**2. Pelvic organ prolapse**

Pelvic organ prolapse (POP) is a prevalent condition affecting up to 50% of parous women; it most often presents with symptoms of urinary incontinence [8]. Traditionally, gynecologists identify prolapse by using a simple clinical staging system (stages 0 to III or IV), with 0 indicating normal conditions and III or IV denoting full organ prolapse or vaginal eversion fOP-Q staging for POP (POP-Q).

The accuracy of staging is important, as the treatment or surgery recommended to the patient is based on the staging of their POP. However, surgical repair of prolapse has a failure rate as high as 30%, and this is probably due to current pre-surgical evaluation providing incomplete assessment of the extent of the underlying structural changes causing the prolapse, resulting in incomplete repair. For instance, the levator ani muscle complex plays an important role in pelvic organ support. Evaluation of the integrity of this element of the pelvic structures is particularly difficult, and clinical examination alone is often insufficient [9].

Physicians assess patients using guidelines from organizations such as the International Urogynecological Association (IUGA) and International Continence Society (ICS) to evaluate women for POP and define treatment options to address the associated urinary and fecal incontinence.

The guidelines recommend steps for physical examination of symptomatic women which recognize that whether the patient is standing, sitting, or lying affects the position of the pelvic organs and the type, occurrence, and severity of symptoms. Hence, examination is done with the woman's bladder (and preferably rectum) empty, using the left lateral (Sims), or supine, standing, or lithotomy position, depending on which best demonstrates POP in that patient, and which the patient confirms is the maximal extent she has perceived. Forced expiration against a closed glottis (Valsalva) increases the accuracy of diagnosis CHANGE REFERENCE to a recent one/update the reference [10].

However, problematically, not all women can Valsalva effectively or tolerate examination when upright, and the guidelines acknowledge that "the more complicated the history and the more extensive and/or invasive the proposed therapy, the more complete the examination needs to be" [11]. Hence, further evaluation using imaging modalities is recommended when the appropriate indication(s) are present, with imaging highly recommended in specific situations. (IUGA) Imaging modalities employed currently include 2D and 3D ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI).

Current research on the association between childbirth-related pelvic floor muscle trauma and female POP provides an example of how imaging can aid better understanding of the pathophysiology of pelvic floor dysfunction [12–15], allowing primary (inflatable balloon device) [16] and secondary (surgical repair) prevention trials, and if all goes well resulting in efficient treatment based on translational research [17, 18].

Clinical examination focuses primarily on surface anatomy, which alone is not able to fully detect the extent of the underlying structural abnormalities. For example, prolapse of the posterior vagina, which is most prevalent in women with symptoms of prolapse and obstructed defecation is called "rectocele", and it occurs in at least five distinct anatomical forms that are hard to define without imaging [19]. Improved imaging of the pelvic floor to quantify and determine pelvic floor support has been identified as an important method to improve our understanding of POP, aid our ability to perform surgical repair, and to define the causes for surgical failure [20]. However, the position of the levator ani within the pelvic cavity, encircled as this structure is by the bony pelvis, and its shape, make direct imaging complex.

The differences between cystocele, enterocele, and rectocele are also difficult to determine with physical examination and are much better evaluated with imaging. Imaging also can discover unsuspected defects like enteroceles and sigmoidoceles [21]. The discovery rate of enteroceles is less with physical examination than with imaging; this is because of the misdiagnosis of enteroceles as rectoceles [22].

The role of imaging is to identify clinically suspected problems, discriminate between different anatomic defects, and define unsuspected problems in pelvic floor support. In patients with non-specific clinical findings, MRI can provide additional information to assess the need for surgical repair of the pelvic floor [21].
