Randomised Italian Sonography for occiput POSition Trial Ante vacuum (R.I.S.POS.T.A.)

Area of Science:

• Obstetrics and Gynecology
• Medical Imaging
• Clinical Trials

Background:

• Instrumental vaginal delivery, particularly vacuum extraction, is common for fetal malposition.
• Accurate assessment of fetal head position is crucial for successful instrumental delivery.
• Sonography offers a potential tool to improve diagnostic accuracy over traditional vaginal examination.

Purpose of the Study:

• To evaluate if sonographic diagnosis of fetal head position improves outcomes during instrumental vaginal delivery.
• To determine if ultrasound reduces the rate of failed vacuum extractions and subsequent emergency Cesarean sections.
• To assess the impact of sonographic guidance on maternal and fetal morbidity.

Main Methods:

• A randomized controlled trial (R.I.S.POS.T.A.) involving 221 women undergoing vacuum extraction for cephalic presentation.
• Participants were randomized to fetal head position assessment by vaginal examination (VE) alone or VE plus transabdominal sonography (TAS).
• The primary outcome was the incidence of emergency Cesarean section due to failed vacuum extraction.

Main Results:

• The trial was stopped early for futility.
• No significant differences were found in emergency Cesarean sections or other maternal/fetal outcomes between the VE and VE plus TAS groups.
• While TAS improved diagnostic accuracy of fetal head position, it led to a higher rate of episiotomy.

Conclusions:

• Sonographic assessment of fetal head position prior to vacuum extraction did not demonstrate a benefit in reducing failed instrumental deliveries.
• The study did not find improvements in maternal or fetal morbidity with the addition of sonography.
• Premature discontinuation limited definitive conclusions, but current evidence suggests no clear advantage for routine sonographic use in this context.