Reference
Reference
Study Type
Study Type
Patients/Events
Patients/Events
Study Objective(Purpose of Study)
Study Objective(Purpose of Study)
Study Results
Study Results
Study Quality
Study Quality
1. Goldenberg RL. The management of preterm labor. Obstet Gynecol. 2002;100(5 Pt 1):1020-1037. Review/Other-Dx N/A To review management of preterm labor. The most important components of management are aimed at preventing neonatal complications through the use of corticosteroids and antibiotics to prevent group B streptococcal neonatal sepsis, and avoiding traumatic deliveries 4
2. Hack M, Fanaroff AA. Outcomes of children of extremely low birthweight and gestational age in the 1990's. Early Hum Dev. 1999;53(3):193-218. Review/Other-Dx N/A To review survival of children of extremely low birthweight and gestational age in the 1990's. According to the authors, a review of the world literature and their experience reveal that at 23 weeks gestation survival ranges from 2% to 35%. At 24 weeks gestation the range is 17% to 58%, and at 25 weeks gestation 35% to 85%. Authors conclude that with current methods of care, the limits of viability have been reached. 4
3. Berghella V, Roman A, Daskalakis C, Ness A, Baxter JK. Gestational age at cervical length measurement and incidence of preterm birth. Obstet Gynecol. 2007;110(2 Pt 1):311-317. Review/Other-Dx 705 women To estimate the risk of spontaneous preterm birth based on transvaginal ultrasound cervical length and gestational age at which cervical length was measured. 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. 4
4. Hibbard JU, Tart M, Moawad AH. Cervical length at 16-22 weeks' gestation and risk for preterm delivery. Obstet Gynecol. 2000;96(6):972-978. Observational-Dx 760 gravidas 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. 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%. 3
5. Taipale P, Hiilesmaa V. Sonographic measurement of uterine cervix at 18-22 weeks' gestation and the risk of preterm delivery. Obstet Gynecol. 1998;92(6):902-907. Observational-Dx 3694 consecutive pregnant women with live singleton fetuses To examine the uterine cervix with ultrasonography to discover whether such a procedure would be helpful in determining which women will deliver prematurely. Spontaneous delivery occurred before 37 completed weeks in 88 women (2.4%) and before 35 weeks in 31 (0.8%). The relative risk of delivery before 35 weeks was 8 (95% confidence interval 3, 19) when the cervical length was 29 mm or shorter. When dilatation of the internal cervical os of 5 mm or greater was present, the relative risk of delivery before 35 weeks was 28 (95% confidence interval 12, 67). Either short cervix (29 mm or less) or dilatation of internal cervical os (5 mm or greater) was present in 3.6% of the population; this combination had a sensitivity of 29% in predicting delivery at earlier than 35 weeks. After adjusting for cervical dilatation and length by using multiple logistic regression, nulliparity also remained a risk factor for delivery before 35 weeks (odds ratio 3.6, 95% confidence interval 1.7, 7.5). 2
6. Iams JD, Goldenberg RL, Meis PJ, et al. The length of the cervix and the risk of spontaneous premature delivery. National Institute of Child Health and Human Development Maternal Fetal Medicine Unit Network. N Engl J Med. 1996;334(9):567-572. Observational-Dx 2,915 women Prospective, multicenter study to measure cervical length (using TVUS), and to document incidence of spontaneous delivery before 35 weeks. To calculate RR for preterm delivery based on cervical length. RR of preterm delivery increases as cervical length decreases. At 24 weeks gestation age (RR was: (also done at 28 weeks): Cervix length at or below 40 mm (75th percentile); RR=1.98. Cervix length at or below 35 mm (50th percentile); RR=2.35. Cervical length at or below 30 mm (25th percentile); RR=3.79. Cervical length at or below 26 mm (10th percentile); RR=6.19. Cervical length at or below 22 mm (5th percentile); RR=9.49. Cervical length at or below 13mm (1st percentile) RR=13.99. 3
7. Hassan SS, Romero R, Berry SM, et al. Patients with an ultrasonographic cervical length < or =15 mm have nearly a 50% risk of early spontaneous preterm delivery. Am J Obstet Gynecol. 2000;182(6):1458-1467. Observational-Dx 6877 patients To determine the value in the prediction of spontaneous preterm delivery of ultrasonographically measured cervical length measured between 14 and 24 weeks' gestation. Mean cervical length was 37.5 mm. Odds ratios for early preterm delivery (< or =32 weeks' gestation) for patients with cervical lengths < or =10, < or =15, < or = 20, < or =25, and < or =30 mm were, respectively, 29.3 (95% confidence interval, 11.3-75.8), 24.3 (95% confidence interval, 12. 9-45.9), 18.3 (95% confidence interval, 10.8-31.0), 13.4 (95% confidence interval, 8.8-20.6), and 3.2 (95% confidence interval, 2. 4-4.4). For early preterm delivery a cervical length of < or =15 mm had a positive predictive value of 47.6%, a negative predictive value of 96.7%, a sensitivity of 8.2%, and a specificity of 99.7%. 3
