Cervical incompetence: the use of transvaginal sonography to provide an objective diagnosis.

OBJECTIVE: To investigate the use of transvaginal sonography in monitoring the cervix in women at high risk of a preterm delivery. STUDY DESIGN: One hundred and six women at high risk of preterm labor had regular cervical monitoring by transvaginal ultrasound throughout pregnancy from the second trimester to delivery. The study was designed to be observational, but intervention was considered if the cervical length fell below 10 mm. RESULTS: Eleven women demonstrated opening of the cervical canal at rest or with fundal pressure before 24 weeks' gestation. Between 2 and 17 days later all 11 cervices progressively shortened to a cervical length of < 10 mm. Nine women had a cervical cerclage. Seven women had fetal membranes visible within the cervical canal at the time of cerclage. One woman miscarried at 18 weeks, and the other 10 had live births at a median gestational age of 36 (range, 27-38) weeks. CONCLUSIONS: Cervical length shortening in the second trimester, once started, progressed to a cervical length under 10 mm. Opening of the cervical os at rest or in response to fundal pressure detected by transvaginal ultrasound appears to be the early ultrasound feature of cervical incompetence.     

Does transvaginal sonographic measurement of cervical length before 14 weeks predict preterm delivery in high-risk pregnancies?

OBJECTIVE: To determine whether high-risk patients manifest cervical length < 25 mm on transvaginal ultrasound before 14 weeks of gestation, and if this finding is predictive of preterm delivery. METHODS: Asymptomatic pregnancies at high risk for preterm birth were followed prospectively from 10 + 0 weeks to 13 + 6 weeks with transvaginal sonographic measurement of the cervix. A cervical length < 25 mm was considered a short cervix at this gestational age and at the follow-up ultrasound examinations, performed between 14 and 24 weeks. The primary outcome was preterm birth at < 35 weeks of gestation. RESULTS: One hundred and eighty-three pregnancies met the study criteria and were included in the analysis. Only 10 (5%) patients had a cervix < 25 mm before 14 weeks. The sensitivity, specificity and positive and negative predictive values of a short cervix were 14%, 97%, 50%, and 82%, respectively (relative risk, 2.8; 95% confidence interval, 1.4-5.6). The mean transvaginal sonographic cervical length before 14 weeks of gestation was 33.7 +/- 6.9 mm in pregnancies which delivered preterm (n = 36), and 35.0 +/- 6.8 mm in those delivering at term (n = 147) (P = 0.3). Follow-up transvaginal ultrasound examination of the cervix to 24 weeks revealed that the average gestational age at which a short cervix was detected was 18.7 +/- 2.9 weeks. CONCLUSION: A cervical length < 25 mm on transvaginal sonographic assessment rarely occurs before 14 weeks even in high-risk patients destined to deliver preterm; in these patients cervical changes predictive of preterm birth develop mostly after this gestational age.     

Elective cerclage vs. ultrasound-indicated cerclage in high-risk pregnancies.

OBJECTIVE: To compare pregnancy outcome after elective vs. ultrasound-indicated cervical cerclage in women at high risk of spontaneous mid-trimester loss or early preterm birth. METHODS: This was a retrospective study comparing two management strategies in women with singleton pregnancies who had at least one previous spontaneous delivery at 16-33 weeks of gestation. One group was managed by the placement of an elective cerclage at 12-16 weeks and the other group had transvaginal ultrasound examinations of the cervix at 12-15+6, 16-19+6, and 20-23+6 weeks and cervical cerclage was carried out if the cervical length was 25 mm or less. RESULTS: A total of 90 patients were examined, including 47 that were managed expectantly and 43 treated by elective cerclage. In the expectantly managed group, 59.6% (28/47) required a cervical cerclage. We excluded from further analysis three patients who were lost to follow-up and three because of fetal death or iatrogenic preterm delivery. Miscarriage or spontaneous delivery before 34 weeks' gestation occurred in 14.6% (6/41) of the elective cerclage group, compared with 20.9% (9/43) in the expectantly managed group (chi2 = 0.219, P = 0.640). CONCLUSION: In women at increased risk of spontaneous mid-trimester or early preterm delivery, a policy of sonographic surveillance followed by cervical cerclage in those with a short cervix reduces the need for surgical intervention without significantly increasing adverse pregnancy outcome.     

