EP17.21: Quantitative cervical elastography and cervical length as a more accurate predictor of preterm birth

This study was conducted to determine whether the addition of quantitative cervical elastography (E-Cervix) hardness ratio to cervical length can more accurately predict preterm birth than cervical length alone. This retrospective study included all women who presented with symptoms of preterm labour at age of gestation between 24 and 36 6/7 weeks who had a transvaginal ultrasound scan done with cervical length and elastography measurements. Cervical elastography was obtained using the E-Cervix system, a semiautomatic software tool that measures the stiffness of the cervix. A total of 68 patients presented with symptoms of preterm labour between 24 and 36 6/7 weeks. Of the 22 preterm deliveries, 9 (40.91%) had a shortened cervix, while 15 (68.18%) had a hardness ratio less than 35%. Eight (36.36%) had both shortened and soft cervix on cervical evaluation, 1 (4.55%) had shortened cervix but with hardness ratio > 35%, 7 (31.82%) had cervix > 2.5cm but hardness ratio < 35%, and 6 (27.27%) had cervix > 2.5 cm and hardness ratio > 35%. The positive and negative predictive values were 64.29% and 75.93% for cervical length alone, 55.56% and 82.93% for hardness ratio alone, and 80% and 83.78% for combined cervical length and hardness ratio. This study showed that the addition of hardness ratio to cervical length alone increased the positive predictive value for preterm delivery from 64.29% to 80%, and the negative predictive value from 75.93% to 83.78%. This allows a more discriminate use of interventions such as the use of vaginal progesterone for patients who would truly benefit from it. Moreover, it had an excellent negative predictive value of 83.78%, meaning that it can identify a group of women who are at low risk for preterm delivery, and reassure these women accordingly. In conclusion, as a response to the limitation of cervical length measurement in predicting preterm birth, the addition of cervical elastography E-Cervix hardness ratio has great potential as a better prediction tool for preterm birth.