Fetal rotation during vacuum extractions for prolonged labor: a prospective cohort study

INTRODUCTION: The aim of the study was to investigate fetal head rotation during vacuum extraction. MATERIAL AND METHODS: We conducted a prospective cohort study from November 2013 to July 2016 in seven European hospitals. Fetal head position was determined with transabdominal or transperineal ultrasound and categorized as occiput anterior (OA), occiput transverse (OT) or occiput posterior (OP) position. Main outcome was the proportion of fetuses rotating during vacuum extraction. Secondary outcomes were conversion of delivery method, duration of vacuum extraction, umbilical artery pH <7.10 and agreement between clinical and ultrasound assessments. RESULTS: The study population comprised 165 women. During vacuum extraction 117/119 (98%) remained in OA and two fetuses rotated to OP position. Rotation from OT to OA position occurred in 14/19 (74%) and to OP position in 5/19 (26%). Rotation from OP to OA position occurred in 15/25 (60%), and 10/25 (40%) fetuses remained in OP position. Delivery information was missing in two cases. The conversion rate from vacuum extraction to cesarean section or forceps was 10% in the OA group vs. 23% in the non-OA group; p < 0.05. The estimated duration of vacuum extraction was significantly shorter in OA fetuses, 7 min vs. 10 min (log rank test p < 0.01). There was no significant difference in umbilical artery pH < 7.10 between OA and non-OA position. Cohens Kappa of agreement between clinical and ultrasound assessments was 0.42 (95% CI 0.26-0.57). CONCLUSION: Most fetuses in OP or OT positions rotated to OA position during vacuum extraction, but the proportion of failed vacuum extractions remained high

Occiput posterior position and intrapartum sonography

The occiput posterior position is reported to be the most common of all malpositions, and it may present as either straight (OP), left (LOP), or right (ROP). Diagnosis of OP position can be made at different times: during the third trimester, prior to the onset of labor, during the first stage of labor, while the fetus is transiting in the birth canal, and at birth. The time of diagnosis, though, is of different clinical significance, moving or not to a very specific management. Manual diagnosis of occiput posterior position either with abdominal palpation or vaginal examination is very subjective, prone to mistake, operator dependent, and made more difficult by caput and molding. Intrapartum ultrasonography has become a very reliable tool to hell the clinician to make a true diagnosis of malposition. The ultrasound probe may be used with different approach: transabdominal, suprapubical, transperineal, and transvaginal. The correct diagnosis of fetal head position as occiput posterior is imperative to be obtained in the management of any dystocia that may occur in the different stages of labor. Its knowledge will help the clinician to make the right decision at the right time, with the ultimate goal to reduce maternal and neonatal morbidity