8. Guzman ER, Walters C, Ananth CV, et al. A comparison of sonographic cervical parameters in predicting spontaneous preterm birth in high-risk singleton gestations. Ultrasound Obstet Gynecol. 2001;18(3):204-210. Observational-Dx 469 high-risk gestations 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. 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. 3
9. To MS, Skentou C, Liao AW, Cacho A, Nicolaides KH. Cervical length and funneling at 23 weeks of gestation in the prediction of spontaneous early preterm delivery. Ultrasound Obstet Gynecol. 2001;18(3):200-203. Observational-Dx 6334 pregnancies 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. Women with a short cervix (=15 mm) are given the option of participating in an ongoing multicenter randomized trial of cervical cerclage. The median cervical length was 36 mm and in 1.6% of cases the length was =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 =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 (OR for short cervix = 24.9, Z = 4.43, P<0.0001; OR for funneling = 1.8, Z = 0.84, P=0.40). In the prediction of preterm delivery, funneling does not provide any significant contribution in addition to cervical length. 3
10. Crane JM, Hutchens D. Transvaginal sonographic measurement of cervical length to predict preterm birth in asymptomatic women at increased risk: a systematic review. Ultrasound Obstet Gynecol. 2008;31(5):579-587. Review/Other-Dx 14 articles , 2258 women To estimate the ability of cervical length measured by transvaginal ultrasonography in asymptomatic high-risk women to predict spontaneous preterm birth. Cervical length measured by transvaginal ultrasonography predicted spontaneous preterm birth. The shorter the cervical length cut-off the higher the positive likelihood ratio (LR). The most common cervical length cut-off was < 25 mm. Using this cut-off to predict spontaneous preterm birth at < 35 weeks, transvaginal ultrasonography at < 20 weeks' gestation revealed LR+ = 4.31 (95% CI, 3.08-6.01); at 20-24 weeks, LR+ = 2.78 (95% CI, 2.22-3.49); and at > 24 weeks, LR+ = 4.01 (95% CI, 2.53-6.34). In women with a history of spontaneous preterm birth (six studies involving 663 women) cervical length at < 20 weeks revealed LR+ = 11.30 (95% CI, 3.59-35.57) and at 20-24 weeks LR+ = 2.86 (95% CI, 2.12-3.87), but there were limited data on the use of cervical length of more than 24 weeks in this group (one study involving 42 women). In women who had had excisional cervical procedures, two studies presented data on cervical length (one at < 24 weeks and one at > 24 weeks), finding cervical length at < 24 weeks to be predictive of spontaneous preterm birth at < 35 weeks (LR+ = 2.91, 95% CI, 1.69-5.01). One study (of 64 women) evaluated cervical length in women with uterine anomalies, finding it predictive of spontaneous preterm birth at < 35 weeks (LR+ = 8.14, 95% CI, 3.12-21.25). 4
11. Berghella V, Baxter JK, Hendrix NW. Cervical assessment by ultrasound for preventing preterm delivery. [Review][Update of Cochrane Database Syst Rev. 2009;(3):CD007235; PMID: 19588421]. Cochrane Database Syst Rev. (1)CD007235, 2013 Jan 31. Review/Other-Dx 5 trials (n = 507) To assess the effectiveness of antenatal management based on transvaginal ultrasound of cervical length (TVU CL) screening for preventing PTB. Knowledge of TVU CL results was associated with a non-significant decrease in PTB at less than 37 weeks (22.3% versus 34.7%, respectively; average risk ratio 0.59, 95% confidence interval (CI) 0.26 to 1.32; two trials, 242 women) and at less than 34 weeks (6.9% verus 12.6%; RR 0.55, 95% CI 0.25 to 1.20; three trials, 256 women). Delivery occurred at a later gestational age in the knowledge versus no knowledge groups (mean difference (MD) 0.64 weeks, 95% CI 0.03 to 1.25; three trials, 290 women). For all other outcomes for which there were available data (PTB at less than 34 or 28 weeks; birthweight less than 2500 grams; perinatal death; maternal hospitalization; tocolysis; and steroids for fetal lung maturity), there was no evidence of a difference between groups.The trial of singleton gestations with PPROM (n = 92) evaluated as its primary outcome safety of TVU CL in this population, and not its effect on management. There was no evidence of a difference in incidence of maternal and neonatal infections between the TVU CL and no TVU CL groups.In the trial of twin gestations with or without PTL (n = 125), there was no evidence of a difference in PTB at less than 36, 34, or 30 weeks, gestational age at delivery, and other perinatal and maternal outcomes between the TVU CL and the no TVU CL groups. Life-table analysis revealed significantly less PTB at less than 35 weeks in the TVU CL group compared with the no TVU CL group (P = 0.02). 4
