If 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), transperineal US is a suitable alternative. If transperineal US is performed, the above caveats regarding CL in the early second trimester should be noted. US Cervix Transvaginal TVUS allows for the most complete assessment of the cervix, yet its use in universal screening of low-risk women remains controversial. Supportive evidence for universal screening comes from two studies evaluating the rates of PTB before and after implementation of a universal transvaginal cervical screening program [29,30]. Following implementation of their screening program, Son et al [29] demonstrated statistically significant decreases in the rates of spontaneous PTB <37 weeks (4.8% versus 4.0%), <34 weeks (1.3% versus 1.0%), and <32 weeks (0.7% versus 0.5%). Temming et al [30] demonstrated similar findings following implementation of their screening program; however, statistically significant decreases only were observed in the rates of spontaneous PTB <28 weeks (2.0% versus 0.7%) and <24 weeks (1.5% versus 0.35%). Other studies demonstrate no clear benefit to transvaginal screening, thereby calling into question its appropriateness. In one study evaluating a CL screening program in nulliparous women, no statistical difference was observed in the rate of spontaneous PTB in patients who underwent screening compared with those who did not [31]. In a separate study of nulliparous women, the predictive accuracy of serial TVUS for spontaneous PTB Although TVUS is not contraindicated in the setting of placenta previa, it should be performed using real-time imaging as the probe is advanced.
Assessment of Gravid Cervix. If 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), transperineal US is a suitable alternative. If transperineal US is performed, the above caveats regarding CL in the early second trimester should be noted. US Cervix Transvaginal TVUS allows for the most complete assessment of the cervix, yet its use in universal screening of low-risk women remains controversial. Supportive evidence for universal screening comes from two studies evaluating the rates of PTB before and after implementation of a universal transvaginal cervical screening program [29,30]. Following implementation of their screening program, Son et al [29] demonstrated statistically significant decreases in the rates of spontaneous PTB <37 weeks (4.8% versus 4.0%), <34 weeks (1.3% versus 1.0%), and <32 weeks (0.7% versus 0.5%). Temming et al [30] demonstrated similar findings following implementation of their screening program; however, statistically significant decreases only were observed in the rates of spontaneous PTB <28 weeks (2.0% versus 0.7%) and <24 weeks (1.5% versus 0.35%). Other studies demonstrate no clear benefit to transvaginal screening, thereby calling into question its appropriateness. In one study evaluating a CL screening program in nulliparous women, no statistical difference was observed in the rate of spontaneous PTB in patients who underwent screening compared with those who did not [31]. In a separate study of nulliparous women, the predictive accuracy of serial TVUS for spontaneous PTB Although TVUS is not contraindicated in the setting of placenta previa, it should be performed using real-time imaging as the probe is advanced.