Ureteroscopy in Particular Situations






Generalities


Ureteroscopy in children, in pregnancy, and in patients with reno-ureteral malformations present certain particular aspects regarding the diagnostic algorithm, operative technique, and postoperative follow-up.


The difficulties regarding retrograde endoscopic treatment in these cases derive from the particular anatomic aspects, as well as the characteristics that limit the use of some types of common instruments during ureteroscopy in the “index patient,” as defined by the EAU/AUA Consensus ( ).


Thus, classic rigid and semirigid endoscopes are inadequate for ureteroscopy in children, pregnancy, or patients with malformations, due to their design and dimensions adapted to the upper urinary tract of the standard adult. At the same time, the physiological characteristics of pregnant women limit the use of fluoroscopy during the procedure.


Due to these technical problems, a significant number of patients were ineligible for minimally invasive treatment. Solving this problem required the search for viable solutions.


The development of miniaturized semirigid and flexible ureteroscopes, as well as of modern energy sources, has allowed the broadening of the indications of retrograde endoscopy to now include these categories of patients.


Although the retrograde ureteroscopy technique in these situations is similar to the standard one, there are some particularities that must be known and applied in order to achieve optimal results with minimal morbidity.





Ureteroscopy in children


Although the first retrograde ureteroscopic evaluation was performed by Hugh Hampton Young in 1929 on a 2-month-old child with bilateral hydronephrosis secondary to posterior urethral valves ( ), the introduction of the retrograde approach of the upper urinary tract in pediatric patients was the result of a long evolution of endoscopic instruments and technique. Only in 1998 did the results published by Ritchey and Shepard mark a new era in the use of ureteroscopy in children ( ).


Currently, retrograde ureteroscopy is considered a safe technique for the diagnosis and treatment of upper urinary tract conditions in children. The main indications are represented by :




  • the diagnosis of high origin hematuria or filling defects



  • upper urinary tract lithiasis



  • upper urinary tract obstruction (ureteral or ureteropelvic junction stenosis, caliceal diverticula, etc.)




Diagnostic Ureteroscopy


Diagnostic ureteroscopy is a technique performed more and more frequently in pediatric patients. The most frequent indication for diagnostic ureteroscopy is represented by essential benign hematuria, its incidence being of 1.3/1000 children ( ). In contrast to adults, most lesions detected in children are benign (glomerular, interstitial, vascular, or urothelial). The treatment of these lesions is more often pharmacological and conservative, rather than surgical ( ). The ureteroscopic examination technique in these situations is similar to adult diagnostic ureteroscopy.



Upper Urinary Tract Lithiasis



Indications


Currently, the minimally invasive therapeutic methods have replaced open surgery in the treatment of upper urinary tract lithiasis in children. However, the debate continues regarding the efficacy and safety of the different options.


The progress and miniaturization of semirigid and flexible ureteroscopes that allow for the use of a large variety of accessory instruments has made possible their use in children.


The therapeutic attitude for ureteral lithiasis in pediatric patients requires an individualized approach, according to the particularities of each case. It was classically considered that the possibility of spontaneous elimination of the stone is greater in children than in adults. However, recent studies suggest that in pediatric patients, for stones measuring more than 3 mm, there is a relatively low chance of passing the uretero-vesical junction.


In contrast to adults, in whom the data from the literature has demonstrated that the rate of spontaneous elimination depends on the location and dimensions of the stones, there is scarce information regarding the correlations between these parameters and the spontaneous passage of the stone in children.


Absolute indications for interventional treatment are similar to those for adults, including infection, symptoms refractory to treatment, and secondary renal function impairment. The presence of associated congenital malformations must be considered in the evaluation of these patients. In children, both SWL and retrograde ureteroscopy require general anesthesia, so from this point of view there is no difference in favor of one of the procedures.


The localization of the ureteral stone does not decisively influence the choice of treatment. Ureteroscopic approach can be considered the first therapeutic alternative for distal ureteral lithiasis in children. Proximal ureteral stones can also benefit, in good conditions, from endoscopic treatment ( ).


In case of kidney stones, extracorporeal lithotripsy is the least invasive therapeutic alternative, with a stone-free rate of over 80% and minimal complications ( ). The method’s limitations derive from the relatively high rate of repeated procedures and the need for auxiliary maneuvers.


The desire to completely extract the stones after a single procedure is an argument in favor of the ureteroscopic approach in the detriment of SWL.


