EP19.11: Ultrasound markers as predictors for Foley catheter expulsion during induction of labour

Labour induction (IOL) does not increase the risk of obstetric or perinatal outcomes, even more – it has benefits. The aim of the study was to see if there is any correlation between ultrasound parameters assessed before induction of labour and the time of Foley catheter expulsion, used as a method of IOL. A prospective study was conducted in Riga Maternity hospital from January 2021 to February 2024. Nulliparous women with singleton pregnancy, cephalic presentation, intact membranes and Bishop score 6 or less with indication of IOL at term were included. Before the IOL with a combined method–Foley catheter and Misoprostol orally, ultrasound markers were evaluated. Prior to IOL cervical length, posterior cervical angle, subpubic angle, head-perineum distance, and elastography index (EI) by GE Versana Premier were assessed. Correlations between objective ultrasound parameters and time to Foley catheter expulsion after beginning of IOL were estimated using Spearman's correlation coefficient. The study included 146 patients. Median time from the start of IOL till Foley catheter expulsion was 7h 29min (Quartile 1 - 5h 7min; Quartile 2 - 9h 31min). There is a correlation between cervical length before the start of IOL and Foley catheter expulsion, (p = 0.009), with no significant influence of other parameters on the time of catheter expulsion. Neither posterior cervical angle and subpubic angle, elastography index and head-perineum distance do not have strong correlation with the time of Foley catheter expulsion. Given the lack of potential weak correlations in ultrasonographic parameters, it is possible that the time period from the IOL to expulsion of Foley catheter is insufficient to be to evaluated. Acknowledgement: This research is funded by the Latvian Council of Science project “Role of Metabolome, Biomarkers and Ultrasound Parameters in Successful LI”, No.lzp-2021/1-0300