The ‘virtual’ cervical internal os: diagnosis during the first trimester of pregnancy

Abstract

Objective To determine the appropriate time during gestation for assessing the cervix for possible incompetence by ascertaining the gestational week at which the sac reaches the level of the internal os. Methods

Transvaginal ultrasound measurement of cervical length and efficacy of misoprostol in first‐trimester pregnancy failure

“…As our first choice we used the standard method, which involves determination of the border between the cervical canal and the beginning of the endometrium10. This method did not, however, allow us to identify the internal os in all cases, and in such cases we used the indirect method described by Shalev et al 11.…”

“…The VC is the upper limit of the cervical glands, which are hypoechoic and quite distinct from the lower segment10. If we could not identify the glands, we used the method described by Shalev et al 11: the vesical caudal apex was projected vertically against the long axis of the cervical canal to obtain the VC. Sonographic variables were measured using a Hitachi (Paris, France) ultrasound machine equipped with a 3.5‐MHz convex probe.…”

Ultrasound examination of the cervix to predict preterm delivery: we still know too little to use it in clinical practice

“…It is important to determine whether cervical measurements obtained using one measurement technique are more predictive of preterm delivery than those obtained using another measurement technique (e.g., if cervical length measurements obtained after transfundal pressure are more predictive than measurements obtained without transfundal pressure; if the use of the shortest cervical length is more predictive than the use of the mean of repeated measurements; if measurements of a curved cervix are more predictive when taken following the curvature of the cervix or when taken as a straight line between the inner and outer cervical os). An article discussing the technique of examining the cervix in the first trimester is published in this issue of the Journal30. Shalev et al conclude that the gestational sac does not reach the inner cervical os until 12 gestational weeks, and that therefore the inner cervical os cannot be evaluated for the presence or absence of funneling before that time.…”