). Among women with a short cervix, for every 1 mm of cervical shortening between ultrasounds, there was a 3% increase in odds of SPTB. The association between change in CL and SPTB remained significant after controlling for age, race, body mass index, tobacco use, and fetal fibronectin test status. Among women with a sonographically short cervix, the rate of change in CL is associated with SPTB, independent of fetal fibronectin test and other important risk factors for SPTB.

P16.12: Preinduction sonographic measurement of cervical length in the prediction of successful induction of labor

P16.12: Preinduction sonographic measurement of cervical length in the prediction of successful induction of labor

Sonographic cervical length measurement in pregnant women with a cervical pessary

The aims of this study were to describe and assess the feasibility of measuring cervical length by standard transvaginal sonography (TVS) and transperineal sonography (TPS) in women with a cervical pessary and compare these measurements with those obtained with a new transvaginal technique. Measurement of cervical length by TPS was attempted immediately before measurement using TVS in 48 women with a cervical pessary at between 22 and 23 weeks' gestation. The TVS procedure consisted of two types of measurement: in the first, the probe was placed on the anterior fornix (standard technique) and in the second, the probe was inserted into the pessary to touch the anterior cervical lip (new technique). Two physicians consecutively performed these procedures and compared the measurements obtained. Intraclass correlation coefficients (ICCs) with 95% CI were used to evaluate interobserver reliability, and Bland-Altman analysis was used to assess interobserver agreement. In total, 258 measurements (obtained from 43 women) were analyzed. Interobserver ICCs of the measurements obtained were 0.58 (95% CI, 0.34-0.75) for TPS, 0.65 (95% CI, 0.44-0.79) for the standard TVS technique and 0.97 (95% CI, 0.95-0.98) for the new TVS technique. Bland-Altman analysis showed small mean differences between measurements obtained by two physicians for the three methods, but with narrower limits of agreements (LOA) for the new TVS technique: TPS mean difference - 0.99 mm (95% LOA, - 13.23 to 11.25 mm), standard TVS technique mean difference - 0.23 mm (95% LOA, - 10.90 to 10.44 mm) and new TVS technique mean difference - 0.01 mm (95% LOA, - 2.57 to 2.55 mm). It was apparent from the images obtained that the external os was not visible in 89% of cases when either the TPS or standard TVS technique was used. However, the external os was visible in all cases when the new TVS method was used. We propose a new technique for measuring and monitoring cervical length in women with a cervical pessary that provides improved visualization of the cervix and increased reliability in comparison to established techniques.

Raised electrical uterine activity and shortened cervical length could predict preterm delivery in a low-risk population

To compare diagnostic accuracy of sonographic cervical length (CL) measurement and uterine electric activity assessed by electromyography (EMG) in second trimester regarding prediction of preterm delivery (PTD). Prospective study of 308 low-risk women. Shortened CL was defined as ≤25mm (≤5th centile), while raised EMG activity was defined as the presence of ≥20 action potentials in 20min of assessment (≥95th centile). Outcome measures were diagnostic accuracy of both tests alone or in combination for prediction of PTD and early PTD (≤34weeks). The incidence of PTD was 23/308 (7.4%) while the incidence of early PTD was 9/308 (2.9%). Shortened CL and raised EMG activity were significantly related to PTD [prevalence-weighted likelihood ratio (pw-LR) 1.9, 95% CI 1.0-3.5 vs. 9.5, 95% CI 2.5-35.7], but not to early PTD (pw-LR 0.4, 95% CI 0.2-0.8 vs. 0.6, 95% CI 0.3-1.7). Significant predictive value for early PTD was found only if both tests were combined (pw-LR 4, 95% CI 1.3-14.3). Shortened CL and raised EMG activity in second trimester have significant diagnostic accuracy regarding prediction of PTD in a low-risk population. However, in order to be useful as a predictor for early PTD both tests must be positive.

