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.     

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.     

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.     

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.     

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.     

Serial translabial sonographic measurement of cervical dimensions between 24 and 34 weeks' gestation in pregnant Thai women.

OBJECTIVE: To assess serial changes of cervical dimensions in pregnant Thai women between 24 and 34 weeks' gestation by translabial sonography. METHODS: A longitudinal study of cervical dimensions obtained by translabial sonography at 24, 28, 30, 32, and 34 weeks' gestation in 144 women was conducted. The gestational age at labor was recorded and women were defined as having preterm labor or term labor according to whether there was onset of true labor pain before or after 37 completed weeks, respectively. Cervical changes over time were analyzed by repeated ANOVA. The associations between cervical dimensions and gestational age, parity and prepregnancy body mass index were calculated by multiple linear regression analysis. RESULTS: Cervical length decreased whereas cervical width increased as gestational age advanced. Cervical length and width in women with term labor, but only cervical length in women with preterm labor, changed significantly throughout the period of 24-34 weeks' gestation (P < 0.01). The cervix was significantly longer in parous women and in women with a body mass index of more than 26 kg/m2, but was shorter in women of advanced gestational age. The cervix was significantly wider in parous women and in those of advanced gestational age. Weekly crude rate, adjusted for parity and prepregnancy body mass index, of both cervical length shortening and cervical width widening was 0.4 mm in women with term labor. Women with preterm labor had cervical shortening of 0.5 mm per week. CONCLUSIONS: Gestational age, parity and prepregnancy body mass index are significantly associated with the dynamic changes of cervical length and width in Thai women. These factors should be considered when assessing normal values of cervical dimensions and for predicting the risk of preterm delivery.     

Cervical length in the early second trimester for detection of triplet pregnancies at risk for preterm birth.

OBJECTIVE: Preterm triplet delivery is common and has a tremendous impact on neonatal mortality and morbidity. We aimed at assessing early second-trimester cervical length as a means of detecting triplet pregnancies at risk for preterm birth. METHODS: Cervical length was measured in triplet pregnancies during weeks 14 to 20. Cervical length of less than 25 mm was used as a cutoff to divide individuals into 2 groups. Perinatal outcome parameters were compared between the 2 groups and included gestational age at delivery, birth weights, and neonatal intensive care unit admission rates. Sensitivity, specificity, and positive and negative predictive values were calculated for cervical length as a screening method for preterm birth. RESULTS: We evaluated 36 triplets during weeks 14 to 20. Cervical length of less than 25 mm was measured in 14 (group I), 12 of which were delivered before 32 weeks (mean +/- SD, 28.4 +/- 3.1 weeks). Four of 22 women with cervical length of greater than 25 mm (group II) had delivery before 32 weeks (mean, 30.1 +/- 1.8 weeks). The mean gestational age at delivery for all parturients from group II was 33.1 +/- 2.1 weeks (P < .05). Group I neonates had lower birth weights (972 versus 1889 g; P < .001) and higher rates of low 5-minute Apgar scores and neonatal intensive care unit admissions compared with group II neonates. The sensitivity of a shorter cervix as a predictor of preterm labor was 75%, with specificity of 90%, a positive predictive value of 83%, and a negative predictive value of 81%. CONCLUSIONS: Cervical length of less than 25 mm at 14 to 20 weeks' gestation is associated with preterm delivery and adverse perinatal outcome in triplet pregnancies.     

The use of a variable cut-off value of cervical length in women admitted for preterm labor before and after 32 weeks.

