Ultrasound differentiation of the competent from the incompetent cervix: Prevention of preterm delivery

Cervical length and prediction of preterm delivery

“…Digital and TVU examinations of cervical length every 2 weeks from 14 to 30 weeks' gestation both independently predict PTB, but TVU has a much stronger association with TVU than manual examination of the cervix [7]. The relative lack of success of digital exam in predicting PTB is probably due to the fact that it is subjective (inter-observer variability of 52%) [8], not accurate for evaluating the internal os [9], and nonspecific (15-16% of primiparous women and 17-35% of multiparous women who are delivered at term have cervices that are 1-2 cm dilated by manual examination in the late second trimester) [10]. Sonographic cervical length measurements are, on the average, 11 mm longer than manual estimations.…”

Measuring the Cervical Length

“…The idea of the cervix as a dynamic organ was proposed early in this process, and it was recognized that cervical ''incompetence'' and preterm labor may not be distinct entities. 6,7 Our understanding of cervical function underwent further expansion starting in 1986 with the first report of the use of transvaginal ultrasonography (TVUS) to evaluate the cervix. 8 This specific publication was notable for the description of the Y-V-U phenomenon associated with progressive preterm labor (later expanded to the T-Y-V-U description, discussed further below).…”

Monitoring the effacement of the uterine cervix by transperineal sonography: a new perspective.

“…Nevertheless, this is a common clinical practice recently proposed in the literature.B . 16 We think that it is more accurate to describe morphologic changes of the ICO and to measure the length of the canal and the dilatation of the ECO at the same time, as shown in Table 1. In our protocols we used letters T, Y, V, and U to describe progressive stages of effacement in a quick, visual way.…”