12. Fonseca EB, Celik E, Parra M, Singh M, Nicolaides KH. Progesterone and the risk of preterm birth among women with a short cervix. N Engl J Med. 2007;357(5):462-469. Experimental-Dx 250 women Multicenter, randomized trial was designed to evaluate the effect of vaginal progesterone on the incidence of spontaneous early preterm delivery in asymptomatic women found at routine mid-trimester screening to have a short cervix. Spontaneous delivery before 34 weeks of gestation was less frequent in the progesterone group than in the placebo group (19.2% vs. 34.4%; relative risk, 0.56; 95% confidence interval [CI], 0.36 to 0.86). Progesterone was associated with a nonsignificant reduction in neonatal morbidity (8.1% vs. 13.8%; relative risk, 0.59; 95% CI, 0.26 to 1.25; P=0.17). There were no serious adverse events associated with the use of progesterone. 1
13. Hassan SS, Romero R, Vidyadhari D, et al. Vaginal progesterone reduces the rate of preterm birth in women with a sonographic short cervix: a multicenter, randomized, double-blind, placebo-controlled trial. Ultrasound Obstet Gynecol. 2011;38(1):18-31. Experimental-Dx 458 women Multicenter, randomized, double-blind, placebo-controlled trial to determine the efficacy and safety of using micronized vaginal progesterone gel to reduce the risk of preterm birth and associated neonatal complications in women with a sonographic short cervix. Women allocated to receive vaginal progesterone had a lower rate of preterm birth before 33 weeks than did those allocated to placebo (8.9% (n=21) vs 16.1% (n=36); relative risk (RR), 0.55; 95% CI, 0.33-0.92; P=0.02). The effect remained significant after adjustment for covariables (adjusted RR, 0.52; 95% CI, 0.31-0.91; P=0.02). Vaginal progesterone was also associated with a significant reduction in the rate of preterm birth before 28 weeks (5.1% vs 10.3%; RR, 0.50; 95% CI, 0.25-0.97; P=0.04) and 35 weeks (14.5% vs 23.3%; RR, 0.62; 95% CI, 0.42-0.92; P=0.02), respiratory distress syndrome (3.0% vs 7.6%; RR, 0.39; 95% CI, 0.17-0.92; P=0.03), any neonatal morbidity or mortality event (7.7% vs 13.5%; RR, 0.57; 95% CI, 0.33-0.99; P=0.04) and birth weight < 1500 g (6.4% (15/234) vs 13.6% (30/220); RR, 0.47; 95% CI, 0.26-0.85; P=0.01). There were no differences in the incidence of treatment-related adverse events between the groups. 1
14. Cahill AG, Odibo AO, Caughey AB, et al. Universal cervical length screening and treatment with vaginal progesterone to prevent preterm birth: a decision and economic analysis. Am J Obstet Gynecol. 2010;202(6):548 e541-548. Review/Other-Dx hypothetical cohort of 4 million pregnant patients To estimate which strategy is the most cost-effective for the prevention of preterm birth and associated morbidity. Universal sonographic screening for cervical length and treatment with vaginal progesterone was the most cost-effective strategy and was the dominant choice over the 3 alternatives: cervical length screening for women at increased risk for preterm birth and treatment with vaginal progesterone; risk-based treatment with 17 alpha-hydroxyprogesterone caproate (17-OHP-C) without screening; no screening or treatment. Universal screening represented savings of $1339 ($8325 vs $9664), when compared with treatment with 17-OHP-C, and led to a reduction of 95,920 preterm births annually in the United States. 4
15. Romero R, Nicolaides K, Conde-Agudelo A, et al. Vaginal progesterone in women with an asymptomatic sonographic short cervix in the midtrimester decreases preterm delivery and neonatal morbidity: a systematic review and metaanalysis of individual patient data. Am J Obstet Gynecol. 2012;206(2):124 e121-119. Meta-analysis 5 trials ; 775 women and 827 infants To determine whether the use of vaginal progesterone in asymptomatic women with a sonographic short cervix (</= 25 mm) in the midtrimester reduces the risk of preterm birth and improves neonatal morbidity and mortality. Treatment with vaginal progesterone was associated with a significant reduction in the rate of preterm birth <33 weeks (relative risk [RR], 0.58; 95% confidence interval [CI], 0.42-0.80), <35 weeks (RR, 0.69; 95% CI, 0.55-0.88), and <28 weeks (RR, 0.50; 95% CI, 0.30-0.81); respiratory distress syndrome (RR, 0.48; 95% CI, 0.30-0.76); composite neonatal morbidity and mortality (RR, 0.57; 95% CI, 0.40-0.81); birthweight <1500 g (RR, 0.55; 95% CI, 0.38-0.80); admission to neonatal intensive care unit (RR, 0.75; 95% CI, 0.59-0.94); and requirement for mechanical ventilation (RR, 0.66; 95% CI, 0.44-0.98). There were no significant differences between the vaginal progesterone and placebo groups in the rate of adverse maternal events or congenital anomalies. M