Early prediction of preterm delivery by transvaginal ultrasonography.

The clinical value of transvaginal ultrasonography in the evaluation of the uterine cervix of pregnant women was studied. Comparison with conventional transabdominal ultrasound in 24 pregnant subjects revealed that transvaginal ultrasound was superior, because the transabdominal technique usually requires a full bladder, which causes deformation and elongation of the cervix. Digital examination showed dilatation of the internal os in only ten (38.5%) of 26 patients in whom it had previously been shown by transvaginal sonography. Transvaginal ultrasonography has the advantage of providing natural and objective information on the cervix. The values of three sonographic signs found transvaginally for predicting preterm delivery were evaluated in a total of 130 at-risk patients and 129 control subjects. Shortening of the cervical length by -1.5 SD or more was associated with an increased risk of preterm delivery (11.3% vs. 2.8%, p < 0.01). A dilated internal os of more than 5 mm before 30 weeks of gestation was associated with preterm delivery more often than an undilated internal os (33.3% vs. 3.5%, p < 0.01). Dynamic changes in the degree of dilatation of the cervical canal which were found in nine women were significantly related with preterm delivery (p < 0.05). But, in the at-risk group, only dilatation of the internal os had a predictive value for preterm birth. From these data, dilatation of the internal os on transvaginal ultrasonography was proved to be an early and important predictor of preterm delivery.     

A comparison of sonographic cervical parameters in predicting spontaneous preterm birth in high-risk singleton gestations.

OBJECTIVES: To assess the role of cervical sonography and to compare various sonographic cervical parameters in their ability to predict spontaneous preterm birth in high-risk singleton gestations. DESIGN: A prospective cohort of 469 high-risk gestations were longitudinally evaluated between 15 and 24 weeks' gestation on 1265 occasions with transvaginal cervical sonography and transfundal pressure. The cervical parameters obtained were funnel width and length, cervical length, percent funneling and cervical index. The information obtained was used for patient management. Restriction of physical activities was initiated at cervical lengths of < or = 2.5 cm with cerclage as an option for cervical lengths of < or = 2.0 cm. RESULTS: Receiver operating characteristic curve analyses showed that a cervical length of < or = 2.5 cm between 15 and 24 weeks' gestation was equal to the other sonographic cervical parameters in its ability to predict spontaneous preterm birth. The sensitivities for delivery at < 28, < 30, < 32 and < 34 weeks' gestation were 94%, 91%, 83% and 76%, respectively, while the negative predictive values were 99%, 99%, 98% and 96%, respectively. The placement of a cerclage did not influence the positive and negative predictive values. In comparison to women with other risk factors, cervical length was best in the prediction of preterm birth in women with a prior mid-trimester loss; an optimal cut-off of < or = 1.5 cm had sensitivities for delivery at < 28, < 30, < 32 and < 34 weeks' gestation of 100%, 100% 92% and 81%, respectively. The rate of preterm delivery at < 34 weeks' gestation increased dramatically when the cervical length was < or = 1.5 cm. Cervical length was the only independent variable that entered the logistic regression model for the prediction of preterm delivery at < 34 weeks' gestation. CONCLUSIONS: In high-risk singleton gestations a cervical length of < or = 2.5 cm was equal to other sonographic cervical parameters in its ability to predict spontaneous preterm birth and was better for the prediction of earlier forms of prematurity (at < 28 and < 30 weeks) than later forms (at < 32 and < 34 weeks). The optimal cervical lengths and their performance for predicting prematurity may be influenced by obstetric risk factors.     

The implications of sonographically identified cervical changes in patients not necessarily at risk for preterm birth.

Sonography of the cervix and lower uterine segment has been used in evaluating pregnancies at risk for incompetent cervix and premature labor. Shortened cervix (less than 3 cm) and open internal os with funneling of the membranes into the endocervical canal are sonographic features associated with premature delivery. We identified these sonographic signs in a group of 31 asymptomatic women who were undergoing prenatal sonography for multiple indications, not necessarily related to premature labor or cervical incompetence. Nineteen patients (61%) in this heterogeneous population had pregnancies complicated by preterm labor, clinical evidence of incompetent cervix, or preterm birth. We conclude that the presence of abnormal sonographic features of the cervix seen incidentally during prenatal sonography on asymptomatic patients warrants close clinical attention.     

