Traces: making sense of urodynamics testing--Part 12: videourodynamics testing.
Key Words: Videourodynamics testing, urodynamics, radiographic images, lower urinary tract, physiologic tracings.
Videourodynamics testing combines radiographic images similar to those obtained during voiding cystourethrography with multichannel urodynamic traces showing pressure, flow, and electromyography (EMG). In contrast to complex urodynamics testing, whose history can be traced back to the early 20th century (Kraklau & Bloom, 1998), the origins of videourodynamics testing are more recent owing to the technologic demands of linking urodynamic tracings with radiographic images. Tanagho, Miller, Meyers, and Corbett (1966) described simultaneous observations of the response of the bladder neck during cystometric filling and voiding, including the phenomenon now described as bladder neck dyssynergia.
Combined multichannel urodynamics testing, including uroflowmetry, measurement of intravesical, abdominal and detrusor pressures, along with pelvic floor muscle electromyography (EMG) using a split screen technology and recorded on a videocassette, has been described in the literature (Bates & Corney, 1970; Bates, Whiteside, & Turner-Warwick, 1970). This technology is thought to have led to popularization of the currently used term for this technique, videourody namics (Webster & Older, 1980). Advances in technology, and especially in computer technology, now enable clinicians to link urodynamic traces with static and dynamic fluoroscopic imaging with much greater efficiency and resolution than the split-screen technology initially used for testing. This article describes videourodynamics testing techniques, and emphasis is placed on indications; techniques of testing; generation of clear, usable images while minimizing radiation exposure; and the interpretation of findings.
Indications for Videourodynamics Testing
Videourodynamics testing is usually performed when combined cystourethrography and multichannel urodynamics testing are likely to provide a diagnostic advantage to multichannel urodynamic tracings alone. Based on more than 30 years of clinical experience, I have found that videourodynamics testing is especially valuable in the following scenarios: 1) evaluation of neurogenic bladder dysfunction with urinary incontinence, incomplete bladder emptying, and/or a risk for upper urinary tract distress; 2) characterization of the level of obstruction in men or women; 3) assessment of selected women with a combination of stress urinary incontinence and lower urinary tract symptoms (LUTS) who are undergoing evaluation for initial or repeat surgical intervention; and 4) evaluation of selected men with urinary incontinence following radical prostatectomy, especially when complicated by urinary retention or when considering invasive surgery, such as implantation or revision of an artificial urinary sphincter or suburethral sling.
The American Urological Association (AUA) and the Society for Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (SUFU) have generated a clinical practice guideline for urodynamic testing in adults (AUA Education and Research, Inc., 2012). Based on systematic literature review, the guideline panel generated two statements pertaining to videourodynamics testing. The first recommends videourodynamics testing in patients with LUTS or elevated post-void residual volumes and neurologic conditions associated with possible neurogenic bladder dysfunction (AUA Education and Research, Inc., 2012). The strength of evidence supporting this statement is "C," indicating the statement is based on findings from observational studies that are inconsistent, have small sample sizes, or have other problems that might potentially confound interpretation of data. The second statement advises clinicians that videourodynamics testing may be performed in selected patients for localization of bladder outlet obstruction (AUA Education and Research, Inc., 2012). This statement is based on expert opinion of the clinical guideline panel, and it is strongly supported by clinical experience.
Techniques of Testing
Videourodynamics testing requires the clinician to apply knowledge and technical expertise to the generation of high quality multichannel urodynamic tracings and fluoroscopic imaging of the lower urinary tract. Parts 1 through 11 of the Traces series (published in Urologic Nursing) review techniques of multichannel testing in detail; this article focuses on techniques for generating high quality and clinically relevant fluoroscopic images of the lower urinary tract and interpretation of videourodynamic findings.