16. Werner EF, Han CS, Pettker CM, et al. Universal cervical-length screening to prevent preterm birth: a cost-effectiveness analysis. Ultrasound Obstet Gynecol. 2011;38(1):32-37. Review/Other-Dx cohort of 100,000 women Decision analysis model to determine whether routine measurement of second-trimester transvaginal cervical length by ultrasound in low-risk singleton pregnancies is a cost-effective strategy. The model predicts that routine cervical-length screening is a dominant strategy when compared to routine care. For every 100,000 women screened, $12,119,947 can be potentially saved (in 2010 US dollars) and 423.9 quality-adjusted life-years could be gained. Additionally, the authors estimate that 22 cases of neonatal death or long-term neurologic deficits could be prevented per 100,000 women screened. Screening remained cost-effective but was no longer the dominant strategy when cervical-length ultrasound measurement costs exceeded $187 or when vaginal progesterone reduced delivery risk at < 34 weeks by less than 20%. 4
17. Committee on Practice Bulletins-Obstetrics, The American College of Obstetricians Gynecologists. Practice bulletin no. 130: prediction and prevention of preterm birth. Obstet Gynecol 2012;120:964-73. Review/Other-Dx N/A Practice guideline on prediction and prevention of preterm birth. N/A 4
18. Berghella V, Odibo AO, To MS, Rust OA, Althuisius SM. Cerclage for short cervix on ultrasonography: meta-analysis of trials using individual patient-level data. Obstet Gynecol. 2005;106(1):181-189. Meta-analysis 4 trials To estimate by meta-analysis of randomized trials whether cerclage prevents preterm birth in women with a short cervical length. In the total population, preterm birth at less than 35 weeks of gestation occurred in 29.2% (89/305) of the cerclage group, compared with 34.8% (105/302) of the no-cerclage groups (relative risk [RR] 0.84, 95% confidence interval [CI] 0.67-1.06). There was no significant heterogeneity in the overall analysis (P = .29). There was a significant reduction in preterm birth at less than 35 weeks in the cerclage group compared with the no-cerclage groups in singleton gestations (RR 0.74, 95% CI 0.57-0.96), singleton gestations with prior preterm birth (RR 0.61, 95% CI 0.40-0.92), and singleton gestations with prior second-trimester loss (RR 0.57, 95% CI 0.33-0.99). There was a significant increase in preterm birth at less than 35 weeks in twin gestations (RR 2.15, 95% CI 1.15-4.01). M
19. Goya M, Pratcorona L, Merced C, et al. Cervical pessary in pregnant women with a short cervix (PECEP): an open-label randomised controlled trial. Lancet. 2012;379(9828):1800-1806. Experimental-Tx 385 pregnant women Randomised, controlled trial to investigate whether the insertion of a cervical pessary in women with a short cervix identified by use of routine transvaginal scanning at 20-23 weeks of gestation reduces the rate of early preterm delivery. 385 pregnant women with a short cervix were assigned to the pessary (n=192) and expectant management groups (n=193), and 190 were analysed in each group. Spontaneous delivery before 34 weeks of gestation was significantly less frequent in the pessary group than in the expectant management group (12 [6%] vs 51 [27%], odds ratio 0.18, 95% CI 0.08-0.37; p<0.0001). No serious adverse effects associated with the use of a cervical pessary were reported. 1
20. Carlan SJ, Richmond LB, O'Brien WF. Randomized trial of endovaginal ultrasound in preterm premature rupture of membranes. Obstet Gynecol. 1997;89(3):458-461. Experimental-Dx 47 patients assigned to no-probe and 45 patients assigned to probe group Randomized study to assess the effect of weekly endovaginal US on the incidence of maternal infection and the time from rupture to delivery in women with preterm premature rupture of membranes. The latency period, defined as days from rupture to delivery, was 9.8 and 11.7 days for the no-probe and probe groups, respectively (95% CI, -5.9, 2.1). There were no significant differences in the incidence of chorioamnionitis (28% and 20%), endometritis (6% and 9%), or neonatal infection (17% and 20%). The mean latency period in women who went into spontaneous labor and whose initial cervical length was 3.0 cm or less was 9.4 days, compared with 11.0 days if the cervix exceeded 3.0 cm, a nonsignificant difference. There were three neonatal deaths, all in the probe group and none directly related to infection. Endovaginal US in patients whose pregnancies are complicated by preterm premature rupture of membranes does not appear to increase the incidence of maternal infection. 1