The therapeutic decision also depends on the particular anatomic aspects that may be encountered in children. With the invention of flexible ureteroscopes with the possibility of obtaining an efficient deflection, even in the presence of accessory instruments inserted into the working channel, the indications for retrograde approach have broadened, including even pyelocaliceal stones.


The EAU/AUA Consensus considers SWL and retrograde ureteroscopy to be first-line methods for the treatment of upper urinary tract lithiasis in pediatric patients, the choice of one alternative or the other depending on the size and anatomic particularities of the child ( ).



Particularities of the Instruments


Modern equipment allows for the safe ureteroscopic approach in children over 3 months old ( ).


The use of adequate instruments is essential for the success of the procedures. The differences between the instruments used in children and the classic ones are minimal and generally consist of their reduced length and size.


Thus, the distal end of the semirigid ureteroscopes used in pediatric patients has a diameter of 4.7 F, which increases progressively toward the proximal end. The semirigid instruments are ideal for the approach of the ureter up to the iliac vessels, with the advantages of having two channels (one for irrigation and a working channel), superior durability, and easier maintenance.


Interventions on the proximal ureter or pyelocaliceal system can be performed under optimal conditions using flexible ureteroscopes, due to the possibilities conferred by the primary and secondary deflections. The secondary, passive deflection is rarely necessary during flexible ureteroscopy in children, the complete inspection of the pyelocaliceal system, including the lower caliceal group, being possible using a single deflection. Regarding the methods for intracorporeal lithotripsy, electrohydraulic fragmentation has proved to be effective, but is encumbered by the risk of ureteral wall lesions. The use of the Ho:YAG laser is a viable alternative, presenting the advantage of reduced aggressiveness and of obtaining fragments small enough to be eliminated spontaneously, without requiring additional active extraction maneuvers ( ).



Technical Particularities


Performing the ureteroscopic approach under optimal conditions in children requires an adequate preoperative assessment. This should include knowledge of any previous urological conditions or interventions, with direct implications on the choice of surgical technique.


Regarding the irrigation fluid, the use of water should be avoided because of the risk of circulatory absorption during the procedure, which may lead to severe intravascular hemolysis and hyponatremia. Therefore, it is preferred to use saline solution, heated to 37°C in order to prevent hypothermia that may occur during prolonged interventions. Electrosurgical procedures require the use of sorbitol, glycine, or sterile water.


Preoperative antibiotic prophylaxy is recommended in all cases.


The ureteroscopic approach in children is performed under general anesthesia. It should also be taken into consideration that urethral stimulation due to instrumentation can precipitate laryngospasm ( ).


Children under 1 year old can be positioned for flexible ureteroscopy in the supine position with legs spread, without the need of flexing them on mounts. Older patients may be positioned in the classic lithotomy position, avoiding excessive abduction of the limbs and compression on the nerve trunks. Positioning can be difficult in children with conditions such as paraplegia or spastic tetraplegia, spina bifida, etc., which can cause muscle contractures, osteopenia, or ankylosis. In these cases, an alternative that should be considered is the antegrade approach ( ).


In boys it is mandatory to examine and dilate, when necessary, the urethral meatus. Cystoscopy is performed in the same manner as for adults, and before beginning the actual procedure it is recommended to drain the bladder in order to prevent the effects of hyperpressure.


The ureteral orifice is then catheterized with a 0.035 in. guidewire. If the diameter of the intramural ureter is large enough, the ureteroscope can be ascended on the guidewire under direct visual control. The persistence of congenital ureteral folds in children may represent an element of difficulty, without being a contraindication for the ureteroscopic approach. The particularities with regard to the diameter and dimensions of the ureter in pediatric patients compared to adults, described by , require an adaptation of the surgical technique. In children, the average diameter of the ureter ranges between 2 mm and 5 mm. The morphological particularities depend on the patient’s age and size. Four areas of physiological narrowing of the ureteral lumen have been described in children: the ureteral orifice, the intramural ureter, the crossing with the iliac vessels, and the ureteropelvic junction.


Ureteroscopic access to the upper urinary tract can be facilitated by using two guidewires: one for safety and one ascended through the endoscope’s working channel. In case of difficulties passing the ureteral orifice, the flexible ureteroscope can be rotated, helping to overcome the narrowed area of the lumen. If these maneuvers are ineffective, dilatation of the ureteral orifice is recommended.


