Ureteroscopy 

Ureteroscopy is defined as upper urinary tract endoscopy performed most commonly with an endoscope passed through the urethra, bladder, and then directly into the upper urinary tract. Indications for ureteroscopy have broadened from diagnostic endoscopy to various minimally invasive therapies.

See image below.

Endoscopic lithotripsy, treatment of upper urinary tract urothelial malignancies, stricture incisions, and ureteropelvic junction obstruction repair are all current treatments facilitated by contemporary ureteroscopic techniques. Because the application of ureteroscopic procedures has evolved from a diagnostic tool to a facilitator in complex therapeutic interventions, a proportional increase in the rate and severity of complications would be expected. However, with improved instrumentation and evolution of surgical technique, the complication rate associated with ureteropyeloscopy has actually decreased significantly.

The progression from cystoscopy to upper urinary tract endoscopy was natural, with pediatric cystoscopes being used as the first rigid rod-lens ureteroscopes. Relatively large rod-lens endoscopes, averaging 12F (3F = 1 mm) in diameter, combined with ultrasonic and electrohydraulic lithotripsy probes became the first commonly accepted ureteroscopic equipment combination used to treat distal ureteral calculi.

Ureteroscopic treatment of calculi and, in particular, distal ureteral stones was the first common application of upper urinary tract endoscopy. Early in this evolution, smaller and more precise instrumentation was obviously found to cause less trauma to normal tissues. Rigid ureteroscopes progressed from rod-lens imaging to fiberoptic imaging with outer-diameter miniaturization. The narrow and delicate distal ureter once required vigorous balloon dilation for ureteroscopic access; however, by 1989, the fiberoptic-based rigid endoscopes were small enough (averaging 7F in diameter) for frequent placement in the distal ureter under direct vision. The small rigid ureteroscopes combined with both laser and pneumatic lithotriptors are currently used to treat distal ureteral calculi in both university and community settings.

Flexible ureteroscopy was an attractive alternative to rigid ureteroscopy in that the more proximal ureter and intrarenal collecting system was theoretically more easily accessible with this type of instrument. The application of flexible ureteroscopy was first reported by Marshall in 1964.^[1] A 9F fiberscope manufactured by American Cystoscope Makers (Pelham Manor, NY) was passed into the ureter to visualize an impacted ureteral calculus. These first flexible ureteroscopes were not capable of being directed and did not have a working channel, thus permitting only the most primitive diagnostic maneuvers. The subsequent addition of a cystoscopically placed guide tube facilitated placement of the first flexible ureteroscopes. In addition, irrigant then could be passed through the guide tube to displace the ureteral mucosa and debris from the distal endoscopic lens.

In the early 1980s, Bagley, Huffman, and Lyon began work at the University of Chicago to develop an improved flexible fiberoptic ureteropyeloscope.^[2] Three major design changes improved the potential of the flexible ureteroscope. First, the addition of a working channel allowed irrigant and endoscopic accessories to be passed directly through the endoscope rather than through an operating sheath. Second, active tip deflection allowed the endoscope to be directed or steered to areas of interest. Finally, by altering the stiffness (ie, based on durometer measurements) of the endoscope shaft, the actively deflecting portion could be combined with passive buckling of the endoscope (ie, secondary deflection), which facilitated lower-pole intrarenal access as depicted below.

The first steerable, actively deflectable, flexible ureteropyeloscopes were equipped with relatively large fiberoptic bundles for imaging and illumination. The addition of the working channel and a cable-and-pulley system used for active tip deflection required on outer diameter of 3.6 mm. By the late 1980s, optical fiber miniaturization and improved geometrical pixel packing produced a smaller fiberoptic bundle and thus, a smaller-diameter endoscope. Flexible ureteroscope specifications in 1990 included a 10F outer diameter, a standard 3.6F working channel, and unidirectional active tip deflection. Working sheaths were abandoned for direct guidewire endoscope placement, but intramural ureteral dilation was often required for placement of the flexible ureteroscope into the upper urinary tract. These endoscopes were used to inspect the entire intrarenal collecting system and became part of the standard evaluation of filling defects of the upper urinary tract defined using contrast imaging studies.

The introduction of a new generation of flexible ureteroscopes, which offer greater active deflection, has significantly advanced the therapeutic and diagnostic efficacy of the flexible ureteroscope, allowing for greater access to all aspects of the upper urinary tract.

Currently, rigid and flexible ureteroscopes average 7.5F in tip diameter and are passed atraumatically into the upper urinary tract without intramural dilation. These endoscopes are used to treat various upper urinary tract disorders, including stones, urothelial malignancies, stricture disease, and bleeding lesions. The addition of laser energy applied through optical quartz fibers passed through the working channel of the endoscope has facilitated these treatments. Specific treatments are discussed further in subsequent sections of this article.

