If assessment of the cerclage is performed, additional measurements irrespective of approach (eg, transabdominal, transvaginal, or transperineal) may include the total length of closed cervix regardless of cerclage sutures, and if funneling is present, the length of closed cervix from the level of cervical funneling to the level of the cerclage sutures. Variant 3: Assessment of gravid cervix. Suspected preterm labor. Initial imaging. US Cervix Transabdominal To our knowledge, there is no relevant literature regarding the use of transabdominal US in the evaluation of the cervix for suspected preterm labor. US Cervix Transperineal Transperineal US is an alternate approach to transvaginal evaluation of the gravid cervix. In one study, adequate visualization of the cervix was achieved in 82% of patients in preterm labor with good agreement of transperineal and transvaginal measurements with an intraclass correlation coefficient of 0.83 [40]. The mean difference in cervical measurements between transperineal and transvaginal approaches was 1.5 mm, with transperineal US underestimating CL in most cases. No significant disagreement between both methods was observed above or below a length of 25 mm. A study by Dimassi et al [41] also reported a strong correlation in CL obtained by both methods as well as a low mean difference in cervical measurements (0.38 mm). TVUS would be preferred for assessment of the cervix in cases of suspected preterm labor. Nevertheless, transperineal US would be an adequate alternative in the event that TVUS is declined by the patient or if the risk of TVUS is deemed too high (eg, placenta previa, suspected preterm premature rupture of membranes). Assessment of Gravid Cervix US Cervix Transvaginal TVUS is the reference standard of imaging modalities used for assessment of the gravid cervix because it allows for complete visualization of the cervix, including the internal os where changes of PTB first occur. Transvaginal imaging is highly reproducible.
Assessment of Gravid Cervix. If assessment of the cerclage is performed, additional measurements irrespective of approach (eg, transabdominal, transvaginal, or transperineal) may include the total length of closed cervix regardless of cerclage sutures, and if funneling is present, the length of closed cervix from the level of cervical funneling to the level of the cerclage sutures. Variant 3: Assessment of gravid cervix. Suspected preterm labor. Initial imaging. US Cervix Transabdominal To our knowledge, there is no relevant literature regarding the use of transabdominal US in the evaluation of the cervix for suspected preterm labor. US Cervix Transperineal Transperineal US is an alternate approach to transvaginal evaluation of the gravid cervix. In one study, adequate visualization of the cervix was achieved in 82% of patients in preterm labor with good agreement of transperineal and transvaginal measurements with an intraclass correlation coefficient of 0.83 [40]. The mean difference in cervical measurements between transperineal and transvaginal approaches was 1.5 mm, with transperineal US underestimating CL in most cases. No significant disagreement between both methods was observed above or below a length of 25 mm. A study by Dimassi et al [41] also reported a strong correlation in CL obtained by both methods as well as a low mean difference in cervical measurements (0.38 mm). TVUS would be preferred for assessment of the cervix in cases of suspected preterm labor. Nevertheless, transperineal US would be an adequate alternative in the event that TVUS is declined by the patient or if the risk of TVUS is deemed too high (eg, placenta previa, suspected preterm premature rupture of membranes). Assessment of Gravid Cervix US Cervix Transvaginal TVUS is the reference standard of imaging modalities used for assessment of the gravid cervix because it allows for complete visualization of the cervix, including the internal os where changes of PTB first occur. Transvaginal imaging is highly reproducible.