Transvaginal Cervical Length Measurement Research Articles

Prior Cerclage: To Repeat or Not to Repeat? That Is the Question

A previous study suggested that women who have had a cerclage in a prior pregnancy for nontraditional indications should avoid repeat cerclage in a subsequent pregnancy because of complications of cerclage placement that are deleterious to both the pregnancy and the health of the woman. The investigators evaluated this recommendation by accessing a database containing clinical information from pregnancies between 1995 and 2002, to identify 56 women ≥12 weeks of gestation who had a history of prior cerclage for nontraditional indications and had a subsequent pregnancy. Twenty-eight women who underwent a history-indicated cerclage (HIC) were matched by demographics and risk factors with 28 women who were managed by serial transvaginal ultrasound cervical length measurements. Spontaneous birth >35 weeks was the primary outcome. No differences were found between the 2 groups in the incidence of spontaneous preterm labor <35 weeks (21% vs. 11%; P = .5), spontaneous preterm rupture of the membranes <35 weeks (7% vs. 11%; P = 1.0), or spontaneous preterm birth <35 weeks (11% vs 11%; P = 1.0). The mean gestational age at delivery was 36.5 ± 5.6 for the prophylactic HIC group and 36.3 ± 6.6 in the transvaginal ultrasound (TVU) group (P = 0.5). The investigators concluded that, for women with history of prior cerclage for nontraditional indications, HIC did not improve outcome in the subsequent pregnancy compared with TVU CL.

Transvaginal measurement of cervical length in the prediction of successful induction of labour

SummaryA total of 100 women with gestational ages of 34–42 weeks requiring induction of labour were consecutively recruited in a prospective study at the Medical College and Hospital, Baroda, India. The aim of this study was to determine the value of transvaginal measurement of cervical length in the prediction of successful vaginal delivery within 24 h. Induction of labour was carried out with Tab Misoprostol (25 μg). A Bishop's score and sonographic cervical assessment were performed prior to induction. Univariate and logistic regression analyses was used. A pre-induction cervical length measurement on TVS was an independent predictor of successful vaginal delivery. At ≤3 cm cervical length, the probability of a LSCS was <30%, while with 4 cm cervical length, the probability became >75%. One unit increase in cervical length increased the probability of LSCS by 45%. The cervical length measurement by TVS is therefore an independent predictor of successful labour induction and performs better than Bishop's score as a method of pre-induction cervical assessment.

Transperineal versus transvaginal sonographic cervical length measurement in second‐ and third‐trimester pregnancies

To investigate the reliability of, and patient satisfaction with, transperineal cervical length measurement during the third trimester of pregnancy and to compare these with measurement during the mid-trimester, using transvaginal sonographic imaging of the cervix as a reference. Women attending an outpatient clinic for cervical length measurement before 29 weeks or after 35 weeks of gestation were examined by transvaginal and transperineal ultrasound and the results compared. Preference for either method was indicated by both sonographers and patients. Seventy-one patients participated in the study, 23 in the second and 48 in the third trimester of pregnancy. There was failure to obtain a clear image on transperineal ultrasound in 30% of mid-trimester pregnancies, and in 19% of third-trimester cases. Elevation of the patient's hips improved the image in five out of 10 women in whom the scan was repeated following a postural change. Transvaginal cervical length measurements could be obtained in all cases. There was a strong correlation between transvaginal and transperineal measured cervical length (Pearson's correlation coefficient = 0.85). Sonographers preferred transvaginal images of the cervix irrespective of whether they were obtained in the second or third trimester. Transperineal ultrasound was judged as not or mildly painful by most women, but transvaginal ultrasound was preferred. Transvaginal ultrasound is the least painful, most feasible, and probably most accurate method with which to measure cervical length in the third trimester of pregnancy. Transperineal ultrasound is a feasible alternative, although its application in clinical practice is restricted by the need for an experienced sonographer.

