**4. Current imaging techniques**

Evaluation using imaging modalities is recommended in international guidelines when the appropriate indication(s) are present, and imaging is highly recommended in specific situations [10]. Imaging modalities employed currently include 2D and 3D ultrasound, computed tomography, and magnetic resonance imaging.

## **4.1. Ultrasound**

the supine position with patients lying in a closed-configuration MR scanner [23]. The principal reason for this is the limitation on imaging to the supine position. Lying supine is also comfortable for most patients, and this technique has been simple to standardize. However, in POP, posture and gravity impact pelvic organ position, pelvic floor muscle integrity, degree of prolapse, and symptom severity. Indeed, the degree of prolapse may be worse after a lengthy time in the upright position and better when gravity is not a factor, e.g., when lying in the supine position [10]. Hence, one could question if measurement in the lying position is valid for assessment of muscle function or the evaluation of patients who are symptomatic in the standing position [24]. Additionally, gravity and body weight contribute to pelvic organ muscle contractile features when standing [25]. It is likely that complex factors related to upright posture that produce more contractility over pre-loaded and/or pre-activated muscles come into play, as the weight of pelvic organs and gravity are contributing forces affecting the pelvic floor. This may explain why digital muscle testing and squeeze-pressure readings can be lower in the standing position. However, it is not known exactly which components of pelvic organ muscle activation

Hypothetically speaking, the dynamics of the whole pelvic floor may be modified (or the squeeze and the elevation components might be influenced variously) owing to different effects such as descent of the pelvic organs when standing, different tensions on fascia and ligaments, alteration in resting length and tone of the contractile elements, and other factors. It is well known that being upright results in a displacement of the pelvic organs and the pelvic organs muscle as compared with being supine [24, 26]. The full bladder is less mobile than the empty organ this factor may prohibit complete pelvic organ prolapse. In the standing orientation, the bladder is situated lower at rest but descends about as far in a lying patient on a Valsalva maneuver [27]. Dietz and Clarke [27] in their population of 132 patients with pelvic floor dysfunction found a 5-mm difference in the resting level of the bladder neck between supine and standing as measured by transperineal ultrasound. The only study comparing MRI in sitting and lying positions found that they were equally efficient in recognizing clini-

The position and eventual prolapse of pelvic organs is best visualized on MRI in the midsagittal plane. The imaging technique for the pelvic floor involves imaging several pelvic floor positions. Firstly, the position of the pelvic organs is assessed at rest. Then, the pelvic floor muscles images are recorded during squeezing to view the contractility and the strength of contraction of the pelvic floor. In the third phase, pelvic floor pathologies are assessed during straining and evacuation. In a recent study to view the full extent of pelvic floor pathologies, imaging was done during evacuation of a contrast agent; a number of pathologic conditions

would have been missed if these defecation phase images had not been acquired [29].

Evaluation using imaging modalities is recommended in international guidelines when the appropriate indication(s) are present, and imaging is highly recommended in specific

— squeeze or lift — are influenced by alterations in posture.

22 Pelvic Floor Disorders

cally relevant problems of the pelvic floor [28].

**4. Current imaging techniques**

Imaging the pelvic floor in cases of dysfunction dates back to the 1920s [2]. Radiological techniques were used first to show changes in the bladder's location within the pelvis and subsequently to demonstrate central and posterior compartment prolapse. During the 1980s the advent of B-mode real-time ultrasound allowed a clear image to be obtained by the transperineal or the vaginal route [19].

Translabial ultrasound can define uterovaginal prolapse [30]. The inferior border of the symphysis pubis works as a line of reference against which the higher descent of bladder, uterus, culde sac, and rectal ampulla on Valsalva maneuver can be measured [30]. Ultrasound imaging for prolapse quantification is especially helpful in outcome evaluation after pelvic reconstructive surgery, both clinically and in a research context, and it has also led to a re-appraisal of what is meant by prolapse.

