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ENDOSCOPY OF THE LOWER URINARY TRACT
CHAPTER
6
ENDOSCOPY OF THE LOWER URINARY TRACT Ranjiv Mathews
Endoscopy of the lower urinary tract has been performed in infants and children; however, the potential for therapeutic intervention was limited by the size of available instrumentation. Recent advances in the miniaturization of instruments and video technology allow all but the smallest infants to be examined and treated endoscopically if indicated.1,2 Further extension of this technology has even permitted fetal endoscopic diagnosis and, more recently, intervention (see later discussion). Most infants and children require anesthesia for performance of endoscopy. In the male, meatotomy may be necessary for introduction of larger instruments and, if indicated, should be performed before meatal injury occurs.3 Perineal urethrostomy has been performed in the past for access to the proximal urethra; however, most cases today can be performed without this added intervention. This chapter addresses endoscopy of the lower urinary tract (cystourethroscopy and antegrade endoscopy).
TECHNIQUES AND INSTRUMENTATION A cystoscopic suite that permits fluoroscopic or ultrasonographic visualization is the ideal working environment for pediatric diagnostic and therapeutic endoscopy. In infants, an open-leg posture using padded extension boards from the table is recommended. The older child can be placed in a standard lithotomy position for lower tract endoscopy. Irrigating fluids (sterile normal saline or water) are warmed to body temperature to prevent potential hypothermia during endoscopy. Normal saline solution is used in most instances to prevent significant fluid absorption. If the patient has spina bifida, exstrophy, or other major congenital anomaly with potential for latex allergy, appropriate precautions are used as indicated. Additionally, children who have myelodysplasia with significant contractures, or spinal fusion, should have their extremities and back padded well to prevent injury and the development of pressure ulcers. Endoscopic evaluations should commence with careful examination of the external genitalia to identify labial adhesions, ectopic ureters, or other morphologic anomalies that may require management. The width of the urethral meatus should be evaluated to determine whether trauma is likely to result from the cystoscope chosen for the procedure. Patients being evaluated for genital ambiguity and those with concerns for voiding dysfunction may also have a careful rectal examina tion performed at the time of cystoscopic evaluation. Pediatric versions of cystoscopes are now available from most manufacturers. Larger scopes use the Hopkins rod-lens system (Fig. 6-1). The newer, thinner, multifunction scopes have fiberoptic systems that permit visualization while providing an adequate working channel for instrumentation. Use of a video camera system allows magnification and improved visualization while permitting recording of procedures for teaching or comparison with follow-up studies. Although the cystoscopes shown are the ones I prefer, a variety of excellent instruments with similar characteristics are available from various manufacturers. It is important to have a selection of cystoscopes available for use during procedures. Most 84
endoscopes available today can be used for multiple functions. Cystoscopy, ureteroscopy, and nephroscopy can all be accomplished with currently available multifunction pediatric endoscopes.
Cystoscopes Routine cystoscopic evaluation for diagnosis can be performed with a 5F (1.65-mm) cystoscope (Fig. 6-2). This permits excellent visualization with minimal trauma to the urethra. Most 5F cystoscopes are one-piece units with a 2.5F (0.83-mm) or 3F (0.99-mm) working port. This limits their therapeutic utility to the insertion of guidewires or removal of stents or small calculi. The 7F (2.31-mm) or larger cystoscopes provide a 5F working channel that allows many pediatric instruments to be inserted. Cystoscopes with an offset lens allow a straight path for the working channel (Fig. 6-3). Flexible cystoureteroscopes are also available for pediatric applications. Most are 7.5F (2.48 mm) in diameter and provide a 3.6F (1.19-mm) working channel for instrumentation (Fig. 6-4).
Resectoscopes Rigid resectoscopes have similar setup to their adult coun terparts. A variety of loops and cautery ends have been developed. In addition, hooked and straight blades for cold knife incision are available. Most use the Hopkins rod-lens system, but fiberoptic systems are also becoming available.
Fetal Endoscopes Improvements in microendoscopy have allowed diagnosis and, more recently, therapy in the fetus. The fetal eyes appear to have natural protection against injury from the high-intensity light used during in utero–endoscopy.4 The most frequently used application of fetal endoscopy has been laser coagulation of aberrant vessels in monochorionic twins with twin-twin transfusion syndrome.5 This technology has increasingly been applied to the antenatal management of urologic abnormalities. Fetal endoscopes used to date have a diameter of 1.3 mm. Diagnosis of urethral obstruction can be made, and the technology has been extended to management. Ablation of posterior urethral valves has been performed with either a saline flush technique or guidewire insertion.6 Antegrade valve ablation has also been described.7
Working Instruments Graspers, both flexible and rigid, are available in sizes from 3F to 5F for applications through rigid and flexible scopes. Rigid graspers work well with the offset lens scopes. 3F and 5F Bugbee electrodes are also available for fulguration. Open-ended ureteral stents with a guidewire may also be modified to permit cauterization. The tip may be bent to form a coagulating hook. Recently, a 5F cutting electrode has been developed that has a retractable, angled tip for pediatric application (Fig. 6-5).