Voiding cystourethrography should be completed in close consultation with radiologic colleagues, including the radiologist, radiologic technologist, and/or radiation physicist. These individuals not only provide assistance with techniques for generating high quality radiographic images, they are also knowledge able about principles of radiation safety that minimize exposure to both patient and staff. Fluoroscopic images are typically generated via one of two platforms: a portable (C-arm) unit or a fixed unit (see Figures 1 and 2). Regardless of the type of unit used, the videourodynamic room must be inspected and deemed appropriate for radiographic imaging.
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Several federal agencies are primarily responsible for standards of radiation safety: the Nuclear Regulatory Commission, United States Environmental Protection Agency, and Departments of Energy and Transportation. However, radiation safety standards for clinical diagnostic facilities are regulated at the state level, and clinical radiation physicists have expertise in applying these standards to a specific videourodynamic laboratory (Nuclear Energy Institute, 2012). Safety precautions typically include lead-lined walls and other means of adequately shielding the immediate environment and personnel. Shielding professional staff in the videourodynamic laboratory includes use of a gown with no less than 0.25 mm lead-lining. The urodynamic clinician frequently moves around during testing; therefore, I recommend use of a lead-lined gown that either wraps around the trunk or has a front and back panel (see Figure 3). A thyroid shield and protective glasses are also recommended; prescription eyeglasses provide protection as well (International Atomic Energy Agency, 2012). The urodynamic clinician should consult the facility's radiology service and radiation safety professional, which is mandatory to ensure videourodynamic facilities function within these standards.
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Fluoroscopic images must be generated by a credentialed clinician, such as a radiologist or radiological technologist. Depending on state regulations and institutional policies, the urodynamic clinician may be credentialed to perform radiographic imaging for videourodynamics testing. As with all issues related to radiation safety, consultation with radiologic specialists in the facility is strongly recommended.
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Generating high quality videourodynamic images is technically challenging. The bladder and urethra are radiolucent, and generation of radiographic imaging requires infusion of contrast (McAlister & Griffith, 1983). Multiple cystographic contrast media are commercially available; we have found that 17.2% iothalamate or diatrizoate meglumine media are excellent for videourodynamic imaging. In addition to consulting with radiologic colleagues, the urodynamic clinician should consult with the equipment manufacturer when converting from saline or water-based filling cystometrograms to urodynamics testing using radiographic contrast media. Contrast media contain much higher concentrations of iodine bound salts than the sodium chloride in normal saline or trace amounts of solutes found in sterile water. The resulting fluid is comparatively viscous when compared to sterile water or saline. As a result, the urodynamic system must be adjusted to ensure that filling and voiding volumes are measured accurately. This typically requires adjustment of the uroflowmetry transducer and the estimated infused volume delivered by the pump during the filling cystometrogram (CMG). It is also important to remember that the comparatively small lumen of the 5to 7-French urodynamic catheters cannot effectively deliver contrast media when infused at higher fill rates; most manufacturers recommend fill rates of no more than 70 ml/minute for a 7-French urodynamic catheter and 50 ml/second for a 5-French urodynamic catheter. Based on my clinical experience, I recommend significantly slower fill rates of no more than 50 to 60 ml using a 7-French catheter and no more than 30 ml using a 5-French catheter (Gray, 2011b).
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Because the lower urinary tract lies at or below the symphysis pubis; imaging the bladder can create extreme difference in densities and low quality images (see Figure 4), especially when the patient is placed in an upright (sitting or standing) position. Several strategies may be employed to alleviate this phenomenon, including patient positioning, magnification of digital fluoroscopic images, and use of compensating filters. Completing the filling CMG while the patient is supine overcomes most of these technical challenges, but this position is avoided when possible during urodynamics testing because it does not reproduce LUTS as well as upright (sitting or standing) positions. Therefore, I recommend positioning the patient so the bladder base lies on the top one-half to one-third of the screen. This maneuver avoids centering the image on the center of the bladder where the largest mass of contrast lies. Using the fluoroscope's software to magnify the image may aid image quality by focusing on a smaller area of the bladder base and urethra. Compensating filters may be used to diminish contrast within the fluoroscopic image; some of these filters also reduce radiation exposure (Katsuda, Okazaki, & Kuroda, 1996). A number of compensating filtration devices are commercially available; they are typically wedge-shaped and attach to the collimator directly or attach via a magnet. Alternatives include placing a 1-liter bag of saline behind the patient's lower back. We use an aluminum wedge-shaped compensating filter that attaches snugly to the collimator of our fixed fluoroscopic unit; this device is custom-made by our radiographic department (see Figure 5).