The use of the balloon catheter ( Fig. 13.1 ) is an effective and safe maneuver, but dilation is usually greater than that required for ureteroscopic approach ( Fig. 13.2 ) ( ).




Figure 13.1


Balloon dilation of the ureteral orifice.



Figure 13.2


Aspect of the ureteral orifice after dilation.


When dilation is required, this may also be carried out using a sheath with a progressive external diameter from 6 F to 10 F. This type of active dilation is best performed on a more rigid guidewire.


Active dilation is necessary in approximately 30% of the cases in which ureteroscopy is performed in children, and age is not a predictive factor regarding the indication for this maneuver ( ).


If the active dilation methods are ineffective, passive dilation with a JJ catheter is recommended.


This alternative can be used in prepubertal children in order to reduce the risk of injuring the intramural ureter and of vesicoureteral reflux. It is recommended to use 3.7–4.8 F ureteral autostatic catheters, which are maintained for 3–14 days. Prophylactic antibiotic treatment is recommended as long as the catheter is maintained.


When therapeutic maneuvers are to be performed, it is recommended to maintain a safety guidewire. The use of hydrophilic safety guidewires is contraindicated because of the risk of accidental or spontaneous extraction.


The approach of the upper urinary tract can also be achieved using a ureteral access sheath with a diameter between 10 F and 14 F, this usually requiring pre-procedural stenting.


For calculi located in the distal and middle ureter, the ureteroscopic approach can be achieved using semirigid mini-ureteroscopes ( Fig. 13.3 ). Stones located in the proximal ureter may be approached in the same manner, but sometimes it is necessary to use flexible ureteroscopes. Pyelocaliceal stones require flexible ureteroscopic approach.




Figure 13.3


Retrograde ureteroscopic approach for ureteral lithiasis in a child using a semirigid mini-ureteroscope.


Small stones can be extracted with various accessory instruments (forceps, basket catheters, etc.), while large stones require lithotripsy, in situ or after mobilization into the suprajacent ureteral segment. Currently, the Ho:YAG laser is considered by most authors the preferred method of lithotripsy.


The indications for postoperative ureteral stenting are similar to ureteroscopy in adults, being represented especially by the cases that require laborious interventions with ureteral orifice dilation, with lesions or edema of the ureteral wall, or after incisions of the urinary tract.


Due to the fact that maintaining an eventual wire attached to the distal end of the stent cannot be taken into consideration in pediatric patients (because of the risk of accidental extraction), the removal of the autostatic catheter requires a second general anesthesia ( ).


Retrograde ureteroscopic procedures in children who have a history of bladder neck reconstruction requires the use of small diameter endoscopes to avoid iatrogenic lesions of this area.


In patients with ureterocystoneostomy, the approach of the terminal ureter depends on the type of reimplantation. Additional difficulties may arise in cases with crossed reimplantations, in which access to the terminal ureter is hindered by the position and intramural tract. In these situations, catheterization of the neo-orifice with a guidewire with an angled end or with a distal end with active deflection is recommended. After gaining access, the guidewire can be replaced, on the catheter, with a rigid guidewire that facilitates ureteroscopic access. In the case of a very difficult access, the use of an antegrade approach will also be assessed.



Results


According to various studies, the stone-free rate after ureteroscopic treatment was approximately 89%, depending especially on the location of the stones ( ).


Schuster reported a 7-year experience in the treatment of ureteral calculi in children, studying a group of 25 cases. The stone-free rate was 92% after one procedure and 100% after two procedures. No intraoperative complications were described ( ).


There are still debates regarding the risk of vesicoureteral reflux after aggressive dilation of the upper urinary tract’s distal segment ( ). Studies in which post-ureteroscopic mictional cystographies were performed demonstrated that dilation of the ureteral orifice to over 12 F did not determine a significant reflux ( ).



Upper Urinary Tract Stenosis


Open surgical pyeloplasty was long considered the treatment of choice in adult ureteropelvic junction stenosis, with a success rate of over 95%. Lately, technical evolution has brought into the spotlight the endoscopic and laparoscopic methods of treatment, with a low associated morbidity and comparable success rates. Expanding the indications to include children was a natural consequence, but the results obtained up to now are not sufficient to determine with certainty the place of these methods in the therapeutic armamentarium of pediatric urology.


