Ultrasound markers associated with persistent occiput posterior position and mode of delivery: a systematic review

To systematically evaluate evidence on intrapartum ultrasound markers, deflexion, spine position, asynclitism, and angle of progression (AoP), and their associations with spontaneous rotation and delivery outcomes in foetuses with occiput posterior (OP) position.

A systematic search of Cochrane, Scopus, PubMed, and Ovid/MEDLINE was conducted using MeSH terms and keywords. Eligible studies included intrapartum ultrasound assessment of foetal position with at least one additional sonographic marker and reported outcomes related to rotation or mode of delivery. Data on study design, population characteristics, ultrasound methods, and outcomes were extracted. Of 543 records identified, 13 studies (predominantly prospective cohorts) published between 2010 and 2023 met inclusion criteria and were critically appraised.

Foetal head deflexion and posterior spine position were most consistently associated with persistence of OP and higher operative delivery rates. Evidence for asynclitism and AoP was limited and inconsistent. Small sample sizes, heterogeneous study populations, variable ultrasound timing, and inconsistent reporting limited comparability across studies.

Intrapartum ultrasound markers, particularly deflexion and spine position, are associated with persistent OP, but current evidence is constrained by methodological heterogeneity and underpowered cohorts. Standardised definitions and larger, well-designed studies are required before these markers can be integrated into routine clinical assessment.