Ultrasound during the second stage of labour: is it effective to reduce the caesarean section rates?

Abstract

The caesarean section is now the most frequent surgery performed on women at the reproductive age. It is known that caesarean section is associated with risks for the mother and baby, not only in the current pregnancy but also for future pregnancies. Taking into account these consequences and the rising trend of performing caesarean sections globally, strategies and recommendations have been formulated in some countries to decrease the need of a first caesarean section. This kind of surgery in the second stage of labor has been shown to be a contributing factor to the rise of caesarean section rates overall. In the second stage of labor, a vaginal delivery depends on a variety of factors. It is essential the assessment of the relation of the fetal head to structures of the maternal pelvis and the ability to predict a successful outcome, especially when an operative vaginal delivery is contemplated. We know that an ordinary clinical examination is subjective and not accurate; therefore, this subjectivity can lead to an incorrect decision about the mode of delivery. Furthermore, there is a rising trend in caesarean section at full dilatation, which may be due to insecurity on the clinical examination findings and a lack of confidence in achieving a vaginal delivery outcome. The use of intrapartum transabdominal and translabial ultrasound has been shown to objectively assess the relationship between the fetal head and maternal pelvis and can indeed predict the likelihood of achieving a vaginal delivery. This fact solves two problems; firstly, it removes the subjectivity from the clinical assessment and secondly, it can improve clinical confidence, especially when an attempt at operative vaginal delivery is wanted. The fetal head position can firstly be readily assessed transabdominally by locating the fetal spine and the occiput, located at 180° to the spine. Above the symphysis pubis, visualization of the fetal orbits can positively confirm an occiput posterior position. A transverse midline echo of the corpus callosum identifies an occiput transverse position. These basic assessments are crucial in the diagnosis of the overall lie of the fetus and the orientation of the fetal head to the spine. These aspects are important when a rotation element may be required to deliver the baby, which will determine the rotation direction to be performed. Studies have shown that these techniques can be easily taught and applied and may even be more reliable than the clinical exam.