21. Jenkins SM, Kurtzman JT, Osann K. Dynamic cervical change: is real-time sonographic cervical shortening predictive of preterm delivery in patients with symptoms of preterm labor? Ultrasound Obstet Gynecol. 2006;27(4):373-376. Observational-Dx 76 patients enrolled and 66 available for outcome analysis Prospective study of patients at 23-34 weeks to determine 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. 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. 3
22. The Fetal Medicine Foundation. Online Education: Cervical assessment. 2014; Available at: http://www.fetalmedicine.com/fmf/online-education/05-cervical-assessment/. Accessed March 17, 2014. Review/Other-Dx N/A An online course on cervical assessment. The course explains the technique of measuring cervical length and the clinical applications of this measurement. N/A 4
23. Mella MT, Berghella V. Prediction of preterm birth: cervical sonography. Semin Perinatol. 2009;33(5):317-324. Review/Other-Dx N/A To review the evidence for cervical sonography as a screening test for the prediction of preterm birth. Cervical length (CL) measurement by TVU in the second trimester is one of the most effective screening methods for the prediction of preterm birth. The shortest best cervical length (CL) is the most effective measurement for clinical use. 4
24. de Tejada BM, Faltin DL, Kinkel K, Guittier MJ, Boulvain M, Irion O. Magnetic resonance imaging of the cervix in women at high risk for preterm delivery. J Matern Fetal Neonatal Med. 2011;24(11):1392-1397. Observational-Dx 100 women To assess whether changes in signal intensity of cervical stroma layers on MRI are associated with spontaneous preterm delivery. 36 women had a spontaneous preterm delivery. The proportion of spontaneous preterm delivery for high, intermediate, and low stromal differentiation was 7/24 (29%), 21/64 (33%; RR 1.1; 95% CI: 0.6–2.3), and 8/12 (67%; RR 2.3; 95% CI: 1.1–4.8), respectively. The risk of delivering within 7 days increased when stromal differentiation decreased, although the difference was not statistically significant. 2
25. Rovas L, Sladkevicius P, Strobel E, Valentin L. Reference data representative of normal findings at two-dimensional and three-dimensional gray-scale ultrasound examination of the cervix from 17 to 41 weeks' gestation. Ultrasound Obstet Gynecol. 2006;27(4):392-402. Observational-Dx 419 nulliparous women and 360 parous women To create reference values representative of normal findings on 2D and 3D TVU examination of the cervix from 17 to 41 weeks' gestation and to determine the agreement between cervical measurements taken by 2D and 3D TVU. There was excellent agreement between measurements taken by 2D and 3D US (interclass correlation coefficient values, 0.80–0.98) but measurements of cervical length taken using 3D US were greater than measurements taken by 2D US (mean difference, -0.04 +/- 0.36 cm). Cervical length did not change substantially between 17 and 32 gestational weeks but decreased progressively thereafter. Cervical length was similar in nulliparous and parous women at 17–32 weeks, but from 33 weeks the cervix tended to be longer in parous women. In nulliparae, cervical length decreased from a median of 3.8 (range, 0.7–6.1) cm at 17–32 weeks to 2.3 (range, 0.4–6.0) cm at 33–40 weeks and to 0.7 (range, 0.2–1.5) cm at 41 weeks. In parous women, the corresponding figures were 3.9 (range, 1.0–6.1) cm, 3.0 (range, 0.4–5.7) cm and 0.8 (range, 0.4–3.4) cm (results obtained by 3D US). Cervical anteroposterior diameter and width did not differ between nulliparous and parous women. Median anteroposterior diameter increased from 3.0 (range, 2.0–4.6) cm at 17–30 weeks to 3.5 (range, 1.8–5.5) cm at 31–40 weeks and to 4.0 (range, 2.8–5.9) cm at 41 weeks. Cervical width was 3.7 (range, 2.3–6.0) cm at 17–30 weeks and 4.5 (range, 2.3–6.1) cm at 31–41 weeks. The percentage of women with funneling increased from 4% (3/84) at 17–18 weeks to 63% (12/19) at 41 weeks and the percentage of women with an open cervical canal increased from 19% (15/84) to 72% (13/19). Funneling and opening of the cervical canal were equally common in nulliparous and parous women. 3
