The Effect of Preinduction Cervical Ripening With Synthetic Hygroscopic Dilators on Maternal Outcomes of Women With Previous Caesarean Pregnancy: A Single-Group Clinical Trial.

Background: Preinduction cervical ripening in previous caesarean pregnancy is limited to intracervical Foley catheter. This study is aimed at finding the vaginal birth rates, improvement of Bishop score, and safety of osmotic dilator (Dilapan-S) among women with previous caesarean pregnancy. Methods: We conducted this single-group clinical study after the approval of the institute ethics committee, clinical trial registration, and obtaining informed consent. We recruited women above 18 years with a prior caesarean section at term and a Bishop score of less than 6 by systematic random sampling prospectively. The first or second author inserted two to a maximum of five osmotic dilators (Dilapan-S) in the cervical canal. After 24 h, we removed Dilapan and induced labour with a low-dose oxytocin regimen up to a maximum dose of 24 mIU/min. We assessed the improvement of the Bishop score and vaginal birth rates for efficacy and safety concerns like bleeding, fragmentation, displacement, infections, and scar dehiscence. Results: Eighty-two women completed the study. The Bishop score significantly improved from a mean of 2.6 before to 5.3 after Dilapan. Three opted for a caesarean section after Dilapan removal and refused oxytocin infusion. Seventy-nine women completed the trial of labour. Forty-one (52%) achieved active labour (52%). Twenty-seven delivered vaginally, and 52 required emergency caesarean section (34% vaginal birth rate; 18 spontaneous, nine instrumental, four with forceps, and five with vacuum). None had entrapment, fragmentation, or upward displacement of Dilapan. Two women had scar dehiscence, and one had a traumatic postpartum haemorrhage. There was no maternal or perinatal mortality. Conclusions: We conclude that the hygroscopic dilator Dilapan effectively ripens the cervix before labour induction in women with a previous caesarean scar. They are safe, but more extensive studies are needed to evaluate scar-related complications during labour. Trial Registration: Clinical Trial Registry of India: CTRI/2019/03/017927.