Intrapartum ultrasound for fetal head asynclitism: Is it possible to establish a degree of asynclitism to correlate to delivery outcome?

ABSTRACT

OBJECTIVE: To investigate the role of intrapartum ultrasound (IU) in the diagnosis of asynclitism and the importance of asynclitism degree in labor outcomes. METHOD: This prospective cohort study included 41 low-risk pregnant women with fetus in singleton-vertex. The IU assessment to diagnose asynclitism was performed during labor at two specific steps, including the suspicion and/or diagnosis of labor arrest. The "four-chamber view" and "squint sign without nose" were classified as marked/severe asynclitism. The "midline deviation" and "squint sign with nose" findings were classified as moderate asynclitism. Obstetric outcomes and maternal-fetal complications were compared with the degree of asynclitism. RESULTS: Severe and moderate asynclitism was seen in 17 (41.7%), 10 (58.8%) and seven (41.2%) women, respectively. All pregnant women diagnosed with asynclitism delivered by vacuum extraction (VE) or cesarean section (CS). CS was performed in nine patients with asynclitism (52.9%). The difference between asynclitism type and VE/CS ratios was statistically significant (P = 0.039). Four fetuses with squint sign without nose delivered by VE. A significant correlation was seen between the presence of squint without nose sign and second-/third-degree perineal injury. CONCLUSION: Severe asynclitism is associated with increasing operative birth and maternal-fetal complications. Detection of asynclitism degree by IU could be useful, alerting the obstetrics team to possible perinatal problems during delivery.