Ureteroscopy refers to the direct visualization of the ureter and renal pelvis using an endoscope. It is indicated for the treatment of numerous conditions, including renal and ureteral stones, ureteropelvic junction obstructions, ureteral strictures, and upper tract malignancies. It may also be performed to remove foreign bodies, such as a proximally migrated ureteral stent. Finally, it may be performed to evaluate abnormal urine cytology ﬁndings, ﬁlling defects on retrograde pyelography, or hematuria.
Ureteroscopes are small endoscopes that can be either semirigid (minimal bending of the straight metal shaft) or ﬂexible (with an actively or passively deﬂectable distal tip). Both types feature optics consisting of either ﬁberoptic bundles or, more recently, a distal sensor. All ureteroscopes have at least one working channel, which is used for irrigation and through which laser ﬁbers, stone baskets, and other devices may also be deployed. The size (outer diameter) of a ureteroscope is given in the French scale (1 Fr 0.33 mm).
URETEROSCOPY: DEVICE DESIGN AND DEPLOYMENT
Semirigid ureteroscopes are primarily used to diagnose or treat pathology in the mid to distal ureter (i.e., below the iliac vessels). They have a tapered distal tip and typically possess one large working channel or two smaller working channels. The advantages of semirigid ureteroscopes over ﬂexible ureteroscopes include larger working channels, improved stability in the distal ureter, and easier ureteral access. Disadvantages include the potential for urethral trauma during ureteroscope insertion, as well the potential for ureteral trauma during intubation of the ureteric oriﬁce and manipulation of the ureteroscope within the ureter.
Flexible ureteroscopes can be used to access any area of the upper urinary tract, but they are primarily used to access the proximal ureter (i.e., above the iliac vessels) and renal pelvis. Contemporary ﬂexible ureteroscopes provide dual deﬂecting capability of approximately 120 to 170 degrees in one direction and 170 to 270 degrees in the other direction, controlled using a thumb- operated lever. At present, all ﬂexible ureteroscopes have a single working channel. The ﬂexibility of the ureteroscope decreases when an instrument is present in the working channel; however, small-diameter holmium laser ﬁbers have been developed that are both ﬂexible and durable, causing only minimal resistance during deﬂection.
Before undergoing ureteroscopy, the patient should have a documented negative urinalysis and urine culture, so as to reduce the risk of urosepsis.
The majority of ureteroscopic procedures are performed in a specialized cystoscopy suite. The patient is placed in a dorsal lithotomy position, with the lower extremities in stirrups. Either general or regional anesthesia is employed.
The procedure is typically initiated by visualizing the bladder lumen with a cystoscope (see Plate 10-37) and then deploying a guide wire into the ureteric oriﬁce. The guidewire may be placed with either a rigid or ﬂexible cystoscope, depending on surgeon preference. Next, a ureteral catheter is inserted over the wire, and a retrograde pyeloureterogram is performed to evaluate the anatomy of the upper tract and provide a map for deployment of the ureteroscope.
After the ureteral catheter has been withdrawn, the ureteroscope can be deployed. A semirigid uretero- scope is inserted adjacent to the wire. The wire, which provides a map of the upper urinary tract, can remain in place throughout the procedure. A ﬂexible ureteroscope, in contrast, is deployed over the wire. Once it is in position, the wire must be withdrawn from the working channel to permit normal deﬂection and the introduction of devices. Thus before deployment of a ﬂexible ureteroscope, a second guide wire is typically inserted to act as a “safety” wire, which remains present throughout the entire procedure and provides access to the upper urinary tract should normal anatomy become disrupted. To place a safety wire, a coaxial dilator/ sheath is introduced over the ﬁrst wire. The inner dilator is removed, the safety wire is introduced through the sheath, and then the sheath is removed.
When a ﬂexible ureteroscope is being used, a ureteral access sheath can be placed early on to facilitate multiple insertions of the ureteroscope and limit the trauma associated with each passage. These sheaths also facilitate drainage of irrigation ﬂuid, therefore permitting more frequent ﬂushing of stone fragments and other debris created during lithotripsy procedures. Many different sheaths are available with a wide range of diameters and lengths. A ureteral access sheath is introduced over a wire. A tapered inner obturator in its lumen facilitates its passage through the ureter and helps dilate narrowed regions that would otherwise be difﬁcult to traverse. Once the sheath is in position, the inner obturator and guide wire are removed. The ureteroscope can then be deployed through the sheath lumen. At the end of the procedure, the sheath is removed under direct vision.
As the ureteroscope is advanced to the desired position, ﬂuoroscopy is performed to monitor its progress in real time. Throughout the process, the urinary tract is irrigated with saline to facilitate ureteroscope passage and improve visualization. Irrigation pressure can be controlled by gravity, a compression bag, or hand-held pumps. If passage of the ureteroscope is difﬁcult, the ureter may be dilated by passing a balloon dilator over the guide wire. Once the ureteroscope has reached the level of interest, various instruments can be introduced into the working channel to perform a diagnostic (e.g., biopsy) or therapeutic (e.g., ablation, stone basketing) procedure.
At the end of the procedure, a ureteral stent should be deployed if a ureteral access sheath has been used because the latter is associated with a risk of mucosal injury and postoperative ureteral edema. Ureteral stents are typically biocompatible polyethylene or silicone polymer devices. Most stents have curls at their proximal and distal ends, which help anchor them in the renal pelvis and bladder. In addition, most stents have small holes along their shaft to facilitate drainage. A ureteral stent may be placed through the working channel of a rigid cystoscope, or it can be deployed over a wire using ﬂuoroscopic guidance. A plastic tube known as a stent pusher is used to ensure that the proximal curl reaches the renal pelvis. Care must be taken not to advance the distal curl into the ureter.
STONE FRAGMENTATION AND EXTRACTION
When performed properly, ureteroscopy is associated with few complications. The most common complications include stent colic (discomfort from the ureteral stent), transient hematuria, and urinary tract infection. The most concerning complication is ureteral perforation. Most cases of ureteral perforation, however, successfully heal with stent deployment alone. Ureteral avulsion is a rare complication of ureteroscopy that is most often repaired using open surgical technique.
Ureteroscopy is typically performed on an outpatient basis and does not require hospital admission. At present, there is no standard protocol for postoperative follow-up. A typical evaluation to rule out residual stone disease or stricture formation may include CT scan; radiograph of the kidneys, ureter, and bladder; or renal ultrasound. If a ureteral stent is placed after an uncomplicate ureteroscopy, it is usually removed 3 to 14 days later.