Starting from this premise, choosing the therapeutic option for ureteropelvic junction stenosis in children must take into consideration numerous aspects: the success rates of endopyelotomy compared to the other methods, the risks involved including bleeding, the need for open surgery in case of procedure failure, or the possibility of progressive renal function impairment.


From a technical point of view, endopyelotomy in children is carried out in a manner similar to interventions in adults.


The incision should be performed in a posterolateral position until the peripyelic and periureteral fat are visualized. Cold-blade knife, electrocautery, or laser can be used. Ureteral endoprosthesis with a 6–8 F/12–14 F pyelostent for 4–6 weeks is recommended at the end of the intervention.


As in the case of endopyelotomy performed in adults, the success rate depends on a number of factors. Thus, a reduction of the relative kidney function below 25%, severe hydronephrosis, or the presence of polar vessels are negative prognostic factors, representing contraindications of retrograde endopyelotomy ( ).


Gerber and Bogaert reported favorable results of the method in children over 4 years old with primary or secondary ureteropelvic junction stenosis without polar vessels. However, due to the small number of patients (three and eight cases respectively), the published data must be validated by other studies ( ).


Evaluating the results of retrograde endopyelotomy after the failure of pyeloplasty, Braga reported a modest success rate of only 39% ( ).


Ureteral stenosis is relatively rare in children, in most cases their occurrence being secondary to endoscopic manipulation of the upper urinary tract. Retrograde endoureterotomy is recommended especially for distal ureteral stenosis, while stenosis of the proximal or middle ureter benefits from antegrade endoureterotomy as the first therapeutic alternative.


Retrograde endoureterotomy technique follows the same principles as in adults, the placement of a stent with the highest caliber tolerated by the patient (usually 4.5–7 F) being recommended ( ).





Diagnostic Ureteroscopy


Diagnostic ureteroscopy is a technique performed more and more frequently in pediatric patients. The most frequent indication for diagnostic ureteroscopy is represented by essential benign hematuria, its incidence being of 1.3/1000 children ( ). In contrast to adults, most lesions detected in children are benign (glomerular, interstitial, vascular, or urothelial). The treatment of these lesions is more often pharmacological and conservative, rather than surgical ( ). The ureteroscopic examination technique in these situations is similar to adult diagnostic ureteroscopy.





Upper Urinary Tract Lithiasis



Indications


Currently, the minimally invasive therapeutic methods have replaced open surgery in the treatment of upper urinary tract lithiasis in children. However, the debate continues regarding the efficacy and safety of the different options.


The progress and miniaturization of semirigid and flexible ureteroscopes that allow for the use of a large variety of accessory instruments has made possible their use in children.


The therapeutic attitude for ureteral lithiasis in pediatric patients requires an individualized approach, according to the particularities of each case. It was classically considered that the possibility of spontaneous elimination of the stone is greater in children than in adults. However, recent studies suggest that in pediatric patients, for stones measuring more than 3 mm, there is a relatively low chance of passing the uretero-vesical junction.


In contrast to adults, in whom the data from the literature has demonstrated that the rate of spontaneous elimination depends on the location and dimensions of the stones, there is scarce information regarding the correlations between these parameters and the spontaneous passage of the stone in children.


Absolute indications for interventional treatment are similar to those for adults, including infection, symptoms refractory to treatment, and secondary renal function impairment. The presence of associated congenital malformations must be considered in the evaluation of these patients. In children, both SWL and retrograde ureteroscopy require general anesthesia, so from this point of view there is no difference in favor of one of the procedures.


The localization of the ureteral stone does not decisively influence the choice of treatment. Ureteroscopic approach can be considered the first therapeutic alternative for distal ureteral lithiasis in children. Proximal ureteral stones can also benefit, in good conditions, from endoscopic treatment ( ).


In case of kidney stones, extracorporeal lithotripsy is the least invasive therapeutic alternative, with a stone-free rate of over 80% and minimal complications ( ). The method’s limitations derive from the relatively high rate of repeated procedures and the need for auxiliary maneuvers.


The desire to completely extract the stones after a single procedure is an argument in favor of the ureteroscopic approach in the detriment of SWL.


The therapeutic decision also depends on the particular anatomic aspects that may be encountered in children. With the invention of flexible ureteroscopes with the possibility of obtaining an efficient deflection, even in the presence of accessory instruments inserted into the working channel, the indications for retrograde approach have broadened, including even pyelocaliceal stones.