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The patient is ideally placed in an upright (sitting) position on the micturition chair of the fixed unit fluoroscopic system or on a radiolucent urodynamic chair if a mobile fluoroscopic unit (C-arm) is used to generate images. The patient is positioned so the pelvis is oblique to the fluoroscopic collimator to visualize the entire urethral course during voiding or episodes of urinary leakage; anteroposterior positioning should be avoided because it creates superimposition of the proximal and distal urethra obscuring anatomic detail.
Common Images Obtained During Videourodynamics Testing
The number and type of fluoroscopic images are individualized based on the patient's lower urinary tract dysfunction and indications leading to videourodynamics testing. Nevertheless, the following images are commonly obtained during videourodynamics testing (see Table 1). A static image of the pelvis fulfills several purposes. It enables the radiographic technologist and urodynamic clinician to locate the symphysis pubis and supra-pubic area, and ensure the patient is positioned properly for generation of subsequent radiographic images. The preliminary image also enables identification of radiopaque structures in the pelvis area that may confuse interpretation of cystographic images, such as bony abnormalities of the pelvis, air or stool in the bowel, clips from previous surgical procedures, brachytherapy seeds in the prostate, ventriculoperitoneal shunt tubing, and phleboliths (see Figure 6). A preliminary film also enables the clinician to determine residual contrast from prior examinations, such as abdominal computerized tomography or barium-enhanced studies of the lower gastrointestinal tract. The preliminary film also allows identification of radiopaque bladder calculi.
After preliminary imaging, the filling cystometrogram is initiated, and the patient is instructed to report sensations of bladder filling (Gray, 2011a). A static image is often obtained at a low intravesical volume, usually 30 to 65 ml in adults and 10 to 30 ml in infants and children. This image enables identification of intravesical objects that may be obscured with additional filling. Examples include ureterocele, bladder stones not visualized on the preliminary image, or urothelial mass. Ureteroceles are most commonly seen in children and may contribute to bladder outlet obstruction and associated LUTS in selected children (Shokeir & Nijman, 2002).
Bladder calculi act as a nidus for bacterial colonization in the lower urinary tract and may increase the risk for symptomatic urinary tract infection. They are also associated with an increased risk for urothelial malignancy when present for a prolonged period of time (Papatsoris, Varkarakis, Dellis, & Deliveliotis, 2006). The presence of a bladder calculus should prompt consultation with the referring urologist or physician to determine whether to proceed with evaluation or whether to defer videourodynamics testing until vesical calculi are removed. The impact of bladder calculi on lower urinary tract dysfunction remains controversial; removal of bladder calculus may ameliorate or relieve mechanical obstruction caused by stones partially covering the bladder outlet during micturition. However, Millian-Rodriguez et al. (2004) compared urodynamic findings in 50 patients before and after vesicle stone ablation primarily via extracorporeal shock wave lithotripsy. While they found a high prevalence of lower urinary tract dysfunction, including bladder outlet obstruction in 51% and detrusor overactivity in 68%, removal of the stone did not significantly change urodynamic findings, raising the question of whether their presence should necessarily lead to discontinuation of evaluation prior to treatment. Nevertheless, bladder stones are associated with an increased risk for urinary tract infection, and the urodynamic clinician should consult with the referring provider concerning administration of prophylactic antibiotic treatment.
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Although rare, I have visualized several intravesical masses on low volume fluoroscopic images associated with urgency and urge incontinence. They ultimately proved to be urothelial tumors on subsequent endoscopy with biopsy. In each case, videourodynamics testing was discontinued, and the focus of treatment shifted to the management of the urothelial malignancy.