The structures used for evaluation of the three compartments are (a) the bladder neck or the leading edge of a cystocele for the anterior vaginal wall, (b) the cervix (or, within certain limitations, the pouch of Douglas) for the central compartment, and (c) the rectal ampulla for the posterior compartment. All these structures are imaged in real time in the mid-sagittal plane. An exception is a high undescended uterus that may be hidden by a rectocele [10]. Because of its non-invasive nature, ready availability, and lack of distortion, perineal or translabial ultrasound is now commonly applied in clinical practice [30], and almost all gynecologists and urologists are trained in its use [19].

Current developments such as the evaluation of levator ani muscle activity and prolapse and the use of color Doppler to define urine leakage are further promoting the clinical utility of ultrasound. Hopefully, improved standardization of parameters will facilitate the ability of clinicians and researchers to compare data [30].

Regardless of which technique is used to define descent of the pelvic organs, it is obvious that there is a large difference in pelvic organ mobility even in young nulliparous women. This difference may be partially genetic in origin. Ultrasound imaging permits quantification of the wide variation in pelvic organ mobility, which will make it easier to use molecular and population genetic approaches to assess the etiology of pelvic floor and bladder dysfunction [30].

It seems to be irrelevant with chapter title Ultrasound imaging of the pelvic floor is safer, lower in cost, and better at providing visualization of the pelvic floor structures in real time than MRI. This includes evaluation of levator function and dynamic changes during contraction and Valsalva [20]. As yet, there are no comparisons of pre- and postnatal results gained with MRI, possibly because of cost and logistic problems. However, such a comparison is available for many hundreds of women studied by 4D translabial ultrasound [2].

Disadvantages of ultrasound include that a large bowel-filled prolapse, i.e., an enterocele or rectocele, may cause incomplete imaging of the cervix and vault if these structures remain high. In addition, variable transducer pressure can result in an underestimation of severe prolapse. Procidentia or complete vaginal eversion prevents translabial imaging, and sometimes what appears to be anterior vaginal wall prolapse will turn out to be due to a urethral diverticulum [31, 32].

straining and evacuation. In a recent study to view the full extent of pelvic floor pathologies imaging was done during evacuation of a contrast agent; a number of pathologic conditions

Effects of Posture and Gravity on Pelvic Organ Prolapse http://dx.doi.org/10.5772/intechopen.77040 25

Dynamic MRI techniques have been shown to be more sensitive than pelvic examination in evaluating and grading pelvic floor displacement in supine women and also for diagnosis of rectoceles [35, 42]. In the case of an anorectal problem, MR defecography can identify several components of pelvic floor dysfunction, including rectal descent, enterocele, anterior procto-

The short acquisition time is relevant because patients do not need to keep on straining for more than 1 to 3 s. Patients are instructed in the Valsalva maneuver before the start of the examination, and instructions are repeated frequently during the imaging sequence [37, 38]. Dynamic sequences that permit the acquisition of images in 1 to 10 s are helpful to obtain

Sometimes, patients cannot tolerate MRI due to claustrophobia, general weakness, or the presence of medical equipment [33]. Positive elements of MRI include the fact that filling the bladder, the vagina, or the rectum does not seem to be a fundamental requirement because of to the high resolution of MRI, which prevents distorting the anatomy of the pelvic organs [40].

The expense of MRI imaging and limited access to scanning facilities has impacted widespread application of this technology. Additionally, because of the dynamic nature of pelvic floor pathology, it is controversial whether even fast MRI imaging can capture reproducible results owing to the dissimilarity of Valsalva maneuvers between studies and possible varia-

The physical features of MRI systems make it complicated for the operator to ensure efficient conduct of the required maneuvers by patients; over 50% of women do not achieve a proper pelvic floor contraction during examination, and a Valsalva is very often confounded by associated levator ani activation [41]. Without real-time imaging, these confounders cannot be

Importantly this provides the ability to replicate normal functional posture and enables the effects of gravity on prolapse to be evaluated for the first time [7]. In POP, posture and gravity impact pelvic organ position, pelvic floor muscle integrity, degree of prolapse, and symptom severity, and the degree of prolapse may be worse after time in the upright position and better when gravity is not a factor, e.g., when lying in the supine position [1]. Near-real-time sequences allow images to be obtained every 1.5 s. These can be stored and displayed on video, enabling a dynamic assessment of the pelvic floor from the resting position through straining and contraction [40]. The gynecologic literature proposes that straining in the lying position does not give sufficient deformity of the pelvic floor for accurate delineation of prolapse.