Centile charts of cervical length between 18 and 32 weeks of gestation

Objective To establish a centile chart of cervical length between 18 and 32 weeks of gestation in a low-risk population of women. Methods A prospective longitudinal cohort study of women with a low risk, singleton pregnancy using public healthcare facilities in Cape Town, South Africa. Transvaginal measurement of cervical length was performed between 16 and 32 weeks of gestation and used to construct centile charts. The distribution of cervical length was determined for gestational ages and was used to establish estimates of longitudinal percentiles. Centile charts were constructed for nulliparous and multiparous women together and separately. Results Centile estimation was based on data from 344 women. Percentiles showed progressive cervical shortening with increasing gestational age. Averaged over the entire follow-up period, mean cervical length was 1.5 mm shorter in nulliparous women compared with multiparous women (95% CI, 0.4–2.6). Conclusions Establishment of longitudinal reference values of cervical length in a low-risk population will contribute toward a better understanding of cervical length in women at risk for preterm labor.

Is Transabdominal Sonography of the Cervix After Voiding a Reliable Method of Cervical Length Assessment?

The purpose of this study was to assess the correlation and agreement between transvagi-nal and transabdominal cervical length measurement after bladder emptying as well as the feasibility of transabdominal sonography in cervical length screening. This was a prospective cohort study involving 287 participants (14-34 weeks' gestation) from January to December 2003. After voiding, transabdominal and transvaginal cervical length measurements were obtained. The optimal trans-abdominal technique was established during an unblinded series of transabdominal and transvaginal cervical length measurements (n = 96). The same measurements were obtained in 191 participants under a blinded 2-sonographer protocol. The transabdominal cervical length cutoff to ensure 100% sensitivity in detecting a short cervix (<or=2.5 cm) was determined. There was no difference between mean transabdominal and transvaginal cervical lengths +/- SD (3.57 +/- 0.74 versus 3.61 +/- 0.74 cm; P = .20). The Pearson correlation coefficient was 0.824. The 95% tolerance interval for any paired observation (transabdominal minus transvaginal) was -0.92 to 0.84 cm. All transvaginal cervical lengths of 2.5 cm or less were associated with paired transabdominal cervical lengths of 3 cm or less. With an optimal sonographic technique, postvoid transabdominal cervical measurement shows a close correlation and agreement with transvaginal assessment and is useful for cervical length screening.

OC101: Transvaginal cervical length measurement as a predictor of preterm delivery in IVF patients

OC101: Transvaginal cervical length measurement as a predictor of preterm delivery in IVF patients

Digital and transvaginal ultrasound cervical assessment for prediction of successful labor induction

Objective To compare the values of preinduction transvaginal cervical length measurements and Bishop score to predict successful labor induction. Methods A prospective, observational trial of nulliparous women undergoing labor induction. Inclusion criteria were gestational age between 36 and 42 weeks, singleton cephalic presentation of the fetus, and intact membranes. Preinduction cervical ripening was performed using 25 μg intravaginal misoprostol (PGE1), repeated every 4 h, up to a maximum of 3 doses. Induction was subsequently continued by oxytocin and amniotomy. Results A total of 43 women met the inclusion criteria. Mean preinduction cervical length for women with successful or failed labor induction was 26 mm (95% Confidence interval [CI], 27–32) and 34 mm (95% CI, 33–38), respectively ( P = 0.002). Mean Bishop scores for successful and failed induction groups were 5.4 (95% CI, 5.2–6.2) and 3.1 (95% CI, 2.8–3.5), respectively ( P = 0.003). Conclusion Digital examination and transvaginal ultrasound of the cervix predict successful labor induction with reasonable accuracy.

