Endoscopic assessment of the lower urinary tract

Historical perspective

The first endoscopic technique for evaluating the female urethra and bladder was described by Bozzini in 1805 and used candlelight reflected through a funnel in the urethra. Nineteenth-century refinements to this crude instrument included a surrounding cannula and, later, a lens system to provide magnification of the field of view. Despite efforts to improve illumination using reflective mirrors, an alcohol lamp, a platinum wire loop, and, finally, an incandescent light source, visualization remained poor without bladder distention. Consequently, by the end of the nineteenth century, cystoscopy was merely an adjunct to the established practice of urethral dilation and bimanual palpation of the bladder.

changed the role of cystoscopy by developing an innovative technique that provided adequate bladder distention. The cystoscope, essentially a hollow tube without a lens, was introduced, using an obturator with the patient in the knee-chest position. The negative intraabdominal pressure created in this position allowed air to distend the bladder when the cystoscope was introduced. A head mirror was used to reflect an electric light into the bladder for illumination. This simple technique dramatically enhanced the accessibility of cystoscopy to all physicians.

The twentieth century saw many innovations in cystoscopy. introduced a fiberoptic telescope and, later, a rod lens system, which dramatically improved light transmission and resolution. Their rod lens design is the system used in today’s rigid cystoscopes. Replacement of the air chamber with a series of glass rods with optically finished ends, separated by intervening air spaces, provides a wider viewing field and permits a change in the viewing angle. The innovation of angled telescopes improved the extent of visualization and facilitated more invasive and operative procedures, largely used during this time in the new subspecialty of urology.

, known as the American “father of urogynecology,” reintroduced cystoscopy to the field of gynecology with his Robertson urethroscope. This instrument addressed the deficiencies of the cystoscope for viewing the urethra by applying the rod lens technology of the Hopkins cystoscope to a shorter straight-on telescope with a nonfenestrated sheath designed specifically for viewing the urethra. He also outlined a technique, dynamic urethroscopy, for evaluating incontinent women. Dynamic urethroscopy offered a simple office procedure that considerably improved the clinical evaluation of the lower urinary tract of the time.

The most recent development in cystoscopy is the flexible cystoscope. A flexible cystoscope takes advantage of the flexibility of the fiberoptic lens system to create a cystoscope that bends, thereby increasing the range of the field of view. Some authors report an improved view of the bladder neck using a flexible fiber cystoscope, whereas others advocate flexible cystoscopy to limit the necessary instrumentation and improve patient tolerance.

Indications

Cystourethroscopy is an indispensable procedure for today’s urogynecologist, with both diagnostic and operative indications. Diagnostic indications include hematuria, lower urinary tract symptoms, urinary incontinence, urethral diverticula, and urogenital fistulas.

The differential diagnosis of hematuria is extensive but includes conditions that are primarily renal or postrenal in origin. Endoscopy is useful in the diagnosis of postrenal conditions, including neoplasms of the bladder and urethra, urethral polyps, chronic cystitis, recurrent cystitis, interstitial cystitis, urolithiasis, and foreign bodies.

The differential diagnosis for lower urinary tract symptoms is extensive, including many nebulous conditions. Possible causes include acute cystitis, chronic cystitis, radiation cystitis, urethral pain syndrome, urethral diverticula, urethritis, and interstitial cystitis. Other conditions that may cause similar symptoms include detrusor overactivity, urolithiasis, suture or mesh in the bladder or urethra, partial urinary retention, and moderate to severe pelvic organ prolapse. Cystourethroscopy is indicated when the presenting symptoms strongly suggest a diagnosis of urethral diverticulum, interstitial cystitis, urolithiasis, foreign body, or tumor, as well as for patients who do not respond to initial therapy. Endoscopy should be avoided in the presence of an active urinary tract infection.

There is general agreement that cystoscopy is indicated for patients complaining of persistent incontinence or voiding symptoms following incontinence surgery, but there is less agreement about the role of cystoscopy in the baseline evaluation of patients with urinary incontinence. The refinement of urodynamic evaluation since the 1980s has demonstrated its superiority for diagnosing the common causes of urinary incontinence such as urodynamic stress incontinence and detrusor overactivity. However, urodynamic testing provides little information about lower urinary tract anatomy, which can be achieved with urethrocystoscopy. Anatomic abnormalities, such as urethral diverticula, urogenital fistulas, and intravesical foreign bodies causing detrusor overactivity, might be suspected based on history or urodynamic tests but require an anatomic assessment for confirmation. Cystourethroscopy also can reveal unsuspected neoplasia in the incontinent patient.