Upright open MRI allows visualization of all the pelvic organs and the pelvic floor support structures; obviously the technique combines the advance of allowing sitting and standing imaging with the known benefits of conventional MRI. We believe that the importance of this

Also, in a research context, MRI is acceptable to asymptomatic volunteers [40].

would have been missed if these defecation phase images had not been acquired [29].

cele, and internal rectal prolapse [36].

maximal strain [39].

tions in levator activity [10].

controlled for [2] upright open MRI.

#### **4.2. CT scan**

CT is not usually recommended for imaging the pelvic floor because of the level of radiation required. However, this modality can offer accurate visualization of the pelvic soft tissue and bony structures and has been used to increase the diagnostic accuracy of pelvic floor anatomical disorders [1]. Although the soft tissue contrast with CT is inferior to that of MRI, the bladder, uterus, small bowel, peritoneal fat, and rectum are readily identified, and changes in position with the patient straining can be visualized. Additionally, the contour of the levator ani muscles can be evaluated effectively, and images of pelvic anatomy can be produced in multiple planes. Therefore, in patients who cannot tolerate MRI and in whom rapid noninvasive multiplanar assessment of the pelvis is desired, CT has a potential role. With recent scanners, tube output can be modified depending on the patient's body thickness, and this may help to decrease the radiation dose given. The pelvic floor and viscera can be visualized, and the addition of dynamic imaging can be applied to determine prolapse [33].

#### **4.3. MRI**

Techniques associated with urology have developed over the last 30 years. In the 1990s MR techniques were improved with rapid and strong gradients and higher readout bandwidth. The first study depicting the using of MR for imaging pelvic organ prolapse was by Yang et al.

The increasing availability of MRI has added the benefit of this form of diagnostic imaging to evaluation in urogynecology and female urology, with more studies being done every year [30]. With the option of cross-sectional imaging methods, MRI has emerged as an alternate method to fluoroscopy for assessing patients with pelvic organ prolapse [34].

Benefits of MRI include multiplanar imaging and superior soft tissue contrast, permitting evaluation of the pelvic floor levator ani muscle in detail. The anatomy of the levator ani is now known to be complex; it has been shown not to be a single muscle, being composed of two functional components that differ in thickness and function [20]. In addition, where there is organ prolapse, enhanced visualization of the rectovaginal space improves diagnosis of peritoneoceles and enteroceles and of the cervix clarifies cervical descent [33]. This allows demonstration of enterocele-type defects or peritoneoceles where there is just herniation of peritoneal fat and not bowel, comprehensive evaluation of the levator ani muscle, and visualization of the uterus.

The position and relationship of the pelvic organs are best visualized on MRI in the midsagittal plane. The imaging technique for the pelvic floor involves imaging in various pelvic floor positions. Firstly, the position of the pelvic organs is assessed at rest. Then, the pelvic floor muscles images are recorded during squeezing to view the contractility and the strength of contraction of the pelvic floor. In the third phase, pelvic floor pathologies are assessed during straining and evacuation. In a recent study to view the full extent of pelvic floor pathologies imaging was done during evacuation of a contrast agent; a number of pathologic conditions would have been missed if these defecation phase images had not been acquired [29].

high. In addition, variable transducer pressure can result in an underestimation of severe prolapse. Procidentia or complete vaginal eversion prevents translabial imaging, and sometimes what appears to be anterior vaginal wall prolapse will turn out to be due to a urethral