Funneling to the stitch: an informative ultrasonographic finding after cervical cerclage.

OBJECTIVE: The purpose of this study was to evaluate the utility of ultrasound surveillance after cerclage placement and to propose a rationale for cervical sonography in this setting. SUBJECTS AND METHODS: This was a retrospective analysis of 53 women undergoing cervical cerclage by a maternal-fetal medicine specialist, regardless of indication, and delivering between January 1999 and April 2001. Transvaginal ultrasonographic assessment of cervical length and the degree of cervical funneling after cerclage were compared to preoperative values and to outcomes including gestational age at delivery. Funneling to the cerclage was defined as membranes prolapsing down the endocervical canal until they reached the plane of the cerclage. RESULTS: Cervical cerclage resulted in a significant increase in cervical length from 2.1 +/- 1.2 cm to 2.9 +/- 0.8 cm after the procedure, P < 0.001; however, this measure was not correlated with gestational age at delivery. Funneling to the level of the cerclage was associated with an earlier gestational age at delivery 31.3 +/- 5.6 weeks vs. 36.8 +/- 2.8 weeks for those cases without this finding, P < 0.001. A statistically significant association between funneling to the cerclage and preterm delivery was identified irrespective of the indication (prophylactic or emergency) for the procedure. When descent of the membranes to the level of the cerclage was noted, it occurred by 28 weeks' gestation in all patients studied. The incidence of premature rupture of the membranes was also significantly greater postcerclage in women with descent of the membranes to the cerclage (52%) compared to those without this finding (9%) P= 0.002. CONCLUSIONS: Funneling to the cerclage is significantly associated with earlier preterm delivery in patients who have undergone cervical cerclage. Serial sonography up to 28 weeks' gestation is useful in identifying patients at higher risk for premature rupture of the membranes and preterm delivery.     

Cervical length evaluation by transvaginal sonography in nongravid women with a history of preterm delivery.

OBJECTIVE: To evaluate cervical length in the nongravid period in women with a past history of preterm delivery. METHODS: The study population comprised 54 women who had delivered spontaneously before 34 weeks of gestation. Etiology of preterm delivery was suspected to be related to cervical incompetence, defined as a painless and progressive dilatation of the cervix in the absence of other causes. Patients with pre-eclampsia, intrauterine growth restriction, uterine anomalies, fetal anomalies, multiple gestation and similar complications were excluded. Shortening of the cervix was recorded during pregnancy in all study patients. One hundred and four women matched for age, parity and body mass index who had given birth at term served as the control group. Cervical length was evaluated in all women at least 12 weeks after delivery by transvaginal sonography in the mid-sagittal plane. RESULTS: The mean gestational age at delivery was 30.8 +/- 1.2 weeks in the study group and 38.8 +/- 2.1 weeks in the control group (P = 0.03). The mean cervical length in the two groups was 36 +/- 6 and 38 +/- 4 mm, respectively. This difference was not statistically significant (P = 0.9). CONCLUSIONS: In nongravid women with unexplained preterm delivery there is no difference in cervical length compared to patients who deliver at term. Shortening of the cervix is most probably a reversible phenomenon that occurs during pregnancy and represents a failure of the competence mechanism to adapt to pregnancy.     

Comparison of transperineal and transvaginal sonography in predicting preterm delivery

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: When the cervix is well visualized, TPUS can predict preterm delivery as accurately as TVUS.     

Cervical assessment at the routine 23-weeks' scan: problems with transabdominal sonography.

OBJECTIVES: To compare transabdominal and transvaginal sonographic measurements of cervical length in pregnancy and examine the factors that may influence these measurements. METHODS: The study population consisted of 149 women with singleton pregnancies attending for routine ultrasound examination at 23 weeks of gestation. In all women the cervix was successfully visualized by transvaginal sonography and cervical length was measured after emptying of the bladder. This measurement was compared to that obtained by transabdominal sonography. In addition the ability to visualize the cervix transabdominally was examined in relation to body mass index (BMI), bladder volume and cervical length. RESULTS: The percentage of cases in which the cervix could be seen transabdominally increased from 42% for bladder volume of < 50 ml to 73% for volumes > 150 ml, and 13% for cervical length < 20 mm to 51% for lengths > 40 mm. The ability to visualize the cervix was unrelated to BMI. Although there was a significant association between measurements taken transabdominally with those made transvaginally, measurements taken with a full bladder were significantly longer than those with an empty bladder. CONCLUSION: The aim of cervical assessment in pregnancy is to identify women with a short cervix because they are at high risk of preterm delivery. This aim can not be fulfilled by transabdominal sonography. Such a scan fails to visualize the cervix in a high proportion of cases and in particular those with a short cervix. Furthermore, successful visualization requires a full bladder which falsely increases cervical length.     