Sonographic measurement of cervical length and risk of preterm delivery

To study the relationship between cervical lengths measured by ultrasound and risk of preterm delivery. We examined 209 women with singleton pregnancies. The inclusion criteria were women who presented with regular and painful contractions (≥2 contractions at intervals of 10 min for at least 1 h). Transvaginal scan was performed to measure the cervical length. The clinical management of the women, including hospitalization and administration of tocolytics, was determined by the attending obstetricians, who were blinded about cervical length. The primary outcome was delivery within 7 days of presentation. Delivery within 7 days of presentation occurred in 19/209 (9%) of pregnancies who were presenting with regular and painful uterine contraction at 31 weeks of gestation, and this was inversely related to cervical length. Logistic regression analysis demonstrated that cervical length and history of abortion remain as significant contributors to predicting delivery within 7 days. Of the patients who presented with threatened preterm labor, 117 (56%) received tocolytics, and 92 (44%) did not. In the group with a cervical length of <15 mm, delivery within 7 days occurred in 15/21 (71.4%) who were treated with tocolytics and 2/5 (40%) that were managed expectantly. Women with threatened preterm labor and a cervical length of <15 mm at presentation are at high risk of delivering preterm within 7 days. Sonographic measurement of cervical length helps to avoid over-diagnosis of preterm labor.

Effect of cervical length on second trimester pregnancy termination

To evaluate the value of sonographic measurement of cervical length as a predictor of abortion or delivery within 24 h by misoprostol in second trimester termination of pregnancy (TOP). One hundred and sixty-three women underwent TOP between 14 and 26 weeks of pregnancy due to various indications. The primary outcome was abortion within 24 h. Cervical length was measured before transvaginal administration of misoprostol. The effects of cervical length, total misoprostol dose, parity, and gestational age at diagnosis on successful TOP were evaluated. One hundred and sixty-three women were eligible who met the inclusion criteria. TOP occurred in 80.5% of patients within 24 h. Parous women had shorter prolonged induction to expulsion period over 24 h (14.1% vs 28.6%, P = 0.061). Total misoprostol dose and history of abortion were parameters that affected induction to delivery period (P = 0.002 and P = 0.041). Using an optimum cutoff of 36 mm, 58.2% sensitivity and 68.2% specificity were obtained. In addition, positive and negative predictive values were 85.36% and 33.3%, respectively. Pregnant women whose preinduction cervical length was shorter than 36 mm had a shorter induction time and needed a lower total misoprostol dose to achieve TOP than women with a cervical length longer than 36 mm (P = 0.027 and P = 0.011, respectively). Transvaginal measurement of cervical length before administration of prostaglandin analogue was not correlated with successful TOP within 24 h. It cannot be used as a predictor in light of our findings.

503: Rate of sonographic cervical shortening and the risk of spontaneous preterm birth

Sonographic measurement of cervical length (CL) identifies women at risk for spontaneous preterm birth (SPTB). Current evidence supports a relation between a short cervix at a point in time (e.g. < 25 mm) and SPTB. Among women with a short cervix, it is unknown whether subsequent sonographic shortening is related to the risk of SPTB. We hypothesized that change in CL on serial CL ultrasounds is associated SPTB <36wks for women with a short cervix (CL<25mm).

494: Scheduled timing of and patient compliance with longitudinal sonographic cervical length (CL) measurement in a multicenter randomized trial of ultrasound-indicated cerclage