26. Feltovich H, Hall TJ, Berghella V. Beyond cervical length: emerging technologies for assessing the pregnant cervix. Am J Obstet Gynecol. 2012;207(5):345-354. Review/Other-Dx N/A Review emeerging technologies for asessing the pregnant cervix. Promising techniques to evaluate tissue hydration, collagen structure, and/or tissue elasticity are emerging. These will add to the body of knowledge about the cervix and facilitate the coordination of molecular studies and ultimately lead to novel approaches to preterm birth prediction and, finally, prevention. 4
27. Schnettler W, March M, Hacker MR, Modest AM, Rodriguez D. Impaired ultrasonographic cervical assessment after voiding: a randomized controlled trial. Obstet Gynecol. 121(4):798-804, 2013 Apr. Experimental-Dx 221 women To estimate whether the timing of bladder emptying affects focal myometrial contraction development and image adequacy. Two hundred twenty-one women provided 335 randomized encounters for analysis. Women in the deferred scan group were 30% less likely to experience a focal myometrial contraction (28.1% compared with 40.5%, RR 0.70, 95% CI 0.52-0.93) and 41% less likely to have inadequate images (18.6% compared with 31.5%, RR 0.59, 95% CI 0.40-0.86). The two groups were equally likely to be diagnosed with placenta previa (P=.13). However, participants in the deferred scan group were 76% less likely to have images demonstrating a placenta previa and focal myometrial contraction (3.0% compared with 12.5%, RR 0.24, 95% CI 0.09-0.62) than participants in the immediate scan group. Eight women would need to defer imaging for 15 minutes from bladder voiding to prevent one focal myometrial contraction of the lower uterine segment or inadequate imaging. 1
28. Guzman ER, Rosenberg JC, Houlihan C, Ivan J, Waldron R, Knuppel R. A new method using vaginal ultrasound and transfundal pressure to evaluate the asymptomatic incompetent cervix. Obstet Gynecol. 1994;83(2):248-252. Review/Other-Dx 150 pregnant patients without pregnancy loss, 31 asymptomatic pregnant patients To determine if transfundal pressure applied while scanning the cervix may assist in detecting asymptomatic incompetent cervix. Technique consisted of applying transfundal pressure for approximately 15 seconds in the direction of the uterine axis. The control patients were scanned a single time between 16 and 24 weeks gestational age. The at-risk patients were studied 73 times between 8 and 25 weeks gestational age. Transfundal pressure elicited no change in internal os in 150 control patients. Transfundal pressure elicited opening of the internal os or descent of the fetal membranes in 14/31 (45%) patients who were at risk. 4
29. Wong G, Levine D, Ludmir J. Maternal postural challenge as a functional test for cervical incompetence. J Ultrasound Med. 1997;16(3):169-175. Observational-Dx 24 pregnant patients without pregnancy loss, 41 patients at high-risk due to incompetent cervix To evaluate whether a postural challenge (consisting of an upright maternal position) can be used to detect early changes in patients with incompetent cervix. Technique consisted of examining the cervix by TVUS with the patient supine for at least 15 minutes, and then reexamining the cervix after she had been standing for at least 15 minutes. The control patients were scanned a single time; the at-risk patients were studied 74 times. In all cases gestation age ranged from 17-33 weeks. In 24 control patients, maternal postural challenge test elicited no change in cervical length. Each of these patients delivered at term. Of 41 at risk patients, maternal postural challenge test demonstrated a greater than 33% decrease in cervical length in 16 patients (14 of whom delivered prematurely). Only 1/25 at risk patients who had a decrease of less than 33% delivered prematurely. The sensitivity of a postural change in patients at risk for preterm delivery was 93.3%, and the specificity was 92.3%. 3
