Reliability of new three-dimensional ultrasound technique for pelvic hiatal area measurement.

OBJECTIVE: To assess the reproducibility of a new technique for three-/four-dimensional (3D/4D) ultrasound imaging of the pelvic floor: OmniView™ volume contrast imaging (VCI) for measurement of the pelvic hiatal area on maximum contraction and Valsalva maneuver. In addition, we aimed to study the intermethod agreement between the new technique and the 3D/4D render method. METHODS: We acquired one static 3D and two dynamic 4D transperineal volumes (one obtained during contraction and one during Valsalva maneuver) from 35 nulliparous asymptomatic healthy volunteers and 35 women with symptoms of pelvic floor dysfunction. Each 3D dataset was analyzed using the OmniView-VCI technique to measure the pelvic hiatal area at rest, on maximum contraction and on maximum Valsalva. Analysis was performed twice by the same operator and once by another operator in order to assess intra- and interobserver reproducibility. All measurements were repeated by one operator using the 3D/4D render method to evaluate the intermethod agreement. Reproducibility and intermethod agreement were studied by means of intraclass correlation coefficients (ICC) and the Bland-Altman method. RESULTS: Measurement of hiatal area using the OmniView-VCI technique showed excellent intraobserver and interobserver reproducibility in both asymptomatic and symptomatic women at rest, on contraction and on Valsalva maneuver. In addition, excellent agreement was demonstrated between OmniView-VCI and 3D/4D render in both groups (ICCs on Valsalva in asymptomatic and symptomatic women were 0.894 and 0.975, respectively). No systematic difference was noted in any of the reliability studies performed. CONCLUSIONS: OmniView-VCI is a reliable method for pelvic hiatal area measurement. Both rendering mode and OmniView-VCI can be used interchangeably for assessing pelvic hiatal area. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Sonographic evaluation of the lower uterine segment thickness in women with a single previous Cesarean section.

AIM: The aim of this paper was to evaluate the lower uterine segment (LUS) thickness through transvaginal sonography in late preterm and full term pregnancies with a single previous Cesarean section, to correlate the obtained LUS measurements with intraoperative observations, and to identify a predictive cut-off value in order to select the best candidates for a vaginal birth after Cesarean delivery (VBAC). METHODS: Two hundred and fourteen women with a single previous Cesarean section who had an ultrasound measurement of the LUS thickness (stratified in S1, S2 and S3) in pregnancy were enrolled. The outcome of interest was the visual finding of a thin uterine scar at the time of the iterative Cesarean section. Linear regression was used to correlate the LUS thickness with gestational age (GA). A ROC curve has been used to determine the detection rate (DR) and the risk of each actual value of LUS thickness versus a thin uterine scar (outcome of interest). RESULTS: The LUS thickness was correlated with the gestational age (R2=0.034, P-value =0.005). The DR as estimated by ROC curves to detect a translucent lower uterine segment (S3) was 94.1% at a false positive rate (FPR) of 20%. The correspondent cut-off value was 1.8 mm. Finally a likelihood ratio (LR) of observing S3 was estimated. At the quoted cut-off of 1.8 mm the LR was 3. As demonstrated, for a segment of 1 mm the LR was instead about 13. CONCLUSION: The obtained values lead us to the conclusion that a thickness less than 1.8 mm can be reasonably considered a valid cut-off value to identify patients with a higher risk of thin uterine scar.