Cervical length for prediction of preterm birth in women with multiple prior induced abortions.

OBJECTIVE: To determine whether transvaginal sonographic cervical length predicts preterm birth in women with multiple prior induced abortions. METHODS: This was a retrospective cohort study using the Thomas Jefferson University Prematurity Database. Patients with a singleton pregnancy and a history of more than one induced abortion were identified. Exclusion criteria were cerclage and indicated preterm birth. Subjects were followed with transvaginal ultrasound measurement of the cervix between 14 and 24 weeks' gestation and grouped into those with and those without a short cervix; a cervical length of < 25 mm was considered short. The primary outcome was spontaneous preterm birth at < 35 weeks. RESULTS: Fifteen of the 65 (23%) women with more than one induced abortion included in the study had a short cervix. The demographics and risk factors were similar between those with and those without a short cervix. The overall incidence of preterm birth was 21.5% (14/65); in women with a short cervix the incidence was 47% (7/15) and in women without a short cervix it was 14% (7/50). The sensitivity, specificity and positive and negative predictive values of a short cervix in the prediction of preterm birth were 50%, 84%, 47% and 86%, respectively. The relative risk of a short cervix for spontaneous preterm birth was 3.3 (95% CI, 1.4-7.4). CONCLUSION: A cervical length of < 25 mm on transvaginal ultrasound is predictive of preterm birth in women with more than one prior induced abortion. Women with multiple prior induced abortions and a short cervix have a 3.3-fold greater chance of spontaneous preterm birth compared with those with a cervical length of > or = 25mm.     

Cervical length and funneling at 23 weeks of gestation in the prediction of spontaneous early preterm delivery.

OBJECTIVES: To establish the relationship of cervical length at 23 weeks of gestation to the risk of spontaneous delivery before 33 weeks and to determine the possible additional risk if funneling is present. METHODS: During a 36-month period, 6819 women with singleton pregnancies underwent transvaginal sonographic cervical assessment at 22-24 weeks as a screening test for preterm delivery. The distribution of cervical length and the prevalence of funneling, defined as dilatation of the internal os of > or = 5 mm in width, were established. Women who underwent cervical cerclage, iatrogenic preterm delivery or were lost to follow-up were excluded from further analysis. In the remaining 6334 pregnancies, logistic regression was used to examine the contribution of cervical length and funneling to the risk of spontaneous preterm delivery before 33 weeks. RESULTS: The median cervical length was 36 mm and in 1.6% of cases the length was < or = 15 mm. There was a significant inverse association between cervical length and percentage rate of spontaneous delivery before 33 weeks. Funneling of the internal os was present in about 4% of pregnancies and the prevalence decreased with increasing cervical length from 98% when the length was < or = 15 mm to about 25% for lengths of 16-30 mm and less than 1% at lengths of > 30 mm. The rate of preterm delivery was 6.9% in those with funneling compared to 0.7% in those without funneling (chi2 = 86.7; P < 0.0001). However, logistic regression analysis demonstrated that funneling did not provide a significant additional contribution to cervical length in the prediction of spontaneous delivery before 33 weeks (odds ratio for short cervix = 24.9, Z = 4.43, P < 0.0001; odds ratio for funneling = 1.8, Z = 0.84, P = 0.40). CONCLUSION: In the prediction of preterm delivery, funneling does not provide any significant contribution in addition to cervical length.     

Cervical Incompetence Prevention Randomized Cerclage Trial (CIPRACT): effect of therapeutic cerclage with bed rest vs. bed rest only on cervical length.