OBJECTIVE: To determine whether the optimal cut-off value to predict low risk of preterm delivery in women admitted for preterm labor should be adjusted for gestational age. METHODS: A cohort of 333 women with singleton pregnancies admitted with preterm labor and intact membranes between 24 and < 36 weeks' gestation was studied. The women were categorized according to prematurity into one of two groups: those admitted at < 32 weeks (Group 1, very preterm) and those admitted at >or= 32 weeks (Group 2, preterm). Transvaginal ultrasound was performed 24-48 h after admission and cervical length measured. The predictive value of different cut-off points was explored. Outcome variables were spontaneous preterm delivery within 7 days of admission and delivery at < 34 weeks. RESULTS: The mean ( +/- SD) gestational ages at admission and delivery were 31.9 ( +/- 2.6) and 37.5 ( +/- 2.2) weeks, respectively, and the mean ( +/- SD) cervical length was 30.4 ( +/- 8.9) mm. The rates of spontaneous delivery within 7 days and at < 34 weeks were 6.3 and 7.0%, respectively. The cut-off value of 15-mm cervical length showed a sensitivity, negative predictive value and false positive rate for delivery within 7 days of 0, 96.5 and 2.7% in the very preterm group, and 35.3, 94.6 and 4% in the preterm group, respectively. For a cut-off point of 25 mm, these values were 75, 99 and 14.3%, and 70.6, 96.8 and 24.5%. CONCLUSIONS: The predictive value of different cut-off points of cervical length is similar at different gestational ages. However, the higher false positive rate after 32 weeks' gestation might justify the adoption of gestational-age related cut-off values in clinical protocols. In women admitted at < 32 weeks' gestation, a cut-off point of 25 mm may be used to predict a low risk of preterm delivery, whereas in women admitted at 32 weeks or later, 15 mm might be more appropriate. Published by John Wiley & Sons, Ltd.     

Cervical length at 23 weeks in triplets: prediction of spontaneous preterm delivery.

OBJECTIVES: To establish the distribution of cervical length at 23 weeks of gestation in triplet pregnancies and to examine the relation to preterm delivery before 33 weeks. METHODS: Cervical length was measured by transvaginal sonography at 23 (range 22-24) weeks of gestation in 43 triplet pregnancies. The distribution of cervical length was determined and the relationship between cervical length and the rate of spontaneous preterm delivery before 33 weeks was calculated. RESULTS: The cervical length distribution was skewed to the left with a median of 34 mm. The rate of spontaneous labor and delivery before 33 weeks increased exponentially with decreasing cervical length at 23 weeks from 8% at 36-48 mm, to 11% at 26-35 mm, 33% at 16-25 mm and 67% at 15 mm or less. Cervical length was < or = 30 mm, < or = 25 mm and < or = 15 mm in 37%, 16% and 8% of cases, respectively, and the corresponding sensitivities in the prediction of spontaneous delivery before 33 weeks were 67%, 50% and 33%. CONCLUSIONS: In triplet pregnancies, measurement of cervical length provides a useful prediction of risk for spontaneous early preterm delivery.     

Cervical changes in twin pregnancies observed by transvaginal ultrasound during the latter half of pregnancy: a longitudinal, observational study.