Cystourethroscopy also has value in the diagnosis of intrinsic sphincter deficiency, which has no standardized diagnostic criteria. Some advocate a single urodynamic parameter to make the diagnosis, such as leak point pressure or urethral pressure profilometry. In the absence of validated standard criteria for diagnosing intrinsic sphincter deficiency, we advocate combining clinical measures of severity, urodynamic evidence of poor urethral resistance, and an anatomic evaluation of urethral coaptation. Cystourethroscopy is perhaps the simplest way to achieve such an anatomic evaluation of the urethrovesical junction (UVJ).

The last decade has seen an increase in patients suffering from complications related to midurethral slings and prolapse procedures that include transvaginal placement of mesh. Endoscopic evaluation of the lower urinary tract is an essential component of the evaluation of lower urinary tract symptoms associated with prior surgical implantation of mesh and is listed in recent diagnostic algorithms. Endoscopy also has a major role in treating some of these mesh complications ( ).

Operative cystourethroscopy in the female lower urinary tract includes minor procedures that can be performed in an ambulatory setting through an operative cystoscope, as well as the use of a cystoscope to facilitate other operations. In the former category, cystourethroscopy is commonly used to perform urethral bulking injections and intravesical botulinum toxin type A injections. In the latter category, intraoperative cystoscopy is an important adjuvant to midurethral sling procedures and facilitates the surgical repair of urinary tract fistula and urethral diverticula. It is also invaluable to evaluate the ureters and bladder mucosa for inadvertent damage at the time of surgery and to ensure the safe placement of ureteral catheters and suprapubic catheters.

Instrumentation

Rigid cystoscope

There are three components to the rigid cystoscope: the telescope, the bridge, and the sheath ( Fig. 12.1 ). Each is available with various options to facilitate its role under different circumstances. The telescope transmits light to the bladder cavity and an image to the viewer. Telescopes designed for cystoscopy are available with several viewing angles, including 0 degrees (straight), 30 degrees (forward-oblique), 70 degrees (lateral), and 120 degrees (retroview), to facilitate inspection of the entire bladder wall ( and ). Although the 0-degree lens is ideal for urethroscopy, it is insufficient for cystoscopy. The 30-degree lens provides the best view of the bladder base and posterior wall, and the 70-degree lens permits inspection of the anterior and lateral walls. The retroview of the 120-degree lens is not usually necessary for cystoscopy of the female bladder but can be useful for evaluating the urethral opening into the bladder. Angled telescopes have a field marker to help facilitate orientation, visible as a blackened notch at the outside of the visual field opposite the angle of deflection.

The cystoscope sheath provides a vehicle for introducing the telescope and distending medium into the vesical cavity. Sheaths are available in various calibers, ranging from 17 to 28 French for adults and smaller calibers for pediatric patients. Cystoscopic sets include obturators that fit the sheath and smooth the end to minimize trauma during introduction to the urethra. When the telescope, which measures 15 French, is placed within the sheath, it only partially fills the lumen, leaving an irrigation-working channel. The smaller sheath is better tolerated for diagnostic procedures, whereas the larger-caliber sheaths provide space to accommodate instruments in the irrigation-working channel. The proximal end of the sheath has two irrigating ports: one for introduction of the distending medium and another for removal of the medium. The distal end of the cystoscope sheath is fenestrated to permit use of instrumentation in the angled field of view. It is also beveled, opposite the fenestrae. Many urogynecologists forego the sheath obturator in introducing the cystoscope to the relatively short and straight female urethra, instead using the bevel to depress the posterior urethral wall, increasing the comfort of introduction of the cystoscope. Bevels increase with the diameter of the cystoscope, and larger sheaths may require an obturator for atraumatic placement.