OBJECTIVE: To compare the effects of therapeutic cerclage and bed rest vs. just bed rest on cervical length and to relate these effects to the risk of preterm delivery. DESIGN: Cervical length was measured in patients at high risk of cervical incompetence. When a cervical length < 25 mm was measured before 27 weeks' gestation, randomization for therapeutic cerclage and bed rest vs. just bed rest was performed. After randomization, cervical length was measured weekly. For statistical analysis, t-test and Fisher's exact tests were used and P < 0.05 was considered statistically significant. RESULTS: Nineteen women were randomly allocated to receive a therapeutic cerclage and bed rest and 16 were allocated to receive bed rest only. Mean cervical lengths and mean gestational ages before randomization were comparable between both groups, overall 19.8 mm and 20.7 weeks. Cervical length was measured again at a mean gestation of 22.1 weeks. Mean cervical length (31 mm) was significantly (P < 0.0001) longer after cerclage than after bed rest only (19 mm). A cervical length > or = 25 mm was measured in 22 of the 35 included women, 16 in the cerclage group and six in the bed-rest group (P = 0.006). Of these 22 women, only one delivered before 34 weeks' gestation, which was significantly less frequent than six out of 13 women with a cervical length < 25 mm (P = 0.006). CONCLUSIONS: Therapeutic cerclage with bed rest increases cervical length more often than bed rest alone. A postintervention cervical length > or = 25 mm reduces the risk of preterm delivery in women at high risk of cervical incompetence and a preintervention cervical length < 25 mm.     

经阴道超声监测孕妇宫颈形态预测早产的价值

目的评价经阴道超声监测宫颈形态变化对早产的预测价值。方法 223例孕妇分为足月分娩组134例和先兆早产组89例,分别于孕24、28、32及36周行经阴道超声检查,观察宫颈形态长度的变化,以及宫颈指数,并对其妊娠结局进行随访。结果足月分娩组中宫颈长度随孕周增大而缩短;先兆早产组孕妇的宫颈长度均较相应孕周的足月分娩组短,其中24、28及36周组间比较,差异有统计学意义(P<0.05)。先兆早产组各孕周的宫颈指数均较足月分娩组大,两组比较差异有统计学意义(P<0.05)。89例先兆早产组中71例保胎成功,18例发生早产。先兆早产组中21例有宫颈漏斗形成,18例早产者均有宫颈漏斗形成。漏斗形成预测早产的敏感性为100%、特异性为96.6%;以足月分娩孕妇28周时的宫颈长度2.61cm为临界值,其预测早产的敏感性为83.3%、特异性为100%。结论经阴道超声实时监测宫颈形态结构变化对预测早产的发生有一定的临床价值。     

Evaluation of the upper uterine cervix by the location of the vesicocervical fold of the urinary bladder to rule out cervical shortening during pregnancy with and without premature contractions.

OBJECTIVES: To measure the length of the upper and lower cervix, as demarcated anatomically by the lowermost edge of the urinary bladder, in second- and third-trimester pregnancies with and without premature contractions. We hypothesized that patients with active premature contractions have a shorter upper cervix, placing them at greater risk of preterm delivery. METHODS: The lengths of the total cervix and of the upper and lower cervix, separately, and funnelling of the internal os, were assessed by endovaginal ultrasonography. In 120 women with normal pregnancy (43 of which with premature contractions), cervical dilatation and effacement were determined by digital examination. The correlation of cervical variables with the course of pregnancy was analyzed by the Wilcoxon test. RESULTS: The mean lengths of the upper and lower cervix were 15.9 +/- 1.7 mm (median 16.0 mm) and 26.4 +/- 3.7 mm (median 27.0 mm), respectively, in patients without premature contractions and 6.9 +/- 3.7 mm (median 6.0 mm) and 24.7 +/- 4.7 mm (median 25.0 mm), respectively, in patients with premature contractions. In the latter subgroup, the upper cervix was significantly shorter (p = 0.0001) but the lower cervix remained almost unchanged. Digital palpation was less accurate than transvaginal sonography for evaluating total cervical length. CONCLUSIONS: Transvaginal sonography is the method of choice for assessing cervical changes during pregnancy. In this prospective study, upper cervical length was the best predictor of preterm labor of all cervical parameters studied. Its length could be accurately determined by the location of the lowermost edge of the urinary bladder (vesicocervical fold of the bladder).     