OBJECTIVE: To determine what constitutes normal cervical changes in twin gestations during the latter half of pregnancy, and whether there are differences in the pattern of cervical change between women expecting twins giving birth at term (> or = 36 completed gestational weeks, GW) and preterm. METHODS: Twenty women (12 nulliparous, eight parous) expecting twins were examined with transvaginal ultrasound every week from 24 GW until delivery. Cervical length and width were measured, the inner cervical os was assessed as being closed or open, and any dynamic cervical changes were noted. Examination results were unavailable to the staff involved in the care of the women. RESULTS: Eight women (40%) delivered preterm spontaneously at 32-35 GW. Cervical length remained unchanged ( approximately 10 mm) in one woman, who delivered preterm. It decreased in the remaining 19 women. The median shortening rate for women manifesting a continuous shortening of the cervix was 2.9 (0.8-5.2) mm/week in women giving birth preterm vs. 1.8 (0.8-2.4) mm/week in those who gave birth at term (P = 0.08). Median cervical length at the first examination was similar in women who delivered preterm and at term (39 vs. 41 mm), but at 32 GW the cervix was shorter in women who delivered preterm (median, 18 vs. 31 mm, P = 0.02). Cervical width remained unchanged in 63% (5/8) of the women who delivered preterm vs. 8% (1/12) of those who gave birth at term (P = 0.02). The cervix became wider in the remaining women. Median cervical width at the first examination was similar in women who delivered preterm and at term (38 vs. 38 mm), but in women who delivered preterm the cervix was thinner at 0-6 days before spontaneous start of labor (median, 40 vs. 48 mm, P = 0.07). An opening of the inner cervical os was seen < or = 27 GW in 88% (7/8) of the women who delivered preterm vs. 17% (2/12) of those who delivered at term (P = 0.006), the corresponding figures for dynamic changes being 63% (5/8) vs. 17% (2/12) (P = 0.06). Dynamic changes were seen in a greater proportion of the examinations in women who delivered preterm (median, 25% vs. 4%, P = 0.07). CONCLUSIONS: The pattern of cervical changes from 24 GW to delivery differs between twin pregnancies delivering preterm (at 32-35 GW) and at term (> or = 36 GW). In twin pregnancies delivered preterm cervical shortening is more rapid, the cervix does not broaden to the same extent as in twins delivered at term, an open inner cervical os and dynamic cervical changes are seen earlier in gestation, and dynamic cervical changes are seen more often. Cervical changes in women with twins who give birth as early as at 24-31 GW may be different.     

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.     

How to identify twins at low risk of spontaneous preterm delivery.

OBJECTIVE: The aim of this study was to evaluate transvaginal sonographic assessment of cervical length at 23 weeks as a screening test for spontaneous preterm delivery in order to define a cut-off value that could be used to select twin pregnancies at low risk of spontaneous preterm delivery. METHODS: In a prospective multicenter study of 383 twin pregnancies included before 14 + 6 weeks a cervical scan with measurement of the cervical length was performed at 23 weeks' gestation. The results were blinded for the clinicians if the cervical length was > or = 15 mm. The rates of spontaneous delivery at different cut-off levels of cervical length were determined. RESULTS: Eighty-nine percent of the twins had dichorionic placentation and 58% were conceived after assisted reproduction. The rate of spontaneous preterm delivery was 2.3% (1.5% for dichorionic (DC) and 9.1% for (MC) monochorionic twins) before 28 weeks and 18.5% (17.1% for DC and 29.5% for MC twins) before 35 weeks. The screen-positive rate was 5% for a cervical length < or = 20, 7-8% at < or = 25, 16-17% at < or = 30 and 34-48% at < or = 35 mm depending on chorionicity. The false-negative rate (1 - negative predictive value) ranged from 1.2% at 28 weeks to 18.6% at 35 weeks for all twins. Receiver-operating characteristics curves showed that the sensitivity increased with declining gestational age with cut-off levels of highest accuracy at 21 mm for 28 weeks and 29 mm for 33 weeks. CONCLUSIONS: Cervical length measurement at 23 weeks of gestation is a good screening test for predicting twins at low risk of preterm and very preterm delivery, especially in DC twins. The present results suggest that a cut-off of 25 mm should be recommended.     

Vaginal progesterone is associated with a decrease in risk for early preterm birth and improved neonatal outcome in women with a short cervix: a secondary analysis from a randomized, double-blind, placebo-controlled trial.

OBJECTIVE: To investigate the efficacy of vaginal progesterone to prevent early preterm birth in women with sonographic evidence of a short cervical length in the midtrimester. METHODS: This was a planned, but modified, secondary analysis of our multinational, multicenter, randomized, placebo-controlled trial, in which women were randomized between 18 + 0 and 22 + 6 weeks of gestation to receive daily treatment with 90 mg of vaginal progesterone gel or placebo. Cervical length was measured with transvaginal ultrasound at enrollment and at 28 weeks of gestation. Treatment continued until either delivery, 37 weeks of gestation or development of preterm rupture of membranes. Maternal and neonatal outcomes were evaluated for the subset of all randomized women with cervical length < 28 mm at enrollment. The primary outcome was preterm birth at 相似文献   

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.     