To assess the timing of CL measurement and compliance with scheduled visits in women at high risk for recurrent preterm birth (PTB). Women with ≥1 prior spontaneous PTB 17-336/7 wks had an initial scan at 16-21 wks. Unless randomization occurred at the initial scan, follow-up visits were scheduled biweekly if CL ≥30 mm, increased to weekly if 25-29 mm. Women were randomized: cerclage or no-cerclage if CL<25 mm. The final scan was scheduled by 226/7 wks. Birth in the prescribed scanning window 16-226/7 wks and gestational age (GA) at birth were evaluated. Of 674 non-randomized women, only 11 (1.6%) delivered in the GA window <23 wks. The rate of birth <23 wks was 1.6% in 379 women with perfect compliance and 1.7% in 295 women who were either late for any visit or who missed their final scan (p=1.00). 183 (27.2%) did not present for their final scan < 23 wks, and these non-compliant women delivered at a mean (SD) GA of 37.0 (4.0) as compared to 37.2 (3.8) wks for those who were compliant (p=0.66). Women who missed their final 1-week follow-up (last observed CL 25-29 mm), delivered at 36.4 (4.4) wks compared to 37.1 (3.9) wks in those whose missed scan was a 2-week follow-up (last observed CL ≥30 mm; p=0.55). Of 189 women randomized after the initial scan, 91 were assigned to cerclage and 98 to no-cerclage. In the cerclage group the rates of birth <23 weeks were 4% in 78 with perfect compliance and 0 (0%) in 13 who missed ≥1 scheduled visit (p=1.00). In the no-cerclage group the rates of birth <23 weeks were 7.5% in 80 with perfect compliance and 0 (0%) in 18 who were non-compliant (p=0.59). Women at high-risk for recurrent PTB followed with serial CL measurement using a defined scanning interval based on CL, with an intent for ultrasound-indicated cerclage, have a low, 1.8% risk of birth <23 wks. The effect of non compliance with scheduled scans was null. For non-randomized women who missed their final scan, mean birth GA did not depend on whether the last observed CL was 25-29 vs. ≥30 mm.

Does cervical length and the lower placental edge thickness measurement correlates with clinical outcome in cases of complete placenta previa?

To evaluate the effectiveness of cervical length and the lower placental edge thickness measurement in predicting the risk of antepartum hemorrhage (APH) and emergency preterm cesarean delivery in women with complete placenta previa. Fifty-four cases with confirmed diagnosis of complete placenta previa in third-trimester were subjected to transvaginal sonographic measurement of cervical length and lower placental edge thickness and correlated this to clinical outcome with regards to gestational age at delivery, ante partum hemorrhage, emergency cesarean section before 36 weeks due to massive hemorrhage and neonatal birth weight. Antepartum bleeding and emergency cesarean section rate before 36 weeks due to massive bleeding were significantly higher in cases with thick lower placental edge or central placenta than cases with thin lower placental edge [16 cases (53.3%) vs. 5 cases (20.8%)] for the former and [14 cases (46.6%) vs. 4 cases (16.6%) for the later]. Antepartum bleeding was observed in 18 cases (51.4%) when cervical length measurements ≤30 mm of whom 16 cases (88.9%) had showed severe attack necessitated emergency cesarean delivery before 36 weeks versus 4 cases (21.1%) with cervical length ≥30 mm. By combining cervical length with lower placental edge thickness measurement sensitivity, specificity, positive predictive value (PPV) negative predictive value (NPV) and accuracy increased to 83.3, 78.4, 53.4, 79.8 and 89.7%, respectively for the prediction of antepartum bleeding and emergency cesarean section <36 weeks using receiver-operating characteristics curve with area under the curve 0.882. Short cervical length at cut-off value ≤30 mm and increased lower placental edge thickness measurements may predict with high accuracy the risk of APH and emergency preterm cesarean delivery in patients with complete placenta previa.

Degree of cervical shortening after initial induction of labor as a predictor of subsequent successful induction

To evaluate whether the degree of cervical length shortening is valuable in predicting the success of serial induction of labor on the second day in women in whom it failed on the first day, and to compare its performance with that of cervical length. This was a prospective observational study. We enrolled 92 consecutive women with singleton gestations at > 34.0 weeks' gestation who failed labor induction on the first day of serial induction. Transvaginal sonographic measurement of cervical length and determination of the Bishop score were undertaken before performing each labor induction on the first and second days. The overall success rate of labor induction performed on the second day was 65% (60/92). Multiple logistic regression analysis demonstrated that the degree of cervical length shortening and cervical length were significantly associated with the successful induction of labor after adjustment for body mass index, parity, use of prostaglandin and Bishop score. There were no significant differences between areas under the ROC curves for degree of cervical length shortening and cervical length. The degree of cervical length shortening is valuable in predicting the success of induction of labor on the second day in women in whom induction failed on the first day. However, compared with sonographic cervical length it is no better at predicting the success of subsequent induction of labor.

P32.07: Sonographic cervical length measurement before labor induction in VBAC

P32.07: Sonographic cervical length measurement before labor induction in VBAC