Value of cervical electrical impedance spectroscopy to predict spontaneous preterm delivery in asymptomatic women: the ECCLIPPx prospective cohort study

• Published in: Ultrasound in obstetrics & gynecology 2021-08, Vol.58 (2), p.293-302
• Main Authors: Anumba, D. O. C., Stern, V., Healey, J. T., Dixon, S., Brown, B. H.
• Format: Article
• Language: English
• Subjects: Accuracy; Adult; Asymptomatic; Birth; cervical length; Cervical Length Measurement; Cervix; Cervix Uteri - diagnostic imaging; Cohort analysis; Cohort Studies; Dielectric Spectroscopy; Electrical impedance; electrical impedance spectroscopy; Female; fetal fibronectin; Fetuses; Fibronectin; Frequency ranges; Gestation; Gynecology; Humans; Impedance; Impedance spectroscopy; Model accuracy; Obstetrics; Performance prediction; Prediction models; Pregnancy; Premature birth; Premature Birth - prevention & control; Prenatal Diagnosis; preterm birth; Prospective Studies; Regression analysis; screening; Sensitivity and Specificity; Spectroscopy; Spectrum analysis; Ultrasonic imaging; Ultrasonic testing; Ultrasound; Womens health
• ISSN: 0960-7692; 1469-0705
• DOI: 10.1002/uog.22180

ABSTRACT Objectives Preterm birth (PTB) accounts for two‐thirds of deaths of structurally normal babies and is associated with substantial lifetime healthcare costs. Prevention of PTB remains limited by the modest accuracy of prediction methods, namely transvaginal ultrasound (TVS) cervical length (CL) measurement and quantitative cervicovaginal fetal fibronectin (FFN) estimation. We report the first substantive study detailing the predictive performance of a cervical probe device based on electrical impedance spectroscopy (EIS) for PTB – the EleCtriCaL Impedance Prediction of Preterm birth by spectroscopy of the cervix (ECCLIPPx) study. We aimed to compare the accuracy of cervical EIS‐based prediction of spontaneous PTB with that of prediction using TVS‐CL and FFN in asymptomatic women in the mid‐trimester. Methods We studied asymptomatic women with a singleton pregnancy at 20–22 weeks' and 26–28 weeks' gestation. EIS was performed using a Sheffield Mark 5.0 device that makes measurements in the frequency range 76 Hz to 625 kHz using a small probe housing tetrapolar electrodes. TVS‐CL and FFN were also measured. The associations of cervical EIS, TVS‐CL and FFN with spontaneous delivery before 37 weeks and before 32 weeks were determined by multivariate linear and non‐linear logistic regression analysis. Areas under the receiver‐operating‐characteristics curves (AUC) plots of sensitivity against specificity were used to compare the predictive performance of all parameters, both in isolation and in combination. Results Of the 365 asymptomatic women studied at 20–22 weeks who were not receiving treatment, 29 had spontaneous PTB, 14 had indicated PTB and 322 had term birth. At the higher frequencies assessed, cervical EIS predicted spontaneous PTB before 37 weeks with an AUC of 0.76 (95% CI, 0.71–0.81), compared with AUCs of 0.72 (95% CI, 0.66–0.76) for TVS‐CL and 0.62 (95% CI, 0.56–0.72) for FFN. Combining all three assessments improved the prediction of spontaneous PTB before 37 weeks (AUC, 0.79 (95% CI, 0.74–0.83)) compared with TVS‐CL and FFN alone. Incorporating a history of spontaneous PTB (defined as previous mid‐trimester miscarriage or spontaneous PTB (14 to