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

This review investigates the accuracy with which transvaginal cervical sonography predicts spontaneous preterm birth. Published studies were identified without language restrictions through nine different databases and manual searching of bibliographies of known primary and review articles. Studies were selected if they undertook antenatal transvaginal sonographic cervical assessment among a population of pregnant women with known gestational age of delivery. There were 46 primary articles, which included a total of 31,577 women, consisting of 33 studies in asymptomatic and 13 studies in symptomatic women. Data were extracted for the studies' characteristics and quality. Accuracy data were used to form 2 x 2 contingency tables for various cervical length measurements with birth before 32, 34 and 37 weeks' gestation as the reference standards. Data were stratified according to singleton or twin pregnancy, gestational age at testing, cervical length threshold, and the various reference standards, and were pooled to produce summary estimates of likelihood ratios (LRs). Our review showed that transvaginal cervical sonography identifies women who are at higher risk of spontaneous preterm birth, although there was a wide variation amongst studies with respect to gestational age at testing, definition of threshold of abnormality and definition of reference standard. The most commonly reported sub-group was testing of asymptomatic women at < 20 weeks' gestation using a threshold cervical length of 25 mm with spontaneous preterm birth before 34 weeks' gestation as the reference standard. The summary LR+ for this group was 6.29 (95% CI, 3.29-12.02), with corresponding LR- of 0.79 (95% CI, 0.65-0.95). Both cervical length measurement and funneling, whether alone or in combination, appear to be useful (depending on the threshold chosen to define the abnormality) in predicting spontaneous preterm birth in asymptomatic women. For symptomatic women there was a paucity of data, although the degree of funneling appeared to be predictive of spontaneous preterm birth.     

Does transvaginal ultrasound of the cervix predict preterm premature rupture of membranes in a high-risk population?

OBJECTIVES: To determine in patients with a cervical length < 25 mm on transvaginal ultrasound if the severity of cervical length shortening can be used to predict preterm premature rupture of membranes (PPROM) and the contribution of PPROM to preterm delivery in these patients. METHODS: We retrospectively reviewed asymptomatic singleton pregnancies between 14 and 24 weeks at high risk of preterm delivery by obstetric history and transvaginal cervical length < 25 mm. Cases developing subsequent PPROM were compared with controls for transvaginal sonographic cervical characteristics. RESULTS: Of 69 patients identified to have a cervical length < 25 mm, 27 (39%) had PPROM, and 42 (61%) did not. Mean +/- standard deviation (SD) cervical length was 12.7 +/- 8.7 mm and 17.0 +/- 7.6 mm in the two groups, respectively (P = 0.04). Mean +/- SD cervical funneling was 57.4 +/- 31.4% and 40.0 +/- 28.1%, respectively (P = 0.01). The characteristics most predictive of PPROM were: cervical length of < 10 mm (sensitivity, specificity, positive and negative predictive values of 33, 90, 69, and 68%, respectively; odds ratio, 4.8; 95% confidence interval, 1.3-17.5) and cervical funneling > 75% (sensitivity, specificity, positive and negative predictive values of 33, 93, 75 and 68%, respectively; odds ratio, 6.5; 95% confidence interval, 1.6-26.9). Stepwise logistic regression revealed cervical length to be a significant predictor of PPROM (odds ratio, 4.0; 95% confidence interval, 1.1-14.2). CONCLUSION: In patients at high risk for preterm delivery because of obstetric history and transvaginal sonographic cervical length < 25 mm, a cervical length < 10 mm and cervical funneling > 75% were most predictive of PPROM. PPROM was the major contributor to preterm delivery in these patients.     

Transvaginal sonography of the uterine cervix prior to labor induction.

