Role of acoustic radiation force impulse and shear wave velocity in prediction of preterm birth: a prospective study

Background: Preterm birth is one of the important causes of neonatal morbidity where we rely on subjective criteria such as modified Bishop's scoring and contemporary sonographic measurement of cervical length. Acoustic radiation force impulse (ARFI) is a technological advancement in elastography that can be employed in prediction of cervical softening and preterm labor. Purpose: To evaluate the role of ARFI technique and shear wave velocity (swv) estimates as a predictor of preterm birth and its comparison with other clinical and sono-elastographic measures. Material and Methods: Thirty-four pregnant women (gestation age = 28-37 weeks age) showing features suggestive of preterm labor were included and evaluated with modified Bishop's score, cervical length by ultrasound (US), ARFI to derive Elastography index , and SWV of the cervix. The patients were later divided into two groups, using the clinical outcome of preterm or term delivery. Results: Twenty patients delivered at term (gestational age > 37 weeks) and 14 were preterm. Receiver operating characteristics (ROC) curves showed SWV with highest sensitivity and specificity (93% and 90%, respectively) for the prediction of preterm birth at a cutoff value of 2.83 m/s El and modified Bishop's score were comparable to each other, but were less sensitive techniques. Conclusion: Elastographic assessment of antenatal cervix is a novel technique of virtual palpation of internal os and can be utilized as an objective criterion for preterm birth prediction.