3D Transperineal Ultrasound Imaging of the changes of the pelvic floor muscles during labour

Vaginal delivery may cause denervation of the pelvic floor as well as direct
injury to muscles and connective tissue. These injuries may lead to the
development of stress urinary incontinence, faecal incontinence, voiding
difficulties, chronic obstipation and/or urogenital prolapse. Until now most
studies focused on anal sphincter rupture. Recently researchers have shown more
interest into injuries of the levator ani. Most authors assume that such
defects arise at the time of crowning of the fetal head1. However, proof for
this hypothesis has been lacking due to the inherent limitations of magnetic
resonance imaging and the logistic problems of performing MRI in young
asymptomatic nulliparous pregnant women in late gestation. Nowadays
3-dimensional and 4-dimensional pelvic floor ultrasound is capable of
demonstrating the pubovisceral muscle complex at little cost and with minimal
inconvenience to the patient.
The 3D ultrasound will enable us to examine what happens at which moment to the
pelvic floor during labour.

Primary Objective: 3D ultrasound imaging of the morphological changes of the
pelvic floor and the arising of possible defects during labour.

This study is designed as a pilot observational study and will be conducted in
the Erasmus Medical Centre. We will include ten healthy primimara women and
perform a 3-dimensional transperineal pelvic floor ultrasound once before
labour, two times during labour (3-5 cm dilation and 5-9 cm dilation), and
three times after labour (2-24 hours after delivery, 6 weeks after delivery, 3
months after delivery). By this means we will hopefully learn more about the
pelvic floor dynamics during labour, our special interest concerns the levator
ani.

We will perform six transperineal 3D ultrasound examinations in all subjects.
The first examinations will be performed before labour, the second and third
during labour. They will have no influence on the progress or timepath of
labour. There are no further risks for mother or child.
The first examination after labour will still take part in the delivery room
(2-24 hours after delivery). The ultrasound six weeks after delivery will be
combined with the general follow-up. There will be one extra appointment for
the examination three months after the delivery.