TRANSVAGINAL SONOGRAPHIC ASSESSMENT OF CERVICAL DYNAMICS DURING THE 3RD-TRIMESTER OF NORMAL-PREGNANCY

Background. To obtain a normogram of measurements of the uterine cervi x by transvaginal sonography during the third trimester of normal prim iparous pregnancies and to relate these measurements to the events sur rounding labor. Methods. A prospective observational study, set in Gua ngzhou, Peoples Republic of China, was undertaken. Fifty-five normal n ulliparous Chinese women with singleton pregnancies were studied from 30 weeks gestation until delivery. Serial transvaginal ultrasound exam inations were performed at 30, 32, 34 and 36 weeks gestation and weekl y thereafter. Results. There was a significant correlation between ges tational age and cervical length and width. Funnelling of the internal os was present in 25% of casts, and its earliest appearance was ar 36 weeks. There was no consistent relationship between funnel length and width and gestational age. The duration of the first stage of labor w as inversely correlated with the last ultrasound measurement of cervic al length, but there was no relationship with tither cervical width no r tile presence of funnelling. The cervical changes in this population differed from those found in Caucasians. Conclusions. There is a dire ct 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 ea rly onset of labor. The dimensions and features of the Asian cervix di ffer from those of the Europeans, and this should be considered when c onducting further studies of a similar nature.