Review ArticleA review of functional pelvic floor imaging modalities and their effectiveness
Introduction
Pelvic floor dysfunction affects approximately 15% of multiparous women [1]. This may lead to faecal incontinence, pelvic organ prolapse, and urinary incontinence with 10% of patients requiring surgery [2]. The pelvic floor, in conjunction with the bladder and anorectum, is responsible for the storage and expulsion of urine and stool, a function that requires coordination between the somatic external anal sphincter and visceral components such as the rectum and internal anal sphincter [3].
It is expected that, over the next 30 years, there will be a 45% increase in the demand for pelvic floor services, including imaging [2]. Current pelvic floor imaging techniques include ultrasound imaging, magnetic resonance imaging (MRI), and dynamic defaecating proctography or cystocolpodefaecography (DCP).
The support provided by the pelvic floor for the pelvic organs depends on the coordination of genital tract suspension by the endopelvic fascia and ligaments and the closure of the pelvic floor by the levator ani muscle [4]. Weakness of one component may be temporarily compensated for by action of the others, but this will increase the likelihood of occurrence of an eventual pelvic floor defect [5].
The endopelvic fascia (although it may be more accurately described as endopelvic connective tissue) refers to the tissue that forms a continuous sheet over the levator ani and pelvic organs, attaching to the bony pelvis [5]. Additional support of the urethra and bladder neck is provided by three condensations of this fascia—the periurethral, paraurethral, and pubourethral ligaments, with the pubourethral ligament acting as a fulcrum between the bladder and external urethral meatus [6]. The levator ani muscle, also known as the pelvic diaphragm, is subdivided into four muscles—pubococcygeus, iliococcygeus, coccygeus, and puborectalis, although the last can be considered a component of the external anal sphincter [3].
The female pelvis is divided into three compartments for the purposes of describing pelvic floor disorders [5], shown in Fig. 1 below.
The compartments and their associated disorders are further described in Table 1.
Pelvic floor dysfunction can also be caused by atrophy, previous injury to, or other weaknesses of levator ani, which can lead due global descent of the pelvic viscera due to loss of muscular support [5].
Section snippets
Imaging of the pelvic floor
Diagnosing pelvic floor pathology by physical examination alone has many shortcomings, including its tendency to focus on surface anatomy instead of structural abnormalities of the pelvic viscera [7]. As a result of this, imaging in conjunction with physical examination should be relied upon for the diagnosis, measurement, and treatment of pelvic floor defects.
Pelvic floor ultrasound
Various ultrasound techniques have been developed to image the pelvic floor, and these are able to visualise a range of pathological
Comparison of techniques
Of the three techniques, ultrasound is the cheapest. It is better tolerated than DCP in 87% of patients [33] and is able to identify suburethral slings (an advantage over MRI). In addition, 3D ultrasound can provide detailed information on the urethral complex, the bladder neck, and the superficial structures of the perineum [16]. Real-time 4D ultrasound scans allow further advantages over MRI when visualising prolapse, as it is easier to have the patient perform manoeuvres such as pelvic
Conclusion
Functional pelvic floor pathology results in a significant decrease in quality of life for women of all ages throughout the world, with urinary incontinence affecting between 17% and 45% of adult women [39]. Physical examination is now thought to be an increasingly unreliable method of diagnosis, as it produces results that are difficult to quantify and are also examiner dependent. Imaging techniques such as ultrasound, MRI, and DCP are increasingly important in assessment of the pelvic floor.
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