A Prospective Study on USS Assessment of Pelvic Structures in 3rd Trimester of Pregnancy Versus Delivery Outcome

The proposed study is to evaluate if there are specific factors in the pelvic floor functional anatomy which can predict the ability of having a vaginal birth after caesarean section.

Physical characteristics of the soft tissue in the female pelvis play an important role in successful vaginal delivery. A "tight" or less distensible pelvic floor muscles may influence mode of delivery, leading to poor labour progression and by compressing foetal head produce CTG abnormality such as decelerations, both resulting in caesarean delivery.

One of the main structures of the pelvic floor, the puborectoalis muscle, facilitates the passage of fetal head through the birth canal by stretching and distending. Therefore distensibility of the female pelvic floor influences mode of delivery.

Three hundred patients, in the third trimester of pregnancy, will be recruited via the antenatal clinics to minimize any disruption in their pregnancy care provision. Eligible participants are pregnant women who had either one or no vaginal births, or one caesarean section and who can give an informed consent and maintain their autonomy regarding mode of delivery with understanding of the forthcoming study results. Participants will be excluded if they sustain any obstetric complications that may impede on time and mode of delivery including an emergency prelabour caesarean section.

Ultrasonographic assessment of the differences in the pelvic characteristics of these women will be used to predict a successful of trial of vaginal delivery after caesarean section (VBAC) in subsequent pregnancies. The results will be used to better inform whether there is a simple (single ultrasound assessment) that can be used to help inform women's choice regarding mode of delivery.

Results from this research could be a pioneering blueprint for further studies, as there is very little known about this topic.