P01.03: Ultrasound assessment of cervical length and volume: comparison of transabdominal and transvaginal approach

Abstract

We investigate the reliability of transabdominal (TA) 3D measurements of the cervical volume (CV) by comparison with transvaginal sonography for CV measurement. All singleton pregnancies were included and women who already had a diagnosis of preterm labour, PROM, IIOC in the current pregnancy were excluded. For determination of the CV using VOCAL software. We assessed the correlation of TA and TV measurements. In addition, the discrepancies between TA and TV sonography were analysed to investigate the practical usefulness of TA sonography for the variable maternal and fetal conditions. A paired t test and Pearson correlation were used to compare the two parameters according to approach method. A total of 300 pregnant women were enrolled in this study. The mean GA was 33±3.6 years. The mean CL and CV were 34.5 ± 9.5 cm and 35.1 ± 12.9cm3 on TAS and 33.5 ± 9.7 cm and 35.1 ± 12.9cm3 on TVS, respectively. There was no significant difference between these means of CL and CV(Pearson r = 0.76 vs r=0.91, respectively). There are no significant discrepancy between TV and TA measurement of both parameter for the variable fetal and maternal condition; fetal presentation, maternal abdominal wall thickness, bladder filling state, maternal age, amniotic fluid index. Preterm birth group (N=16, 7.4%) had more shorter and smaller TV CL, CV(30.0 ± 12.1mm vs 34.0 ± 0.93mm, p 0.01 and 29.30 ± 9.3 cm3 vs 35.47 ± 13.14 cm3 p 0.03, respectively) than term birth group. CV measurement did not add any benefit compared with the CL measurement for prediction of preterm birth. But in subgroup analysis, CV measurement had additional benefit compared with the CL for prediction of preterm birth in normal cervical length group. In conclusion, the evidence for the clinical application of cervical volume screening is still insufficient. If TA CL is normal, it could be useful to try the TACV measurement. This step-by-step approach may be more convenient and useful to both patients and physicians for cervical length screening.