Abstract/Text: The objective of this study is to monitor the process of effacement of the uterine cervix and demonstrate that transperineal sonography is the appropriate technique for this purpose. Eighty-six patients with normal, term pregnancies were studied at the beginning of labor. Transperineal sonography was performed in transverse and longitudinal planes. After the initial examination, patients were reexamined several times during a 1 to 4 hour period. We observed a progressive shortening of the canal and the synchronous opening of a funnel-shaped internal cervical os. When the funneling process reached the lower end of the cervix, both orifices fused, completing the process of effacement. The dilatation of the external os, which remained stationary during initial phase, increases very quickly once the effacement has been completed. Transperineal sonography efficiently imaged the changes described here.

Abstract/Text: BACKGROUND: The role of the cervix in the pathogenesis of premature delivery is controversial. In a prospective, multicenter study of pregnant women, we used vaginal ultrasonography to measure the length of the cervix; we also documented the incidence of spontaneous delivery before 35 weeks' gestation.
METHODS: At 10 university-affiliated prenatal clinics, we performed vaginal ultrasonography at approximately 24 and 28 weeks of gestation in women with singleton pregnancies. We then assessed the relation between the length of the cervix and the risk of spontaneous preterm delivery.
RESULTS: We examined 2915 women at approximately 24 weeks of gestation and 2531 of these women again at approximately 28 weeks. Spontaneous preterm delivery (at less than 35 weeks) occurred in 126 of the women (4.3 percent) examined at 24 weeks. The length of the cervix was normally distributed at 24 and 28 weeks (mean [+/- SD], 35.2 +/- 8.3 mm and 33.7 +/- 8.5 mm, respectively). The relative risk of preterm delivery increased as the length of the cervix decreased. When women with shorter cervixes at 24 weeks were compared with women with values above the 75th percentile, the relative risks of preterm delivery among the women with shorter cervixes were as follows: 1.98 for cervical lengths at or below the 75th percentile (40 mm), 2.35 for lengths at or below the 50th percentile (35 mm), 3.79 for lengths at or below the 25th percentile (30 mm), 6.19 for lengths at or below the 10th percentile (26 mm), 9.49 for lengths at or below the 5th percentile (22 mm), and 13.99 for lengths at or below the 1st percentile (13 mm) (P < 0.001 for values at or below the 50th percentile; P = 0.008 for values at or below the 75th percentile). For the lengths measured at 28 weeks, the corresponding relative risks were 2.80, 3.52, 5.39, 9.57, 13.88, and 24.94 (P < 0.001 for values at or below the 50th percentile; P = 0.003 for values at the 75th percentile).
CONCLUSIONS: The risk of spontaneous preterm delivery is increased in women who are found to have a short cervix by vaginal ultrasonography during pregnancy.

Abstract/Text: OBJECTIVE: To estimate if cerclage prevents preterm birth and perinatal mortality and morbidity in women with previous preterm birth, singleton gestation, and short cervical length in a meta-analysis of randomized trials.
DATA SOURCES: MEDLINE, PUBMED, EMBASE, and the Cochrane Library were searched using the terms "cerclage," "short cervix," "ultrasound," and "randomized trial."
METHODS OF STUDY SELECTION: We included randomized trials of cerclage in women with short cervical length on transvaginal ultrasonography, limiting the analysis to women with previous spontaneous preterm birth and singleton gestation.
TABULATION, INTEGRATION, AND RESULTS: Patient-level data abstraction and analysis were accomplished by two independent investigators. Five trials met inclusion criteria. In women with a singleton gestation, previous spontaneous preterm birth, and cervical length less than 25 mm before 24 weeks of gestation, preterm birth before 35 weeks of gestation was 28.4% (71/250) in the cerclage compared with 41.3% (105/254) in the no cerclage groups (relative risk 0.70, 95% confidence interval 0.55– 0.89). Cerclage also significantly reduced preterm birth before 37, 32, 28, and 24 weeks of gestation. Composite perinatal mortality and morbidity were significantly reduced (15.6% in cerclage compared with 24.8% in no cerclage groups; relative risk 0.64, 95% confidence interval 0.45– 0.91).
CONCLUSION: In women with previous spontaneous preterm birth, singleton gestation, and cervical length less than 25 mm, cerclage significantly prevents preterm birth and composite perinatal mortality and morbidity.

Abstract/Text: OBJECTIVE: The purpose of this study was to compare preterm delivery rates and neonatal morbidity/mortality rates for women with cervical incompetence with membranes at or beyond a dilated external cervical os that was treated with emergency cerclage, bed rest plus indomethacin, versus just bed rest.
STUDY DESIGN: Women with cervical incompetence with membranes at or beyond a dilated external cervical os, before 27 weeks of gestation, were treated with antibiotics and bed rest and randomly assigned for emergency cerclage and indomethacin or bed rest only.
RESULTS: Twenty-three women were included; 13 women were allocated randomly to the emergency cerclage and indomethacin group, and 10 women were allocated randomly to the bed rest-only group. Gestational age at time of randomization was 22.2 weeks in the emergency cerclage and indomethacin group and 23.0 weeks in the bed rest-only group. Mean interval from randomization until delivery was 54 days in the emergency cerclage and indomethacin group and 20 days in the bed rest-only group (P=.046). Mean gestational age at delivery was 29.9 weeks in the emergency cerclage and indomethacin group and 25.9 weeks in the bed rest-only group. Preterm delivery before 34 weeks of gestation was significantly lower in the emergency cerclage and indomethacin group, with 7 of 13 deliveries versus all 10 deliveries in the bed rest-only group (P=.02).
CONCLUSIONS: Emergency cerclage, indomethacin, antibiotics, and bed rest reduce preterm delivery before 34 weeks compared with bed rest and antibiotics alone.