Identification of vesicoureteral reflux at lower volumes is usually associated with higher-grade reflux and more severe dysfunction of the ureterovesical junction as compared to lower grade reflux typically visualized at higher intravesical volumes. Identification of higher-grade vesicoureteral reflux is clinically relevant because it is associated with an increased likelihood of febrile urinary tract infection and reflux nephropathy and a reduced likelihood of spontaneous resolution (Altobelli, Buscarini, Nappo, Nguyen, & Caione, 2011; Hayn, Smaldone, Ost, & Docimo, 2008).
Although rare, the 5- to 7-French dual lumen catheter used with water-charged transducers or the 7-French air-charged transducer catheter may inadvertently enter a ureter during routine urodynamic instrumentation. In this case, the patient will complain of unilateral flank or low back pain, and the filling cystometrogram will show high amplitude but transient smooth muscle contraction as contrast enters the ureter. Should either of these events occur, fluoroscopic imaging enables the clinician to confirm the location of the catheter and enable the urodynamic clinician to reposition the catheter in the bladder vesical before proceeding with further testing.
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Fluoroscopic imaging of the bladder base and urethra at 200 ml is a critical component of videourodynamics testing in any woman undergoing videourodynamic evaluation of stress urinary incontinence with or without pelvic organ prolapse. Glancz, Cartwright, and Cardozo (2010) evaluated inter-rater reliability in a group of six urogynecologists when presented with dynamic videourodynamic images of women with stress, urge, or mixed urinary incontinence. Absolute inter-rater reliability of the presence and severity of stress incontinence was achieved in 75% and 81% of cases. Imaging includes visualization of the bladder base and urethra at rest and with abdominal straining. The clinician should observe for descent of the bladder base and urethrovesical junction, and entry of contrast into the urethra indicating a diagnosis of urodynamic stress urinary incontinence (see Figure 7). The presence of significant bladder base descent and a large cystocele may entirely obscure the bladder outlet in some women with higher-grade vaginal wall prolapse. In this case, a vaginal pack or pessary may be inserted and provocative maneuvers repeated to determine the presence of occult stress urinary incontinence (see Figure 8). A detailed description of the urodynamic evaluation of urethral sphincter competence is found in Part 7 of the Traces series (Gray, 2011b). Visualization of the bladder neck and urethra is also completed when evaluating selected men with urinary incontinence following radical prostatectomy.
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A fluoroscopic image may also be obtained to confirm the cause of urinary incontinence during the filling CMG. Routine imaging is not indicated when urine loss is clearly associated with detrusor overactivity. However, clinical experience strongly suggests that imaging is valuable in selected cases when the cause of urine loss is not apparent. In these cases, I have found that incontinence may be associated with more unusual etiologic factors including low bladder wall compliance and overflow incontinence, urinary fistulae, and unsuspected ectopic ureters in women.
Imaging of the full bladder is not routinely indicated, but it may provide clinically relevant information in selected patients. Examples include persons with vesicoureteral reflux at lower volumes, and patients with bladder diverticula or other anatomic defects likely to be influenced by intravesical volume. Imaging of a potential diverticulum is especially important because of its potential to dissipate energy form the intravesical space, affecting measurements of bladder wall compliance and detrusor contractility. The videourodynamic clinician should not only visualize the size and location of bladder diverticula; diagnosis should also include imaging the neck of the diverticulum to ensure it is not a pseudodiverticulum.
