EP19.17: PROPENSITY‐instrumental delivery study protocol

Failed instrumental delivery (ID) and adverse labour outcomes following combined clinical and intrapartum US assessment of the fetal head position vs standard approach: PROPENSITY-ID study protocol ID in the 2nd stage of labour expedites births in dystocia or non-reassuring fetal conditions (3-15%). ID may prevent complex Caesareans, but failed ID is reported in 4-6% and is associated with increased rates of both maternal and fetal complications. Fetal malposition and malpresentation are among the leading cause of failed ID. The assessment of fetal head position performed by means of digital examination has been shown to be of limited accuracy particularly in the case of OP presentation and with the level of the presenting part at mid- cavity. Intrapartum US has proven to be highly reliable tool for assessing fetal position and represents the gold standard for diagnosing occipital position. On this basis, international guidelines recommend intrapartum US in case of uncertain occiput position prior to performing an ID. Nonetheless, to date no evidence supports the role of intrapartum US in improving labour outcomes by reducing failed ID. This could be due to the low occurrence of adverse outcomes or by the fact that RCT evaluating such outcome are unlikely to be feasible. The PROPENSITY-ID study is a multicentre, international, prospective study aiming to evaluate whether performing ultrasound to determine occiput position prior to performing an ID is associated with a reduction of failed fetal extraction procedures. Primary outcome is failed ID that will be compared between patients having ID preceded by US to ascertain fetal position and those having ID not preceded by US. Statistical analysis will include Propensity Score matching analysis as an analytical tool to assess the consequences that US use, in addition to clinical evaluation, has on the occurrence of ID failure. Recruitment is ongoing across 49 participating centres and the end of the enrolment is on May 31, 2025.