Vaginal ultrasound and cervical cerclage: a prospective study.

Vaginal ultrasound is a new technique for the objective assessment of the pregnant cervix. Twenty patients (21 pregnancies) were scanned at regular intervals throughout pregnancy after cervical cerclage by the vaginal route. Patients were recruited in 2 consecutive years in each of two centers with a low incidence of cervical cerclage (less than 0.5% of all pregnancies). Cervical cerclage, using Mersilene tape inserted by anterior and posterior incisions, positioned the cervical suture in the middle third of the cervical canal in all procedures (21/21). Ultrasound features including dilatation of the internal cervical os and herniation of the gestational sac to the level of the cervical suture were detected in 4/21 pregnancies at 5-7 weeks prior to delivery (21-33 weeks). Six patients (6/21) delivered preterm (< 37 weeks) without ultrasound features associated with cervical incompetence. Eleven patients (11/21) had a closed internal cervical os throughout pregnancy that remained closed after removal of the cervical suture at 38 weeks. In this study ultrasound features associated with cervical incompetence had a sensitivity of 40% and a specificity of 100% in the prediction of preterm pregnancy loss in this group of patients undergoing cerclage. Vaginal ultrasound is a simple, non-invasive technique that permits the detection of ultrasound features associated with cervical incompetence during pregnancy in patients who have had prophylactic cervical cerclage at 14-16 weeks' gestation. Ultrasound features associated with cervical incompetence were rare in this group of patients (4/21 from an overall obstetric population of 8000 deliveries) indicating a prevalence of cervical incompetence in the range of 1 : 1000-1 : 2000 deliveries. In the majority of patients undergoing cerclage (11/21) the clinical diagnosis of 'cervical incompetence' was incorrect as shown by the detection of a normal cervical canal following removal of the suture at 38 weeks.     

Transvaginal sonographic examination of the cervix in asymptomatic pregnant women: review of the literature.

Different strategies have been developed to refine the prediction of the risk of preterm delivery in asymptomatic patients. Transvaginal sonography has been used for this reason to measure and examine the length and shape of the cervix. In this review, we focus on clinical studies involving transvaginal sonographic assessment of the cervix in asymptomatic women at high risk of preterm delivery and in the general pregnant population. Three ultrasound signs are suggestive of cervical incompetence, namely, dilatation of the internal os, sacculation or prolapse of the membranes into the cervix (with shortening of the functional cervical length) either spontaneously or induced by transfundal pressure, and short cervix in the absence of uterine contractions. Transvaginal sonography has clearly demonstrated that cerclage leads to a measurable increase in cervical length which may contribute to the success of this procedure in reducing the risk of preterm delivery. Several non-randomized interventional studies among patients with cervical incompetence have been published. They have defined a new group of patients requiring cerclage when the women show progressive cervical modifications on transvaginal sonography, while in other studies, cerclage performed on the basis of cervical changes on transvaginal sonography did not prevent premature delivery. One prospective randomized trial in asymptomatic high-risk women has shown two benefits of cerclage following indications for transvaginal sonography: (1) it would generate fewer prophylactic cerclages in high-risk women; (2) therapeutic cerclage before 27 weeks may reduce the incidence of premature delivery before 34 weeks. The risk of preterm delivery is inversely correlated with cervical length. Routine transvaginal sonography of the cervix performed between 18 and 22 weeks can help identify patients at risk of preterm delivery. However, given the low prevalence of preterm births, screening would generate either a high false-positive rate or a low sensitivity. One non-randomized interventional study among patients with a short cervix on routine ultrasound examination found a lower risk of delivery before 32 weeks in the cerclage group than in the expectant management group. However, to date, there have been no prospective randomized trials in a general population. Although evidence is still lacking, there does appear to be a benefit in performing a cerclage rather than continuing with expectant management in cases with sonographic appearance of cervical incompetence in asymptomatic women at high risk of preterm delivery. Ultrasound can be offered to reduce the indications of cerclage for cases in which the situation is uncertain. Within the general obstetric population, transvaginal sonography might help in the selection of asymptomatic but high-risk women. However, the benefit associated with cerclage for sonographic indication has not been demonstrated.     