Ureteroscopy is used as a diagnostic tool in situations such as investigating abnormal imaging findings, assessing obstruction or unilateral essential hematuria, or localizing the source of positive urinary cytology results.

Therapeutic uses of ureteroscopy have broadened to include various minimally invasive therapies. Endoscopic lithotripsy (treating stones), treatment of upper urinary tract urothelial malignancies, stricture incisions, and ureteropelvic junction obstruction repair are all current treatments facilitated by contemporary ureteroscopic techniques.

Frequency

Ureteroscopy is a routine procedure performed by urologists. The most common indication is to treat upper urinary tract calculi, particularly those that are either unsuitable for extracorporeal shockwave lithotripsy or are refractory to that form of treatment. Other common indications include evaluation of an abnormal lesion revealed by less invasive imaging tools (eg, intravenous pyelography [IVP], MRI, CT scanning) or localization of the source of positive urine culture or cytology results. Thus, ureteroscopy is often an essential part of the diagnostic algorithm and can also be used to treat the underlying disorder.

Diagnostic indications for ureteropyeloscopy are as follows:

• Abnormal imaging findings - Filling defect
• Obstruction - Determination of etiology
• Unilateral essential hematuria
• Localizing source of positive urinary cytology results, culture results, or other test results
• Evaluation of ureteral injury

Therapeutic indications for ureteropyeloscopy are as follows:

• Endoscopic lithotripsy
• Retrograde endopyelotomy
• Incision of ureteral strictures
• Improvement of calyceal drainage
• Treatment of calyceal diverticular lesions
• Treatment of malignant urothelial tumors
• Treatment of benign tumors and bleeding lesions

The ureter has 3 physiologic narrowings: (1) the ureteropelvic junction, (2) the crossing over the iliac vessels, and (3) the ureterovesical junction. This is crucial in the manifestations of calculus disease. These narrowings may result in ureteral stones becoming trapped and obstructing at these specific levels. For more information about the relevant anatomy, see Ureter Anatomy.

The segments of the ureter in which calculi can become lodged are also natural barriers for the ureteroscope. The intramural ureter is the narrowest segment and can prohibit endoscope passage. Guidewires are often passed into the ureteral orifice cystoscopically and are then directed into the renal pelvis with fluoroscopic assistance. These safety guidewires straighten the ureter and facilitate (1) the dilation of obstructed segments with balloon or graduated dilators and (2) the placement of internal stents used after many therapeutic procedures.

The intramural ureter once required balloon dilation for endoscope access. Currently, the small-diameter semirigid ureteroscopes are often narrower than 7.5F in tip diameter, while their shaft is straight or graduated. This allows for tip access, and, when advanced, the intramural segment may also be modestly dilated (ie, dilation under direct vision). Use of a dilator or sheath to facilitate passage of the ureteroscope beyond the intramural ureter is recommended when repeated access to the ureter is expected or if the intramural ureter is unusually tight or restrictive. Otherwise, the use of such sheaths is optional and generally not required.

As the fiberoptic-based rigid ureteroscope continues proximally past the ureteral orifice, it then is inhibited by the natural curvature of the ureter as it crosses the iliac vessels, psoas muscle, and the ureteropelvic junction. If the ureter is dilated, the rigid endoscope may be safely passed proximally. If not, then conversion to an actively deflectable flexible endoscope is indicated.

Flexible ureteroscopes are passed into the upper urinary tract over a guidewire with a wireless technique. Some authors have espoused the use of a 12F or 14F operating sheath to facilitate placement of this instrument. In a recent study of 1000 consecutive flexible ureteroscopic procedures using 7.5F instruments, this was not required. The flexible ureteroscope is a particularly useful instrument, especially when a rigid endoscope cannot be placed safely into the more proximal ureter or if intrarenal inspection is required. In these cases, active and passive endoscope tip deflection is essential to completely inspect the calyces.

Lower-pole intrarenal access performed with a flexible ureteroscope is often difficult and requires both active and passive flexible ureteroscope deflections. To place the tip of the endoscope into the lower pole, the instrument must first be actively deflected and then advanced to allow the shaft below to buckle as depicted below. This maneuver, termed secondary deflection, is required in 60% of traditional flexible ureteroscopies for a complete inspection. The increased active deflection offered by new-generation flexible ureteroscopes significantly decreases the need for secondary deflection and enhances the surgeon’s ability to inspect all aspects of the renal collecting system.

Diagnostic ureteroscopy has few contraindications. Untreated urinary tract infection, endoscopy without appropriate antibiotic coverage, and uncorrected bleeding diathesis are relative contraindications.

Contraindications to therapeutic ureteroscopy (eg, lithotripsy, endopyelotomy, tumor therapy) are more numerous and can mirror those associated with the corresponding more invasive open surgical intervention. In general, the major contraindications are related to untreated infections and uncorrected bleeding diathesis prior to therapeutic endoscopy.