The EAU/AUA Consensus considers SWL and retrograde ureteroscopy to be first-line methods for the treatment of upper urinary tract lithiasis in pediatric patients, the choice of one alternative or the other depending on the size and anatomic particularities of the child ( ).



Particularities of the Instruments


Modern equipment allows for the safe ureteroscopic approach in children over 3 months old ( ).


The use of adequate instruments is essential for the success of the procedures. The differences between the instruments used in children and the classic ones are minimal and generally consist of their reduced length and size.


Thus, the distal end of the semirigid ureteroscopes used in pediatric patients has a diameter of 4.7 F, which increases progressively toward the proximal end. The semirigid instruments are ideal for the approach of the ureter up to the iliac vessels, with the advantages of having two channels (one for irrigation and a working channel), superior durability, and easier maintenance.


Interventions on the proximal ureter or pyelocaliceal system can be performed under optimal conditions using flexible ureteroscopes, due to the possibilities conferred by the primary and secondary deflections. The secondary, passive deflection is rarely necessary during flexible ureteroscopy in children, the complete inspection of the pyelocaliceal system, including the lower caliceal group, being possible using a single deflection. Regarding the methods for intracorporeal lithotripsy, electrohydraulic fragmentation has proved to be effective, but is encumbered by the risk of ureteral wall lesions. The use of the Ho:YAG laser is a viable alternative, presenting the advantage of reduced aggressiveness and of obtaining fragments small enough to be eliminated spontaneously, without requiring additional active extraction maneuvers ( ).



Technical Particularities


Performing the ureteroscopic approach under optimal conditions in children requires an adequate preoperative assessment. This should include knowledge of any previous urological conditions or interventions, with direct implications on the choice of surgical technique.


Regarding the irrigation fluid, the use of water should be avoided because of the risk of circulatory absorption during the procedure, which may lead to severe intravascular hemolysis and hyponatremia. Therefore, it is preferred to use saline solution, heated to 37°C in order to prevent hypothermia that may occur during prolonged interventions. Electrosurgical procedures require the use of sorbitol, glycine, or sterile water.


Preoperative antibiotic prophylaxy is recommended in all cases.


The ureteroscopic approach in children is performed under general anesthesia. It should also be taken into consideration that urethral stimulation due to instrumentation can precipitate laryngospasm ( ).


Children under 1 year old can be positioned for flexible ureteroscopy in the supine position with legs spread, without the need of flexing them on mounts. Older patients may be positioned in the classic lithotomy position, avoiding excessive abduction of the limbs and compression on the nerve trunks. Positioning can be difficult in children with conditions such as paraplegia or spastic tetraplegia, spina bifida, etc., which can cause muscle contractures, osteopenia, or ankylosis. In these cases, an alternative that should be considered is the antegrade approach ( ).


In boys it is mandatory to examine and dilate, when necessary, the urethral meatus. Cystoscopy is performed in the same manner as for adults, and before beginning the actual procedure it is recommended to drain the bladder in order to prevent the effects of hyperpressure.


The ureteral orifice is then catheterized with a 0.035 in. guidewire. If the diameter of the intramural ureter is large enough, the ureteroscope can be ascended on the guidewire under direct visual control. The persistence of congenital ureteral folds in children may represent an element of difficulty, without being a contraindication for the ureteroscopic approach. The particularities with regard to the diameter and dimensions of the ureter in pediatric patients compared to adults, described by , require an adaptation of the surgical technique. In children, the average diameter of the ureter ranges between 2 mm and 5 mm. The morphological particularities depend on the patient’s age and size. Four areas of physiological narrowing of the ureteral lumen have been described in children: the ureteral orifice, the intramural ureter, the crossing with the iliac vessels, and the ureteropelvic junction.


Ureteroscopic access to the upper urinary tract can be facilitated by using two guidewires: one for safety and one ascended through the endoscope’s working channel. In case of difficulties passing the ureteral orifice, the flexible ureteroscope can be rotated, helping to overcome the narrowed area of the lumen. If these maneuvers are ineffective, dilatation of the ureteral orifice is recommended.


The use of the balloon catheter ( Fig. 13.1 ) is an effective and safe maneuver, but dilation is usually greater than that required for ureteroscopic approach ( Fig. 13.2 ) ( ).


Oct 10, 2019 | Posted by in UROLOGY | Comments Off on Ureteroscopy in Particular Situations
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