Gestational Age at Cervical Length Measurement and Incidence of Preterm Birth

To estimate the risk of spontaneous preterm birth based on transvaginal ultrasound cervical length and gestational age at which cervical length was measured. Women at high risk for spontaneous preterm birth and with transvaginal ultrasound cervical length measurements between weeks 12 and 32 were identified at one institution between July 1995 and June 2005. Inclusion criteria for women at high risk for spontaneous preterm birth were prior spontaneous preterm birth at 14 to 35 weeks, cone biopsy, müllerian anomaly, or two or more dilation and evacuations. Women with multiple gestations, cerclage, indicated preterm birth, or fetal anomalies were excluded. Logistic regression was used to estimate the spontaneous preterm birth risk before 35, 32, and 28 weeks. Seven hundred five women received 2,601 transvaginal ultrasound measurements for cervical length. The incidences of spontaneous preterm birth before 35, 32, and 28 weeks were 17.7, 10.6, and 6.7%, respectively. The risk of spontaneous preterm birth before 35 weeks decreased by approximately 6% for each additional millimeter of cervical length (odds ratio 0.94, 95% confidence interval, 0.92-0.95, P=.001) and by approximately 5% for each additional week of pregnancy at which the cervical length was measured (odds ratio 0.95, 95% confidence interval 0.92-0.98, P=.004). Similar results were obtained for spontaneous preterm birth before 32 and 28 weeks. Gestational age at which transvaginal ultrasound cervical length is measured significantly affects the calculation of risk of spontaneous preterm birth. The spontaneous preterm birth risk increases as the length of the cervix declines and as the gestational age decreases. These spontaneous preterm birth risks are important for counseling and management for women with various degrees of short cervical length at different gestational ages. II.

Ultrasonographic measurement of cervical length in predicting mode of delivery after oxytocin induction

This study was conducted to explore the value of transvaginal ultrasonographic cervical length measurement, in addition to gestational age, maternal age, parity, Bishop score, and weight of the newborn, in predicting the mode of delivery in pregnancies in which labor is induced with oxytocin at or beyond the 40th gestational week. A total of 73 pregnancies at 40 to 42 weeks of gestation were included. After labor was induced, 29 women delivered vaginally and 44 underwent cesarean section. These groups were compared with respect to possible predictive parameters of delivery outcomes. Student t test, Pearson's correlation analysis, and logistic regression analysis were used for statistical evaluation. Mean preinduction cervical length was 26.8+/-9.9 mm in the vaginal delivery group and 34.2+/-8.1 mm in the cesarean section group (P<.05). Mean maternal age, parity, and Bishop score were significantly higher and mean weight of the newborn was significantly lower in the vaginal delivery group. Cervical length measurements showed a significant negative correlation with Bishop scores (r=-.584; P<.05). Logistic regression analysis revealed that Bishop score (likelihood ratio=.472; 95% confidence interval=.338-.658; P<.05) and weight of the newborn (likelihood ratio=1.002; 95% confidence interval=1.00007-1.003; P<.05) were significant independent predictors of the route of delivery. According to the results of this study, maternal age, parity, Bishop score, cervical length, and weight of the newborn all might affect the mode of delivery after labor induction. Bishop score, although a subjective measure, must be considered an important component of preinduction evaluation.

Preterm birth: the value of sonographic measurement of cervical length

Transvaginal ultrasound scanning of cervical length at approximately 20 weeks of gestation in women attending for routine antenatal care is useful for predicting the likelihood of spontaneous early preterm birth. The risk of early birth increases exponentially with decreasing cervical length in both singleton and multiple pregnancies. In such women, individualization of risk would lead to rationalisation of antenatal care, including frequency of visits, patient education in recognising and reporting symptoms of spontaneous preterm labour and timely administration of steroids. It is also possible that in women identified as being at high risk, the rate of preterm birth might be reduced by the prophylactic use of progesterone. In women presenting with threatened spontaneous preterm labour, transvaginal measurement of cervical length provides a useful distinction between those who are likely to deliver within the subsequent 7 days and those who are not. Since only 10-20% of such women are in true spontaneous preterm labour, the cervical length measurement in rational care can avoid the current practice of hospitalisation and administration of steroids and tocolytics to all. This article reviews the evidence in support of the clinical introduction of transvaginal sonography for both the prediction and management of spontaneous preterm labour.