Cervical length in women in preterm labor with intact membranes: relationship to intra-amniotic inflammation/microbial invasion, cervical inflammation and preterm delivery.

OBJECTIVE: Intra-amniotic infection, diagnosed by microbial invasion of the amniotic cavity (MIAC) and/or the presence of intra-amniotic inflammation (IAI), is related to adverse perinatal outcome in women with preterm labor. Due to the subclinical nature of IAI, a correct diagnosis depends on amniocentesis, which is an invasive method not performed as a clinical routine. The aim of this study was to evaluate if cervical length measured by transvaginal sonography could assist in the identification of women at high risk for IAI. METHODS: Cervical length was assessed by transvaginal sonography in 87 women with singleton pregnancies in preterm labor (<34 weeks of gestation). Cervical (n=87) and amniotic (n=55) fluids were collected. Polymerase chain reactions for Ureaplasma urealyticum and Mycoplasma hominis, and culture for aerobic and anaerobic bacteria, were performed. Interleukin (IL)-6 and IL-8 were analyzed by enzyme-linked immunosorbent assay. RESULTS: IAI was present in 25/55 (45%) of the patients presenting with preterm labor who underwent amniocentesis. Women with IAI had a significantly shorter cervical length (median, 10 (range, 0-34) mm) than had those without IAI (median, 21 (range, 11-43) mm) (P<0.0001). Receiver-operating characteristics curve analysis showed that a cervical length (cut-off of 15 mm) predicted IAI (relative risk, 3.6; CI, 1.9-10.0) with a sensitivity of 72%, specificity of 83%, positive predictive value of 78% and negative predictive value of 78%. Cervical length was also significantly associated with preterm birth up to 7 days from sampling and at 相似文献   

Dynamic cervical change: is real-time sonographic cervical shortening predictive of preterm delivery in patients with symptoms of preterm labor?

OBJECTIVES: To determine prospectively if dynamic cervical change (spontaneous real-time cervical shortening) is predictive of preterm delivery at < 37 weeks' gestation in patients with symptoms of preterm labor. METHODS: This was a prospective study of patients at 23-34 weeks' gestation who were symptomatic for preterm labor. Patients underwent a 10-min real-time sonographic cervical length assessment with measurements taken at 1-min intervals. The presence or absence of dynamic cervical change, defined as real-time changes in cervical length observable to the naked eye of the sonologist during the examination, was recorded. Gestational age at delivery was obtained from medical records. Preterm delivery was defined as delivery at < 37 weeks' gestation. Dynamic cervical change and initial and minimum cervical lengths were assessed for prediction of preterm delivery. RESULTS: Seventy-six patients were enrolled, and 66 were available for outcome analysis. Thirty-one patients (47%) exhibited dynamic cervical change. Patients with dynamic change had shorter initial cervical lengths (27 mm vs. 36 mm, P = 0.001), shorter minimum cervical lengths (20 vs. 33 mm, P < 0.001) and larger changes in cervical length during the examination period (10 vs. 4 mm, P < 0.001). In the subgroup of patients with an initial cervical length > 30 mm, those with dynamic change delivered earlier than did those without dynamic change (36.8 vs. 38.6 weeks, P = 0.02), and a higher percentage delivered preterm (27% vs. 11%, odds ratio (OR), 3.0 (0.5-17.0)). Multivariate analysis showed that minimum cervical length was a better predictor of preterm delivery than was initial cervical length. CONCLUSIONS: Dynamic cervical change occurs frequently in association with shortened cervical length. In patients with longer initial cervical lengths, dynamic change may increase the risk for preterm delivery. When dynamic change is noted in a patient with preterm labor symptoms, use of the minimum cervical length observed may be better compared with initial cervical length for determining preterm delivery risk.     