OBJECTIVES: To compare the Bishop score and transvaginal sonographic measurement of cervical length for predicting the mode of delivery following medically indicated induction of labor in term patients. METHODS: The study was conducted prospectively in 179 women who required medically indicated induction of labor. Inclusion criteria were singleton pregnancy, gestational age > 37 weeks of amenorrhea, cephalic presentation and intact fetal membranes. Cervical length was measured upon arrival in the labor room but was not considered when choosing the induction procedure. Two receiver-operating characteristic curves were plotted to calculate the best threshold value for the Bishop score and for cervical length for predicting the risk of Cesarean section. RESULTS: Fifty-three women (29.6%) had a Cesarean section. The Bishop score was not predictive of the delivery mode, although Cesarean section for failure to progress was more frequent when the Bishop score was < or = 5. Among the women with a Bishop score > 5, the cervical length was not predictive of the induction outcome. However, among the women with a Bishop score < or = 5, a cervical length < 26 mm was associated with a lower Cesarean section rate (20.6 vs. 42.9%; P = 0.006). Furthermore, the interval between the beginning of cervical ripening and delivery was shorter in the case of a short cervix (11.01 +/- 6.7 vs. 18.55 +/- 7.07 h; P < 10(-5)). CONCLUSION: The length of the uterine cervix, measured by transvaginal sonography, is a better predictor of the risk of Cesarean section than the Bishop score after induction of labor for medical reasons. In women with an unfavorable Bishop score, a cervical length of < 26 mm is associated with a lower risk of Cesarean section and a shorter duration of labor.     

Prediction of preterm birth by second trimester cervical sonography in twin pregnancies.

OBJECTIVES: To determine the predictive value of sonographic cervical length and of funneling for spontaneous preterm delivery (PTD) in twin pregnancies under 26 weeks' gestation. METHODS: Women with twin pregnancies were studied prospectively with transvaginal or translabial ultrasound of the cervix from 18 to 26 weeks' gestation. Exclusion criteria were: signs of preterm labor, prophylactic cervical cerclage, placenta previa, or severe congenital fetal anomaly. The primary outcome was spontaneous preterm birth at < 35 weeks' gestation. RESULTS: Sixty-five twin pregnancies were analyzed, of which 23% (15/65) delivered preterm. Cervical ultrasound examination was performed by 22 weeks' gestation in 75% and by 24 weeks' gestation in 91% of women. Cervical length < or = 25 mm and < or = 30 mm was associated with sensitivities of 27% and 53%, respectively, and with 67% and 62% rates of PTD, respectively (R.R. 4.6, C.I. 2.0-10.3 and R.R. 3.6, C.I. 1.6-7.8, respectively). A cervical length > 35 mm was associated with only a 4% rate of PTD (R.R 0.13; C.I. 0.02-0.93). Of 10 women (15%) with any cervical funneling, 70% delivered preterm, all under 32 weeks' gestation. By logistic regression analysis, both short cervix < or = 30 mm and any funneling were strongly predictive of PTD. CONCLUSIONS: Both cervical length < or = 30 mm and cervical funneling in twin pregnancies under 26 weeks' gestation are independently and strongly associated with high risk for preterm birth. A long cervix, of length > 35 mm, is associated with very low risk (4%) for preterm birth.     

Predicting preterm delivery in asymptomatic patients with prior preterm delivery by measurement of cervical length and phosphorylated insulin-like growth factor-binding protein-1.

OBJECTIVE: To evaluate the efficacy of cervical length measurement in combination with a bedside assessment of phosphorylated insulin-like growth factor-binding protein-1 (phIGFBP-1) as a predictor of preterm delivery in asymptomatic pregnant women with a history of preterm birth. METHODS: Cervical length was measured using transvaginal sonography at 22-24 weeks of gestation in 105 singleton pregnancies and a rapid strip test was performed to detect phIGFBP-1 in cervical secretions from 24 to 34 weeks. Receiver-operating characteristics (ROC) curves were constructed to compare the performance of phIGFBP-1 at different gestational ages, and cervical length at 22-24 weeks, in predicting preterm delivery. RESULTS: The rate of spontaneous delivery before 37 and 34 weeks was 23.8% and 11.4%, respectively. Women with cervical lengths less than 20 mm had a risk of spontaneous preterm delivery before 34 and 37 weeks of 43.5% and 69.6%, respectively. The performance of phIGFBP-1 levels as a predictor of preterm delivery was significantly higher when the test was carried out at 30 weeks' gestation. Cervical assessment in combination with phIGFBP-1 at 30 weeks had the steepest ROC curve (area under the curve=0.93; 95% CI, 0.88-0.98, P<0.001). CONCLUSION: Both cervical length and phIGFBP-1 measurement are useful in the prediction of preterm delivery in patients with a history of preterm birth and the combined method of measuring cervical length at 22-24 weeks and phIGFBP-1 at 30 weeks improves upon either method used alone.