Are novice transvaginal cervical length measurements reliable?

Are novice transvaginal cervical length measurements reliable?

Transvaginal ultrasonographic cervical length measurement as a predictor of successful labor induction

transvaginal ultrasonographic cervical length measurement as a predictor of successful labor induction

Transvaginal cervical length measurement; Its current application in a regional Australian level II maternity hospital

To evaluate the impact of cervical length (CL) measurements in pregnant women at risk for preterm delivery on intervention and pregnancy outcome. Retrospective study. Regional high-level II maternity unit. Hospital databases were reviewed for all women delivering between March 2001 and March 2003. Women at an increased risk for preterm birth with transvaginal (TV) cervical length measurements during pregnancy were included in this audit. Patients (n = 204) were analysed together and in subgroups with different risk profiles. For women with a significant obstetrical history, most of the cervical lengths <or= 2.5 cm were found between 24 and 28 weeks gestational age. None of the patients with twin pregnancy as single indication for cervical length measurements developed a cervical length <or= 2.5 cm. In women with twin pregnancy plus additional risk factor as indication for cervical length measurement, 60.87% showed shortening of cervical length to <or= 2.5 cm. Patients with previous gynaecological operations as the only risk factor had optimal perinatal outcomes. Notwithstanding the potential beneficial effects of therapeutic measures, patients with singleton pregnancies and a significant obstetrical history, and a short cervical length had a relative risk of 3 for preterm delivery. In the group of women presenting with signs and symptoms suggestive of threatening preterm delivery and a short cervical length, significantly more patients were treated with nifedipine compared to similar patients with 'normal' cervical length. For patients with a high-risk obstetrical history, a first cervical length measurement at the time of foetal morphology scan followed by one measurement at about 24 weeks would result in a timely diagnosis of almost all cases of clinically relevant cervical shortening. Just having a twin pregnancy, in the absence of other risk factors for preterm birth, does not require cervical length monitoring. Having a twin pregnancy plus additional risk factors clearly identifies a group requiring cervical length measurement and intervention. Previous LLETZ procedures or >or= 3 preceding curettages were not found to be a major risk factor for preterm birth.

Comparison of transperineal and transvaginal sonography in predicting preterm delivery

A major advantage of transperineal sonography (TPUS) is its ability to evaluate the cervix without causing any distortion. This study was performed to compare transvaginal sonography (TVUS) and TPUS at 24 weeks of gestation in predicting preterm delivery in low-risk pregnancy. Three hundred fifty-seven pregnant women underwent TVUS and TPUS at 24 weeks of gestation. The relationship between cervical length and preterm delivery was assessed. Accuracy values of TVUS and TPUS at 24 weeks of gestation were compared in predicting preterm delivery. Preterm delivery (before 36 weeks of gestation) occurred in 22 pregnancies (6.2%). Mean cervical lengths measured by TVUS and TPUS were significantly different in preterm and term delivery groups (P < 0.05). Areas under the curves were 0.801 and 0.857 for the transvaginal and transperineal measurements, respectively. The coefficient of correlation between the transvaginal and transperineal cervical length measurements was 0.83. TPUS had a sensitivity of 77% in predicting preterm delivery, with a false-positive rate of 17% and a relative risk of 4.5 at the 32.5-mm cutoff value. When the cervix is well visualized, TPUS can predict preterm delivery as accurately as TVUS.