The bridge serves as a connector between the telescope and sheath and forms a watertight seal with both. It may also have one or two ports for the introduction of instruments into the irrigation-working channel. The Albarran bridge is a variation that has a deflector mechanism at the end of an inner sheath (see Fig. 12.1 ). When placed in the cystoscope sheath, the deflector mechanism is located at the distal end of the inner sheath within the fenestra of the outer sheath. In this location, elevation of the deflector mechanism assists the manipulation of instruments and ureteral catheters within the field of view.

Rigid urethroscope

The rigid urethroscope is a modification of the cystoscope designed exclusively for evaluation of the urethra ( Fig. 12.2 ). Because it is primarily a diagnostic instrument, it does not have a bridge. The telescope is shorter and has a 0-degree viewing angle, which provides an optimal circumferential view of the urethral lumen, because the mucosa in front of the urethroscope is distended by the distention medium.

The urethroscope sheath is designed to maximize distention of the urethral lumen. The proximal end of the sheath has a single irrigating port, and the telescope only partially fills the sheath, leaving space for the irrigant to flow around it. Sheaths are available in 15- and 24-French calibers. If tolerated, the larger sheath is useful, because it provides the best view of the urethral lumen by providing more rapid fluid flow for maximal distention.

Flexible cystoscope

Unlike the rigid cystoscope, the flexible cystoscope combines the optical systems and irrigation-working channel in a single unit. The coated tip is 15 to 18 French in diameter and 6 to 7 cm in length; the working unit makes up half the length. The optical system consists of a single image-bearing fiberoptic bundle and two light-bearing fiberoptic bundles. The fibers of these bundles are coated, parallel coherent optical fibers that transmit light even when bent. The fiber coating results in a somewhat granular image, and the delicate 5- to 10-μm diameter makes them susceptible to damage. Gentle handling is essential to good visualization and instrument longevity. The flexibility of the fibers permits a distal tip-deflecting mechanism, controlled by a lever at the eyepiece that will deflect the tip 290 degrees in a single plane. The optical fibers are fitted to a lens system that magnifies and focuses the image. The irrigation-working port enters the instrument at the eyepiece opposite the deflecting mechanism (see ).

Many urologists prefer the flexible cystoscope because of improved patient comfort. However, the short length of the female urethra means that rigid cystoscopy is well tolerated by most women. Moreover, there are several disadvantages to the flexible cystoscope. The flow rate of the irrigation-working channel is approximately one-fourth that of a similar-size rigid cystoscope and is further curtailed by the passage of instruments down this channel. Some tip deflection is also lost with use of the instrument channel. In addition, because the view afforded by the flexible cystoscope is not as clear as that of a rigid cystoscope, greater operator skill is required to completely visualize the vesical cavity. There is no difference in the postprocedural morbidity compared with rigid cystourethroscopy.

Light sources and video monitors

Although any light source that provides adequate illumination via a fiberoptic cable is sufficient, a high-intensity (xenon) light source is recommended for the use of video monitoring or photography. The cable attaches to the telescope at the eyepiece. Light cables are usually fiberoptic, although fluid-filled cables are also available; they tend to be more expensive and more durable. Fiberoptic cables use flexible optic fibers that are comparable to those of the flexible cystoscope and are similarly prone to damage.

Although all cystoscopic procedures can be performed with direct visualization through the eyepiece, video monitoring eliminates awkward positioning required for direct visualization. It permits video documentation, which facilitates teaching. The video camera attaches directly to the eyepiece and should be maintained in an upright orientation. Changing the direction of view is accomplished by rotating the cystoscope without moving the camera.

Distending media

The three types of distention media are nonconductive fluids, conductive fluids, and gases. Cystourethroscopy is feasible with carbon dioxide, but most practitioners prefer to use water or saline to distend the bladder and urethra. A liquid medium prevents the carbon dioxide from bubbling and washes away blood or debris that can limit visualization. Moreover, the bladder volumes achieved using liquid medium more accurately approximate physiologic volumes.

The choice of liquid medium depends on the planned procedure. For diagnostic cystourethroscopy, sterile water is an ideal medium that is readily available and inexpensive. If absorption of a large volume of fluid into the vascular space is anticipated, an osmotic solution such as normal saline should be used. Similarly, if electrocautery is to be used, a nonconducting solution, such as glycine, should be used. A liquid medium is instilled via gravity through a standard intravenous infusion set. The bag should be at a height of approximately 100 cm above the patient’s pubic symphysis to provide adequate flow.

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