Labor that begins between 20 and 37 weeks gestation is appropriately termed preterm labor. Some of the precipitating factors of preterm labor are changes in cervical status including dilatation and effacement. Until recently, a digital pelvic examination was considered the gold standard for evaluating cervical changes. Current research promotes the use of sonography for the prediction of preterm labor. It is essential for sonographers to become familiar with the various methods of cervical imaging including transabdominal, translabial, and transvaginal approaches. Each technique has its costs and benefits; however, a review of the current literature will show that the transvaginal method of cervical measurement is the most reliable.
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