Cervical length, multifetal pregnancy reduction, and prediction of preterm birth

PURPOSE: To evaluate the application of transvaginal sonography assessment of cervical length before fetal reduction for predicting spontaneous preterm birth in triplet gestations reduced to twins. METHODS: This retrospective study was conducted at the ultrasound unit of a university-affiliated municipal hospital. The study cohort consisted of 25 women with triplet gestations following ovulation induction or assisted-reproduction techniques who underwent fetal reduction to twins. Cervical length was assessed via transvaginal sonography before fetal reduction, and data on pregnancy outcome were retrieved from maternal records and/or maternal interviews. RESULTS: Cervical length (mean +/- SD) at reduction was 4.0 +/- 0.85 (range: 1.2-5.5). Five women were excluded from statistical evaluation because pregnancy complications precluded spontaneous delivery. Two of 3 (67%) women with a cervical length of <3.5 cm delivered prior to 33 weeks' gestation compared with 1/17 (6%) women with a cervical length > or = 3.5 cm. This difference was statistically significant (P < 0.05). The sensitivity, specificity, positive predictive value, and negative predictive value of cervical lengths <3.5 cm to predict delivery prior to 33 gestational weeks was 67%, 94%, 67%, and 94%, respectively. CONCLUSIONS: Measurement of cervical length in triplet pregnancies before fetal reduction provides useful predictive information on the risk for preterm delivery.     

Sonographic cervical length in singleton pregnancies with intact membranes presenting with threatened preterm labor.

OBJECTIVE: Less than 10% of women presenting with preterm contractions progress to active labor and delivery. This study investigates whether cervical length measurements by ultrasound can discriminate between true and false labor in women presenting with threatened preterm labor. METHODS: Cervical length was measured by transvaginal ultrasound in 253 women with singleton pregnancies presenting with painful uterine contractions at a median age of 31 (range, 24-35) weeks of gestation. Women presenting in active labor, defined by the presence of cervical dilatation of >or = 3 cm, those with ruptured membranes and those that underwent prior or subsequent cervical cerclage were excluded from the study. The clinical management was determined by the attending obstetrician without taking into account the cervical length. Primary outcome of the study was delivery within 7 days of presentation based on the results of randomized studies on the use of tocolytics in women with preterm labor that reported a prolongation of pregnancy by 7 days. RESULTS: Delivery within 7 days of presentation occurred in 21/253 (8.3%) pregnancies and this was inversely related to cervical length. Receiver-operating characteristics (ROC) curves established a cervical length of 15 mm as the most relevant cut-off level for the prediction of preterm delivery within 7 days. In 217 cases the cervical length was > or = 15 mm and only four of these (1.8%) delivered within 7 days. In the 36 women with cervical length < 15 mm, delivery occurred in 17 (47.2%) within 7 days. Logistic regression analysis demonstrated that significant independent contribution in the prediction of delivery within 7 days was provided by cervical length, contraction frequency at presentation, previous history of preterm delivery and vaginal bleeding. There was no significant contribution from gestation at presentation, ethnic origin, maternal age, parity, cigarette smoking or the administration of tocolysis, antibiotics or steroids. Similar results were shown in a subanalysis of 162 patients presenting at a gestational age below 32 weeks: 9/19 patients (47.4%) with a cervical length below 15 mm delivered within 7 days compared to 3/143 (2.1%) with a cervical length > or = 15 mm. Univariate as well as multivariate analyses confirmed cervical length to be a significant independent predictor of delivery within 7 days in this population. CONCLUSIONS: Sonographic measurement of cervical length helps to avoid overdiagnosis of preterm labor in women with preterm contractions and intact membranes.