30. Guzman ER, Pisatowski DM, Vintzileos AM, Benito CW, Hanley ML, Ananth CV. A comparison of ultrasonographically detected cervical changes in response to transfundal pressure, coughing, and standing in predicting cervical incompetence. Am J Obstet Gynecol. 1997;177(3):660-665. Observational-Dx 89 patients To compare various noninvasive stress techniques for their ability to elicit ultrasonographic cervical changes and to determine their efficacy in detecting ultrasonographic cervical incompetence. The efficacy of transfundal pressure in detecting the cervix that had subsequent progressive changes on US was as follows: sensitivity 83.3%, specificity 97.2%, and PPV and NPV 88.2% and 95.8%, respectively. The efficacy of coughing was sensitivity 16.7%, specificity 100%, and PPV and NPV 100% and 85.5%, respectively. The efficacy of standing was sensitivity 33.3%, specificity 97.2%, and PPV and NPV 75% and 85.2%, respectively. Similar results were obtained when the analysis was confined to 37 patients who had a prior history of a mid-trimester miscarriage. Transfundal pressure was the most effective technique in eliciting cervical changes during the active assessment of the cervix during pregnancy and the most sensitive in detecting the cervix that had progressive second-trimester cervical shortening during pregnancy, compared with coughing or standing position. 3
31. Cicero S, Skentou C, Souka A, To MS, Nicolaides KH. Cervical length at 22-24 weeks of gestation: comparison of transvaginal and transperineal-translabial ultrasonography. Ultrasound Obstet Gynecol. 2001; 17(4):335-340. Observational-Dx 500 patients To investigate the feasibility of measuring cervical length by transperineal or translabial sonography and compare the measurements obtained by this approach with those obtained transvaginally. Cervical length was successfully measured transvaginally in all cases. In the first phase of the study cervical length was measured by translabial-transperineal sonography in 84% of the 200 patients but there was poor agreement with measurements obtained transvaginally and the 95% tolerance interval for paired observations was -11.0 mm to 16.1 mm. After audit of results it became apparent that the translabially-transperineally derived images were inadequate in more than half of the cases but in those with adequate paired measurements there was a very good agreement between the two and the 95% tolerance interval for paired observations was -5.8 mm to 5.2 mm. In the second phase of the study special attention was paid towards recording measurements of cervical length only in cases where both the internal and external os were adequately visualized. Successful measurements by translabial-transperineal sonography were obtained in 78% of cases and the 95% tolerance interval for paired observations was -5.8 mm to 6.1 mm. The degree of patient acceptability of the two methods was similar. 3
32. Hertzberg BS, Livingston E, DeLong DM, McNally PJ, Fazekas CK, Kliewer MA. Ultrasonographic evaluation of the cervix: transperineal versus endovaginal imaging. J Ultrasound Med. 2001;20(10):1071-1078; quiz 1080. Observational-Dx 64 pregnant women To compare transperineal and endovaginal ultrasonography of the gravid cervix to evaluate image quality and assess for a systematic difference in cervical lengths measured by the 2 techniques. There was a strong reviewer preference for endovaginal ultrasonographic images over transperineal images for both assessing the cervix (P< .001) and evaluating for placenta previa (P< .001). Despite this, transperineal and endovaginal ultrasonographic images were frequently rated as similar in diagnostic quality by both reviewers for depicting the cervix (35.9% of patients) and evaluating for placenta previa (57.8% of patients). The mean length of the cervix was slightly shorter at transperineal ultrasonography (28.4 mm) than at endovaginal ultrasonography (30.1 mm). When cervical lengths were subdivided by gestational age, however, a significant length discrepancy was found only in the 14- to 20-week gestational age range. In this age range, mean cervical length at transperineal ultrasonography (28.6 mm) averaged 5.5 mm less than at endovaginal ultrasonography (34.1 mm). 2
33. Hong JS, Park KH, Noh JH, Suh YH. Cervical length and the risk of microbial invasion of the amniotic cavity in women with preterm premature rupture of membranes. J Korean Med Sci. 2007;22(4):713-717. Observational-Dx 50 singleton pregnancies Prospective observational study to determine whether sonographically measured cervical length is of value in the identification of MIAC in women with preterm premature rupture of membranes and to compare its performance with maternal blood C-reactive protein, white blood cell count, and amniotic fluid white blood cell count. The prevalence of a positive amniotic fluid culture was 26% (13/50). Patients with positive amniotic fluid cultures had a significantly shorter median cervical length and higher median C-reactive protein, white blood cell count, and amniotic fluid white blood cell count than did those with negative cultures. Multiple logistic regression indicated that only cervical length had a significant relationship with the log odds of a positive amniotic fluid culture. TVUS measurement of cervical length is valuable in the identification of microbial invasion of amniotic cavity in women with preterm premature rupture of membranes. Cervical length performs better than amniotic fluid white blood cell count, maternal blood C-reactive protein, and white blood cell count in the identification of a positive amniotic fluid culture. 3