CT is not usually recommended for imaging the pelvic floor because of the level of radiation required. However, this modality can offer accurate visualization of the pelvic soft tissue and bony structures and has been used to increase the diagnostic accuracy of pelvic floor anatomical disorders [1]. Although the soft tissue contrast with CT is inferior to that of MRI, the bladder, uterus, small bowel, peritoneal fat, and rectum are readily identified, and changes in position with the patient straining can be visualized. Additionally, the contour of the levator ani muscles can be evaluated effectively, and images of pelvic anatomy can be produced in multiple planes. Therefore, in patients who cannot tolerate MRI and in whom rapid noninvasive multiplanar assessment of the pelvis is desired, CT has a potential role. With recent scanners, tube output can be modified depending on the patient's body thickness, and this may help to decrease the radiation dose given. The pelvic floor and viscera can be visualized, and

Techniques associated with urology have developed over the last 30 years. In the 1990s MR techniques were improved with rapid and strong gradients and higher readout bandwidth. The first study depicting the using of MR for imaging pelvic organ prolapse was by Yang et al. The increasing availability of MRI has added the benefit of this form of diagnostic imaging to evaluation in urogynecology and female urology, with more studies being done every year [30]. With the option of cross-sectional imaging methods, MRI has emerged as an alternate

Benefits of MRI include multiplanar imaging and superior soft tissue contrast, permitting evaluation of the pelvic floor levator ani muscle in detail. The anatomy of the levator ani is now known to be complex; it has been shown not to be a single muscle, being composed of two functional components that differ in thickness and function [20]. In addition, where there is organ prolapse, enhanced visualization of the rectovaginal space improves diagnosis of peritoneoceles and enteroceles and of the cervix clarifies cervical descent [33]. This allows demonstration of enterocele-type defects or peritoneoceles where there is just herniation of peritoneal fat and not bowel, comprehensive evaluation of the levator ani muscle, and visu-

The position and relationship of the pelvic organs are best visualized on MRI in the midsagittal plane. The imaging technique for the pelvic floor involves imaging in various pelvic floor positions. Firstly, the position of the pelvic organs is assessed at rest. Then, the pelvic floor muscles images are recorded during squeezing to view the contractility and the strength of contraction of the pelvic floor. In the third phase, pelvic floor pathologies are assessed during

the addition of dynamic imaging can be applied to determine prolapse [33].

method to fluoroscopy for assessing patients with pelvic organ prolapse [34].

diverticulum [31, 32].

**4.2. CT scan**

24 Pelvic Floor Disorders

**4.3. MRI**

alization of the uterus.

Dynamic MRI techniques have been shown to be more sensitive than pelvic examination in evaluating and grading pelvic floor displacement in supine women and also for diagnosis of rectoceles [35, 42]. In the case of an anorectal problem, MR defecography can identify several components of pelvic floor dysfunction, including rectal descent, enterocele, anterior proctocele, and internal rectal prolapse [36].

The short acquisition time is relevant because patients do not need to keep on straining for more than 1 to 3 s. Patients are instructed in the Valsalva maneuver before the start of the examination, and instructions are repeated frequently during the imaging sequence [37, 38]. Dynamic sequences that permit the acquisition of images in 1 to 10 s are helpful to obtain maximal strain [39].

Sometimes, patients cannot tolerate MRI due to claustrophobia, general weakness, or the presence of medical equipment [33]. Positive elements of MRI include the fact that filling the bladder, the vagina, or the rectum does not seem to be a fundamental requirement because of to the high resolution of MRI, which prevents distorting the anatomy of the pelvic organs [40]. Also, in a research context, MRI is acceptable to asymptomatic volunteers [40].

The expense of MRI imaging and limited access to scanning facilities has impacted widespread application of this technology. Additionally, because of the dynamic nature of pelvic floor pathology, it is controversial whether even fast MRI imaging can capture reproducible results owing to the dissimilarity of Valsalva maneuvers between studies and possible variations in levator activity [10].

The physical features of MRI systems make it complicated for the operator to ensure efficient conduct of the required maneuvers by patients; over 50% of women do not achieve a proper pelvic floor contraction during examination, and a Valsalva is very often confounded by associated levator ani activation [41]. Without real-time imaging, these confounders cannot be controlled for [2] upright open MRI.

