Cervical length at 23 weeks of gestation: relation to demographic characteristics and previous obstetric history

Abstract

Transvaginal sonographic measurement of cervical length is highly reproducible and it is associated with a minimal degree of discomfort to the patients. At 23 weeks, the median cervical length is 38 mm and, in 1.6% of the population, the length is 15 mm or less. There is an association between cervical length and demographic characteristics and previous obstetric history.

Cervical length measurement: Comparison of transabdominal and transvaginal approach

“…, 15 Intra‐observer variability was low (3.5%) confirming previous reports that TV measurements are reproducible 6 . The data show that cervical length is not normally distributed; in line with the previous observations of Solomon, et al 22 While the cervix appears to have stable length < 24 weeks, there is then a gradual reduction in cervical length of approximately 1mm per week gestation thereafter; these cross‐sectional data are consistent with previous longitudinal assessment, showing a decay rate of 0.5 mm / week gestation 23 .…”

“…Cervical length is affected by a range of factors that need to be considered for accurate assessment. These include demographic differences, such as gestational age, maternal age, parity and ethnicity, the quality of antenatal care, nutrition, smoking and alcohol intake 6 . The cervix lengthens with increasing bladder volume (Figure 1) and as increased transducer pressure is applied 7 .…”

“…The process of cervical effacement and shortening appears to start at the internal cervical os, leading to funneling that may be revealed by applying fundal pressure 8 . The cervix is dynamic and protocols that standardise measurement recommend making multiple measurements over a five minute period of assessment 6 . Algorithms that describe individualised levels of risk of preterm delivery have been proposed 9 .…”

Prediction of patient‐specific risk of early preterm delivery using maternal history and sonographic measurement of cervical length: a population‐based prospective study

“…Sonographic measurement of cervical length is an easy skill to learn for sonographers undertaking routine ultrasound examination in pregnancy, and whilst formal studies of cost-effectiveness are lacking, the infrastructure and equipment needed for screening are readily available in all maternity units. Studies have documented that transvaginal sonography is acceptable to pregnant women and the vast majority do not experience any discomfort 18,19 . Some women will be falsely classified as high risk and consequently may suffer unnecessary anxiety or intervention; however, the high accuracy and specificity of the test ensure that the number affected will be minimal.…”

Transvaginal cervical length measurement for prediction of preterm birth in women with threatened preterm labor: a meta‐analysis

“…More specifically, scan methodology was considered adequate when performed as described by Heath et al 13 and Andersen et al 14 , otherwise inadequate or not stated. Briefly, the appropriate ultrasound methodology for transvaginal measurement of cervical length involves emptying the urinary bladder, placement of the probe in the anterior fornix, acquisition of a midsagittal view of the cervix and the endocervical mucosa and measurement of the distance between the triangular area of echodensity at the external os and the V-shaped notch at the internal os.…”