34. Gomez R, Romero R, Nien JK, et al. A short cervix in women with preterm labor and intact membranes: a risk factor for microbial invasion of the amniotic cavity. Am J Obstet Gynecol. 2005;192(3):678-689. Observational-Dx 401 patients To determine whether there was a relationship between sonographic cervical length and the presence of culture-proven MIAC in women with preterm labor and intact membranes. Patients were selected from a prospective cohort study. The prevalence of MIAC was 7% (28/401). Spontaneous preterm delivery (=35 weeks) occurred in 21.4% (82/384) of patients. ROC curve analysis showed a significant relationship between the frequency of MIAC and the length of the uterine cervix (area under the curve: 0.77; P<.005). Patients with a cervical length <15 mm had a higher rate of a positive amniotic fluid culture than patients with a cervical length =15 mm (26.3% [15/57] vs 3.8% [13/344], respectively; P<.05). Moreover, patients with a short cervix (defined as <15 mm) were more likely to deliver spontaneously before 35 weeks, 32 weeks, within 7 days, and within 48 hours of admission ( P<.05 for all comparisons). 40% of patients (161/401) had a cervical length =30 mm. These patients had a very low risk of MIAC (1.9% [3/161]), spontaneous delivery =35 weeks (4.5% [7/154]), =32 weeks (2.6% [2/76]), within 7 days (1.9% [3/154]), and within 48 hours (0% [0/154]) of admission. Endovaginal US examination of the uterine cervix in women with preterm labor identifies patients at increased risk for intrauterine infection. 3
35. Hassan S, Romero R, Hendler I, et al. A sonographic short cervix as the only clinical manifestation of intra-amniotic infection. J Perinat Med. 2006;34(1):13-19. Review/Other-Dx 152 patients with a short cervix at 14-24 weeks Retrospective cohort study to determine the rate of MIAC and intra-amniotic inflammation in patients with a cervical length <25 mm in the mid-trimester. 57/152 patients had amniotic fluid analysis. The prevalence of MIAC was 9% (5/57). Among these patients, the rate of preterm delivery (<32 weeks) was 40% (2/5). Sub-clinical MIAC was detected in 9% of patients with a sonographically short cervix (<25 mm). Maternal parenteral treatment with antibiotics can eradicate MIAC caused by Ureaplasma urealyticum. This was associated with delivery at term in the three patients whose successful treatment was documented by microbiologic studies. 4
36. Friedman AM, Srinivas SK, Parry S, Elovitz MA, Wang E, Schwartz N. Can transabdominal ultrasound be used as a screening test for short cervical length?. Am J Obstet Gynecol. 208(3):190.e1-7, 2013 Mar. Observational-Dx 1217 women To determine whether transabdominal ultrasound be used as a screening test for short cervical length. Prevoid transabdominal cervical length 2
37. American College of Radiology. ACR-SPR Practice Parameter for Imaging Pregnant or Potentially Pregnant Adolescents and Women with Ionizing Radiation. Available at: http://www.acr.org/~/media/ACR/Documents/PGTS/guidelines/Pregnant_Patients.pdf. Accessed September 5, 2014. Review/Other-Dx N/A Guidance document to promote the safe and effective use of diagnostic and therapeutic radiology by describing specific training, skills and techniques. N/A 4
38. American College of Radiology. ACR-ACOG-AIUM-SRU Practice Paramater for the Performance of Obstetrical Ultrasound. Available at: http://www.acr.org/~/media/ACR/Documents/PGTS/guidelines/US_Obstetrical.pdf. Accessed September 5, 2014. Review/Other-Dx N/A Guidance document to promote the safe and effective use of diagnostic and therapeutic radiology by describing specific training, skills and techniques. N/A 4
39. Expert Panel on MR Safety, Kanal E, Barkovich AJ, et al. ACR guidance document on MR safe practices: 2013. J Magn Reson Imaging. 37(3):501-30, 2013 Mar. Review/Other-Dx N/A Guidance document on MR safety practices to help guide MR practitioners regarding MR safety issues and provide a basis for them to develop and implement their own MR policies and practices. N/A 4
40. American College of Radiology. Manual on Contrast Media. Available at: http://www.acr.org/Quality-Safety/Resources/Contrast-Manual. Accessed September 5, 2014. Review/Other-Dx N/A Guidance document on contrast media to assist radiologists in recognizing and managing risks associated with the use of contrast media. N/A 4