Sonoelastography for the comparative assessment of cervical maturation after different approaches to cervical preparation ahead of labor induction

Abstract

Aim To compare the efficacy of different approaches to cervical preparation to labor induction using the ultrasound cervical elastography. Materials and methods This prospective open-label study included 200 pregnant women aged between 23 and 38 years eligible for labor pre-induction. Patients were divided into four groups (n = 50 per group). In Group I, four osmotic Dilapan-S cervical dilators combined with two doses of oral mifepristone (200 mg each) 24 h apart were used. The dilators were inserted for up to 12 h. In Group II, only the Dipalan-S dilators were used. In Group III, a Foley catheter was positioned intracervically for 12 h. In Group IV, we used two doses of intracervical prostaglandin E2 gel (0.5 mg each) 6 h apart. Cervical maturation was assessed using the Bishop scoring system and the ultrasound cervicometry with the color mapping and calculation of SR ratio. At baseline, all participants were also divided into three subgroups depending on the Bishop score before the pre-induction. Subgroup А (n = 66) included patients with the Bishop score between 0‒2 points, subgroup B (n = 69) between 3–4 points, and subgroup С (n = 65) between 4–6 points. Results Our study showed that the efficacy of Dilapan-S combined with mifepristone for cervical preparation to labor induction was higher than Dilapan-S, Foley catheter and intracervical prostaglandin E2 gel. In this group, the Bishop score after the pre-induction was the highest (11.4 (0.21) points versus 10.2 (0.2), 9.4 (0.3) и 9.67 (0.25) in Groups II, III and IV respectively (p < .05 for all). The lowest SR values were also observed among the patients receiving the combination of Dilapan-S and mifepristone: 1.23 (0.04) versus 1.63 (0.07), 1.7 (0.08) and 1.83 (0.1) in Groups II, III and IV respectively (p < .05 for all). The sonoelastographic SR values in subgroups B and C were statistically lower compared with subgroup A across all groups studied. Ultrasound elastography of the cervix allowed to perform a more objective assessment of cervical maturation compared with the Bishop scoring. Conclusion Dilapan-S combined with mifepristone had higher efficacy for cervical preparation to labor induction compared with other approaches investigated.