Accuracy of cervical transvaginal ultrasonography in predicting preterm birth: a systematic review

To determine the accuracy with which transvaginal cervical ultrasonography predicts spontaneous preterm birth, studies were identified, without language restrictions, through nine different databases (1966–2002) and manual searching of bibliographies of known primary and review articles. Studies were selected if they undertook transvaginal ultrasonographic cervical length measurement among a population of pregnant women antenatally and had known gestation at delivery. Data were extracted for studies’ characteristics, quality and accuracy results for < 32, < 34 and < 37 weeks’ gestation outcome as the reference standards. Data were stratified according to singletons or twins, gestational age at testing, cervical length thresholds and the various reference standards. Data were pooled to produce summary estimates of likelihood ratios (LRs). Forty-six primary articles included a total of 31 577 women, consisting of 33 studies in asymptomatic and 13 studies in symptomatic women. There was a wide variation among studies with respect to gestational age at testing, definition of threshold for abnormality and definition of reference standard. The most commonly reported subgroup was testing of asymptomatic women at 20–24 weeks’ gestation using a threshold of 25 mm with spontaneous preterm birth before 34 weeks’ gestation as the reference standard. The summary LR+ for this group was 4.44 (95% confidence interval (CI) 3.23–6.08), with corresponding LR− of 0.68 (95% CI 0.49–0.94).

Reference range for cervical length in twin pregnancies.

Twin pregnancies are at increased risk of preterm delivery, and cervical length measurement by transvaginal ultrasound examination has been shown to be an effective method of screening for this complication. The aim of the present study is to establish a reference range for cervical length measurement throughout gestation in twin pregnancies. Prospective study involving 144 nonselected twin pregnancies that delivered after 34 weeks and underwent ultrasound examination every 4 weeks for transvaginal measurement of cervical length. Mean cervical length measurements, 95% confidence intervals for the estimate and 95% prediction intervals were established throughout gestation by linear regression analysis. There was a significant correlation between cervical length measurements and gestational age [cervical length (mm) = - 0.758 * gestation age (weeks) + 56.69, r=- 0.43, p < 0.0001], and mean cervical length shortened by approximately 0.8 mm per week, from 47 mm at 13 weeks to 32 mm at 32 weeks. The corresponding lower limits for the 95% prediction intervals were 29 and 15 mm, respectively. Cervical length shortens gradually throughout gestation in twin pregnancies.

Effect of cerclage on obstetrical outcome in twin gestations with a shortened cervical length

Objective: Our purpose was to determine the impact of cerclage placement on obstetric outcome in twin gestations with a shortened cervical length. Study design: A prospective cohort study of 147 consecutive twin pregnancies (July 1994 to March 2001) who underwent transvaginal ultrasonographic cervical length measurement between 18 and 26 weeks' gestation. Cerclage was offered to women with cervical lengths ≤25 mm. Patients were segregated into quartiles by cervical length. Regression analysis and χ2 tests were used to determine the effect of cervical length and cerclage on parameters of prematurity. Results: One hundred twenty-eight twin gestations met inclusion criteria, including 21 (16.4%) who underwent cerclage for a cervical length ≤25 mm. Decreasing cervical length was significantly associated with a shorter length of gestation, lower combined birth weight, delivery at ≤34 weeks, preterm premature rupture of fetal membranes, and very low birth weight. None of these outcomes was altered by cerclage placement. Conclusion: Midtrimester cerclage does not alter the risks of prematurity associated with a shortened cervical length in twin gestations. (Am J Obstet Gynecol 2002;186:634-40.)

Reversal of asymptomatic cervical length shortening with cervical cerclage: a preliminary study.

This is a prospective observational study which highlights the value of serial transvaginal cervical length measurements to identify asymptomatic cervical length shortening and the effect on cervical length following insertion of a McDonald cerclage. Four out of 14 patients exhibited asymptomatic cervical length shortening. Only patients whose cervical length was <2 cm underwent cerclage. All patients showed an increase in cervical length post-cerclage. The possible mechanisms responsible for these changes are discussed.