6
ENDOSCOPY OF THE LOWER URINARY TRACT Ranjiv Mathews
Endoscopy of the lower urinary tract has been performed in infants and children; however, the potential for therapeutic intervention was limited by the size of available instrumentation. Recent advances in the miniaturization of instruments and video technology allow all but the smallest infants to be examined and treated endoscopically if indicated.1,2 Further extension of this technology has even permitted fetal endoscopic diagnosis and, more recently, intervention (see later discussion). Most infants and children require anesthesia for performance of endoscopy. In the male, meatotomy may be necessary for introduction of larger instruments and, if indicated, should be performed before meatal injury occurs.3 Perineal urethrostomy has been performed in the past for access to the proximal urethra; however, most cases today can be performed without this added intervention. This chapter addresses endoscopy of the lower urinary tract (cystourethroscopy and antegrade endoscopy).
TECHNIQUES AND INSTRUMENTATION A cystoscopic suite that permits fluoroscopic or ultrasonographic visualization is the ideal working environment for pediatric diagnostic and therapeutic endoscopy. In infants, an open-leg posture using padded extension boards from the table is recommended. The older child can be placed in a standard lithotomy position for lower tract endoscopy. Irrigating fluids (sterile normal saline or water) are warmed to body temperature to prevent potential hypothermia during endoscopy. Normal saline solution is used in most instances to prevent significant fluid absorption. If the patient has spina bifida, exstrophy, or other major congenital anomaly with potential for latex allergy, appropriate precautions are used as indicated. Additionally, children who have myelodysplasia with significant contractures, or spinal fusion, should have their extremities and back padded well to prevent injury and the development of pressure ulcers. Endoscopic evaluations should commence with careful examination of the external genitalia to identify labial adhesions, ectopic ureters, or other morphologic anomalies that may require management. The width of the urethral meatus should be evaluated to determine whether trauma is likely to result from the cystoscope chosen for the procedure. Patients being evaluated for genital ambiguity and those with concerns for voiding dysfunction may also have a careful rectal examina tion performed at the time of cystoscopic evaluation. Pediatric versions of cystoscopes are now available from most manufacturers. Larger scopes use the Hopkins rod-lens system (Fig. 6-1). The newer, thinner, multifunction scopes have fiberoptic systems that permit visualization while providing an adequate working channel for instrumentation. Use of a video camera system allows magnification and improved visualization while permitting recording of procedures for teaching or comparison with follow-up studies. Although the cystoscopes shown are the ones I prefer, a variety of excellent instruments with similar characteristics are available from various manufacturers. It is important to have a selection of cystoscopes available for use during procedures. Most 84
endoscopes available today can be used for multiple functions. Cystoscopy, ureteroscopy, and nephroscopy can all be accomplished with currently available multifunction pediatric endoscopes.
Cystoscopes Routine cystoscopic evaluation for diagnosis can be performed with a 5F (1.65-mm) cystoscope (Fig. 6-2). This permits excellent visualization with minimal trauma to the urethra. Most 5F cystoscopes are one-piece units with a 2.5F (0.83-mm) or 3F (0.99-mm) working port. This limits their therapeutic utility to the insertion of guidewires or removal of stents or small calculi. The 7F (2.31-mm) or larger cystoscopes provide a 5F working channel that allows many pediatric instruments to be inserted. Cystoscopes with an offset lens allow a straight path for the working channel (Fig. 6-3). Flexible cystoureteroscopes are also available for pediatric applications. Most are 7.5F (2.48 mm) in diameter and provide a 3.6F (1.19-mm) working channel for instrumentation (Fig. 6-4).
Resectoscopes Rigid resectoscopes have similar setup to their adult coun terparts. A variety of loops and cautery ends have been developed. In addition, hooked and straight blades for cold knife incision are available. Most use the Hopkins rod-lens system, but fiberoptic systems are also becoming available.
Fetal Endoscopes Improvements in microendoscopy have allowed diagnosis and, more recently, therapy in the fetus. The fetal eyes appear to have natural protection against injury from the high-intensity light used during in utero–endoscopy.4 The most frequently used application of fetal endoscopy has been laser coagulation of aberrant vessels in monochorionic twins with twin-twin transfusion syndrome.5 This technology has increasingly been applied to the antenatal management of urologic abnormalities. Fetal endoscopes used to date have a diameter of 1.3 mm. Diagnosis of urethral obstruction can be made, and the technology has been extended to management. Ablation of posterior urethral valves has been performed with either a saline flush technique or guidewire insertion.6 Antegrade valve ablation has also been described.7
Working Instruments Graspers, both flexible and rigid, are available in sizes from 3F to 5F for applications through rigid and flexible scopes. Rigid graspers work well with the offset lens scopes. 3F and 5F Bugbee electrodes are also available for fulguration. Open-ended ureteral stents with a guidewire may also be modified to permit cauterization. The tip may be bent to form a coagulating hook. Recently, a 5F cutting electrode has been developed that has a retractable, angled tip for pediatric application (Fig. 6-5).