Pelvic floor ultrasound

Over the last 20 years, ultrasound has largely replaced radiological methods in the investigation of pelvic floor disorders. Transrectal, transvaginal/introital and transperineal/translabial methods have been investigated, with the transperincal/translabial approach currently the most widespread due to ease of use and the fact that equipment is available almost universally. Position and mobility of the bladder neck, bladder wall thickness, pelvic floor muscle activity and pelvic organ prolapse can be quantified, and Color Doppler may be used to document stress urinary incontinence. As a consequence, both preoperative assessment and audit activities in the field of pelvic reconstructive surgery have been markedly enhanced. This has been most evident in the evaluation of new synthetic slings and implants which usually are highly echogenic, making ultrasound the imaging method of choice for the evaluation of such grafts. Most recently, 3D translabial and transvaginal ultrasound have given access to the axial plane, allowing imaging of paravaginal spaces, the levator hiatus and the pubococcygeus/puborectalis muscles, i.e., the inferior aspects of the levator ani. The observation of manoeuvres such as a pelvic floor contraction or a Valsalva in the three orthogonal planes, rendered 3D volumes and 4D volume cine clips open up new possibilities for the assessment of functional anatomy, superior to what is currently possible with Magnetic Resonance Imaging. With the latest development, Volume Contrast Imaging (VCI), pelvic floor ultrasound has now reached the spatial resolution of MRI in all three dimensions, while providing far superior temporal resolution. It has become clear that, while there is a wide range of 'normality' in pelvic organ mobility and the dimensions of the levator ani and the hiatus itself, childbirth has a distinct effect on the dimensions of the hiatus and may cause significant soft-tissue trauma that is not apparent at the time of delivery. However, the clinical relevance of such traumatic changes remains to be determined. Much work will need to be done before the full potential of 3D/4D pelvic floor ultrasound is realized, both in research and in clinical practice.