Objective: To evaluate the value of intrapartum ultrasonographically determined occiput position and risk of cesarean section.
Material and Method: Between August 1, 2008 and May 31, 2009, 330 singleton pregnant women, GA 37-42 weeks with cephalic presentation who were in early active phase of labor at Thammasat University hospital were recruited. The fetal occiput position was determined by transabdominal ultrasonography. The occiput posterior defined as cases and non-occiput posterior defined as controls. Perinatal outcomes and delivery methods were recorded. Independent sample t-test, Chi-square and multivariable regression were applied for analysis.
Results: The incidence of occiput posterior was 29.7%. The abnormal cervical dilatation, cesarean delivery, and newborn weight were statistically significantly higher in cases. 44.9% of cases underwent cesarean section compared to 14.7% of controls.
Conclusion: Fetal occiput posterior presentation determined in early stage of active labor by ultrasonography was a significant independent risk of cesarean section.

Keyword : Fetal occiput position, Occiput posterior, Intrapartum ultrasonogram, Cesarean section