Cervical length at 16–22 weeks’ gestation and risk for preterm delivery

Objective: To determine whether cervical length, as measured by transvaginal sonogram in asymptomatic gravidas at 16–22 weeks, is associated with risk of spontaneous preterm delivery. Methods: In a prospective observational study in an unselected urban tertiary care population, cervical length was measured by transvaginal ultrasound during routine anatomic surveys in 760 gravidas at 16 0/7 to 22 6/7 weeks. The predictor variable was cervical length and the outcome variable was gestational age at delivery. Care providers were not masked to the results. Spontaneous preterm delivery was analyzed as before 37, 35, and 32 weeks. Shortened cervical length was defined by the tenth, fifth, and two and a half percentiles for our population. Yates-corrected χ 2 was used to evaluate the significance on univariate analysis of the relative risk (RR) and 95% confidence intervals (CI). Multiple logistic regression analysis was used to control for background variables in evaluating the probability of preterm delivery at less than 35 weeks. Sensitivity, specificity, positive and negative predictive values also were calculated. Results: Cervical lengths were normally distributed (mean 38.5 ± 8.0 mm at 19.9 ± 1.5 weeks) independent of gestational age at measurement, and the tenth, fifth, and two and a half percentiles were 30, 27, and 22 mm, respectively. Eighty-five women delivered before 37 weeks, 51 before 35 weeks, and 27 before 32 weeks. Relative risks (95% CI) for spontaneous preterm delivery before 37 weeks were 3.8 (2.6, 5.6), 5.4 (3.3, 9.0), and 6.3 (3.0, 13.0) for the tenth, fifth, and two and a half percentiles, respectively; RRs for before 35 weeks were 4.5 (2.9, 6.9), 7.5 (4.5, 12.5), and 7.8 (3.6, 16.7); and for before 32 weeks were 5.2 (3.3, 8.3), 9.7 (5.8, 16.1), and 8.4 (3.6, 19.9), respectively. Multiple logistic regression analysis confirmed that cervical length was a significant predictor of preterm birth before 35 weeks, and that paras had a 43% greater risk compared with nulliparas. Sensitivity ranged from 13–44%, specificity 90–99%, positive predictive value 15–47%, and negative predictive value 80–98%. Conclusion: Transvaginal measurement of cervical length during routine ultrasound at 16–22 weeks’ gestation in asymptomatic gravidas might help identify women at risk for spontaneous preterm delivery.

Pitfalls in Ultrasonic Cervical Length Measurement for Predicting Preterm Birth

In Brief Objective To describe the anatomic and technical difficulties encountered with transvaginal ultrasound imaging of the cervix in a consecutive series of women at risk for preterm delivery. Methods Three groups of women had cervical ultrasound examinations: those with histories of preterm birth, those with incompetent cervices, and those admitted for preterm labor that did not progress. Standardized ultrasound examinations of the cervix involved measuring the length of the endocervical canal, funneling length, and internal os dilation with and without fundal pressure. Results Sixty consecutive women had transvaginal ultrasound examinations for assessment of the cervix. Forty-six had histories of preterm birth, five had incompetent cervices, and nine had arrested preterm labor. Six types of problems arose, which can be divided into anatomic or technical considerations, with an overall frequency of 27% (95% confidence interval 16%, 40%). Anatomic pitfalls that hampered identification of the internal os included an undeveloped lower uterine segment (n = 5), a focal myometrial contraction (n = 1), rapid and spontaneous cervical change (n = 1), and an endocervical polyp (n = 1). Technical pitfalls included incorrect interpretation of internal os dilation because of vaginal probe orientation (n = 7) and artificial lengthening of the endocervical canal because of distortion of the cervix by the transducer (n = 1). Conclusion We caution those who perform cervical length examinations to be wary of falsely reassuring findings due to potential anatomic and technical pitfalls. Anatomic and technical pitfalls can lead to faulty interpretation of transvaginal ultrasonic cervical length measurements.