Transvaginal sonographic assessment of cervical dynamics during the third trimester of normal pregnancy

Abstract

There is a direct relationship between both cervical width and length and gestational age and an inverse relationship with cervical length and the duration of labor. Funnelling of the internal os was not a predictor of the early onset of labor. The dimensions and features of the Asian cervix differ from those of the Europeans, and this should be considered when conducting further studies of a similar nature.

Reference data representative of normal findings at two‐dimensional and three‐dimensional gray‐scale ultrasound examination of the cervix from 17 to 41 weeks' gestation

“…After 32 weeks we would recommend separate reference values for nulliparous women and parous women and separate reference values depending on pregnancy week. Our results with regard to cervical length agree with those reported by Tongsong et al 16 and Brieger et al 15 . Tongsong et al 16 found cervical length did not change substantially between 8 and 31 weeks, and thereafter it 52 34 26 46 27 29 21 29 45 33 45 23 9 32 28 27 30 27 29 20 33 28 34 37 25 decreased.…”

“…In all studies where cervical AP diameter was measured and compared between nulliparous and parous women it tended to be larger in parous women 17,18 , and in all studies AP diameter increased with gestational age 12,15,17,18 . This is in agreement with the present results.…”

“…Tongsong et al 16 found cervical length did not change substantially between 8 and 31 weeks, and thereafter it 52 34 26 46 27 29 21 29 45 33 45 23 9 32 28 27 30 27 29 20 33 28 34 37 25 decreased. Brieger et al 15 reported decreasing cervical length from 30 weeks. Results of other studies are more variable: some found that cervical length did not change during pregnancy 12 , others found a continuous decrease from 10 to 40 weeks 13 or from 17 to 37 weeks 20 , while others still 14 reported that the cervix became longer between 8 and 25 weeks and then shortened.…”

“…The discrepant results may be explained by differences in measurement technique, study design, the period in gestation studied, the statistical methods used, and the interpretation of the results. For example, in some studies 13,15,16,19,20,28 a correlation coefficient was used to describe changes in cervical length with gestational age. Only Gramellini et al 13 , Murakawa et al 20 and Brieger et al 15 reported a strong or moderate negative correlation between cervical length and gestational age (r = 0.92, P < 0.001, r = 0.4, P < 0.001 and σ = 0.6, P < 0.001) compared with the other studies 16,19,28 where the negative correlation was weak.…”

“…The published studies cover different periods of gestation, have different study designs, and the study populations are mixed and/or small. There are only a few studies where reference values for cervical AP diameter 12,15,17,18 are presented, but to the best of our knowledge no reference values for cervical funneling have been published. In three small studies, cervical length 9,10,21 and funneling 9,10 were assessed by 3D ultrasound.…”