Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Semin Perinatol. 2009 Oct;33(5):317-24. doi: 10.1053/j.semperi.2009.06.007.
The cervix has to open to allow vaginal birth. Ultrasound has now shown that this lower part of the uterus begins to show changes weeks before eventual birth. Only transvaginal ultrasound should be used to evaluate the cervix for prediction of preterm birth (PTB). The shortest best cervical length (CL) is the most effective measurement for clinical use. Proper technique is paramount for accurate results. The risk of PTB increases with ever shorter CL (<25 mm). Other factors that must be carefully considered when using CL for prediction of PTB are number of fetuses, risk factors for PTB, and gestational age at screening.
宫颈必须张开才能允许阴道分娩。现在超声检查已经表明，子宫的下部在最终分娩前几周就开始出现变化。只有阴道超声检查才能用于评估宫颈以预测早产 (PTB)。最短的最佳宫颈长度 (CL) 是最有效的临床测量方法。准确的结果离不开正确的技术。CL 越短（<25mm），PTB 的风险就越大。在使用 CL 预测 PTB 时，还必须仔细考虑其他因素，如胎儿数量、PTB 的危险因素以及筛查时的孕龄。
