Correlation of transabdominal and transvaginal sonography for the assessment of uterocervical angle at 16-24 weeks' gestation.

The objective of this study was to determine the correlation between transabdominal TAS and transvaginal sonography TVS uterocervical angle UCA measurement in pregnant women with no history of previous preterm birth. A cross-sectional study involving singleton pregnancies between 16 and 24 weeks of gestation who underwent routine foetal anatomical scan was conducted. The TAS-UCA measurement was performed before voiding and with an empty bladder. A total of 256 women completed the sonography. The mean maternal age was 32 ± 6.68 years. The mean gestation age at the time of ultrasound assessment was 19 ± 1.71 weeks. The mean prevoid TAS-UCA was 119.74 ± 33.12° and the mean postvoid TAS-UCA was 110.73 ± 25.30°. There was a significant difference between prevoid and postvoid TAS-UCA measurement  < .05 The mean TVS-UCA was 103.91 ± 26.42°. The Pearson correlation coefficients of prevoid and postvoid TAS-UCA with TVS-UCA were 0.438 and 0.601, respectively. In conclusion, the postvoid TAS-UCA has moderate correlation with TVS-UCA measurement and is better than the prevoid TAS-UCA in women with low risk for preterm birth.IMPACT STATEMENT TVS is the gold standard for cervical length (CL) assessment for prediction preterm birth. However, TVS requires an experienced or trained sonographer and some women decline TVS because of the embarrassment and discomfort during examination. Several studies have demonstrated the correlation between TAS and TVS and suggested that TAS could be an alternative for CL screening. UCA has been reported as a new predictor of spontaneous preterm birth and is usually performed by TVS. Thus, it is interesting to evaluate whether TAS can be a substitute procedure for TVS in UCA measurement. TAS may be used as a substitute procedure for TVS and the postvoid TAS is more appropriate than prevoid TAS for UCA measurement. TAS may be an alternative method for UCA measurement when TVS is unavailable or in pregnant women who decline TVS-UCA measurement. However, further study should be conducted to confirm the association between TVS-UCA and postvoid TAS-UCA before deciding to use postvoid TAS-UCA as a screening tool for preterm prediction.