The voiding urethrogram is an essential component of any videourodynamic evaluation that includes a voiding pressure flow study, especially when evaluating the patient with bladder outlet obstruction. While routine multichannel urodynamics testing enables the clinician to identify and assess the severity of obstruction and the presence of vesicosphincter dyssynergia when pelvic floor EMG is assessed, videourodynamic imaging allows the clinician to localize the level of obstruction and the associated etiology. This information provides an invaluable guide to subsequent management. Figures 9 through 12 illustrate various levels of obstruction, including bladder neck dyssynergia, prostatic enlargement, and urethral stricture. The voiding urethrogram also provides an opportunity for the urodynamic clinician to diagnose a urethral diverticulum (Chang, Lin, & Chen, 2008). This diagnosis is especially important because this condition presents with a variety of clinical manifestations, including urgency, stress, urge or mixed urinary incontinence, and recurring urinary tract infection that may lead to videourodynamic testing when the patient fails to respond to initial treatment of these presenting symptoms.
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A post-void image provides important information not available with routine multichannel urodynamics testing. In addition to providing a visual estimate of the volume of post-void urine, it also allows the urodynamic clinician to complete a final visual inspection to identify vesicoureteral reflux, filling defects in the bladder base, or diverticula that were previously obscured behind intravesical contrast. The post-void film can also be used to help the clinician determine the renal contribution to cystometric capacity during the filling CMG (Gray, 2011c) and the need for subsequent catheterization when residual volumes are large.
Blending fluoroscopic images and multichannel urodynamic traces in selected patients allows a more comprehensive evaluation of lower urinary function than either modality completed alone. Videourodynamics testing is particularly useful for the evaluation of neurogenic bladder dysfunction with urinary incontinence and/or incomplete bladder emptying, identification of the level of bladder outlet obstruction, and assessment of lower urinary tract symptoms in selected patients undergoing evaluation for invasive surgical procedures.
Altobelli, E., Buscarini, M., Nappo, S.G., Nguyen, H.T., & Caione, P. (2011). Urodynamics investigation on children with vesicoureteral reflux identities overactive bladder and poor compliance in those with voiding dysfunction. Pediatric Surgery International, 27(5), 517-522.
American Urological Association Education and Research, Inc. (2012). Adult urodynamics: American Urological Association (AUA) and Society for Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (SUFU) guideline. Retrieved from http://www.auanet.org/content/media/adult_urodynamics_guide-line.pdf
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Mikel Gray, PhD, FNP, PNP, CUNP, CCCN, FAANP, FAAN, is a Professor and Nurse Practitioner, Department of Urology and School of Nursing, University of Virginia, Charlottesville, VA.
Note: Publication of this article is supported by a grant provided by LABORIE.
Table 1. Common Images Obtained During Videourodynamics Testing Image Purpose Preliminary image * Identification of radiopaque bladder calculi * Identification of radiopaque structures in the suprapubic area that may confuse interpretation of cystographic images such as phleboliths, bony abnormalities, clips from previous surgical procedures, brachytherapy seeds in the prostate, prosthetic devices, and ventriculoperitoneal shunt tubing Low volume bladder * Identify intravesical masses image visible only at low bladder volumes, such as ureterocele, urothelial masses * Identify higher grade vesicoureteral reflux occurring at lower intravesical (detrusor) pressures * Characterization of bladder neck as closed or funneled * Identification of bladder diverticula Dynamic images of * Assessment of bladder base bladder base and descent at rest and with urethra at 200 ml coughing or Valsalva's maneuver * Identification of bladder diverticula Dynamic images of * Characterization of bladder bladder base and base with leakage urethra with * Confirmation of urethral incontinence episodes leakage and measurement of during filling abdominal leak point pressure cystometrogram * Identification of vesicoureteral reflux Image of bladder and * Characterization of pelvis at cystometric bladder base capacity * Identification of Voiding urethrography vesicoureteral reflux, bladder diverticula * Characterization of urethral anatomy during voiding * Localization of level of obstruction * Confirmation of vesicosphincter dyssynergia observed on pelvic floor muscle electromyography Post-void image of * Estimation of post-void residual bladder * Identification of vesicoureteral reflux, bladder or suburethral diverticula immediately following micturition
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|Title Annotation:||Special Series on Urodynamics|
|Date:||Jul 1, 2012|
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