Importantly this provides the ability to replicate normal functional posture and enables the effects of gravity on prolapse to be evaluated for the first time [7]. In POP, posture and gravity impact pelvic organ position, pelvic floor muscle integrity, degree of prolapse, and symptom severity, and the degree of prolapse may be worse after time in the upright position and better when gravity is not a factor, e.g., when lying in the supine position [1]. Near-real-time sequences allow images to be obtained every 1.5 s. These can be stored and displayed on video, enabling a dynamic assessment of the pelvic floor from the resting position through straining and contraction [40]. The gynecologic literature proposes that straining in the lying position does not give sufficient deformity of the pelvic floor for accurate delineation of prolapse.

Upright open MRI allows visualization of all the pelvic organs and the pelvic floor support structures; obviously the technique combines the advance of allowing sitting and standing imaging with the known benefits of conventional MRI. We believe that the importance of this technique is that it enables comprehensive definition of the full extent of organ prolapse due to the effects of posture and gravity [40].

However, different criteria are currently used for diagnosing prolapse on MRI. Most research that reported using the bony reference lines uses one of the following criteria: (a) descent of the bladder base more than 1 cm inferior to the pubococcygeal line, (b) position of the cervix or vaginal vault less than 1 cm over the PCL or below it, and (c) descent of the posterior compartment more than 2.5 cm below the PCL (International Urogynecological Association and International Continence Society) [1]. There are also other minor differences in the diagnostic criteria applied for prolapse; cystocele has been defined as when the bladder descends to any area below the PCL, and uterocervical prolapse and enterocele are when the cervix or small bowel are below the PCL .

Effects of Posture and Gravity on Pelvic Organ Prolapse http://dx.doi.org/10.5772/intechopen.77040 27

Based on our literature search research, the protocol we propose for upright open MRI evaluation of women with prolapse and stress urinary incontinence is as follows. (1) All women complete a history that includes validated symptom scores for bladder, bowel, and prolapserelated symptoms. (2) Patients have a physical examination that follows IUGA/ICS guidelines [10]; this examination includes POPQ staging. (3) Patients complete a screening assessment tool to ensure there are no contraindications for magnetic resonance imaging. Some metals and surgical hardware are ferromagnetic and, therefore, are not acceptable with MRI. (4).

Our images are obtained currently using a 0.5 T scanner located at a dedicated research facility at the Centre for Hip Health at the University of British Columbia, Canada. Each patient's preparation includes ensuring a full bladder; hence, they are asked to refrain from voiding for 2 h before imaging. For standing images, intermittent pneumatic compression devices are applied to the legs. A T2-weighted sagittal image of the midline structures, including the symphysis, urethra, and coccyx, is acquired. Women then empty the bladder, and images in the supine, seated, and upright position are obtained. Current settings based on pilot studies indicate successful imaging is obtained with the following: TR/effective TE, 2500/16; echo train length, 32; bandwidth, 32 kHz; excitation, one; matrix size, 256 × 160; field of view, 0.5 (24 cm); section thickness, 5 mm, slice gap, 1. Sagittal images for mobility of the bladder neck

As an example of the benefits of this protocol, a 60-year-old multiparous woman presented with increasing urinary incontinence, constipation, a sensation of incomplete emptying, pelvic pressure, and pain. On pelvic examination (supine and inclined, at rest, and with Valsalva), no organ descent was detected. Conventional supine magnetic resonance imaging (MRI) did not identify pelvic organ prolapse (POP), but evaluation using upright open MRI diagnosed that organ prolapse involving the bladder occurred when standing. In **Figure 1** an example of anterior views of sagittal images showing gravity-induced quantification prolapse can be

**6. Proposed protocol for upright open MRI evaluation of POP**

Imaging is then conducted.

and urethra can be obtained during straining [46].

**7. Proposed clinical scenario for imaging**

Upright open MRI is currently only available as a research entity. A new clinical protocol for MRO image capture of the female pelvis has been created and introduced into clinical practice. This provides enhanced anatomic definition and allows more comprehensive evaluation and staging.
