|Year : 2000 | Volume
| Issue : 2 | Page : 83-87
Retrograde intrarenal surgery
AK Hemal, Rajeev Kumar
Department of Urology, All India Institute of Medical Sciences, New Delhi, India
A K Hemal
Dept. of Urology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi - 110 029
| Abstract|| |
The trend in surgical practice today is towards developing minimally invasive techniques. The development of small calibre flexible instruments permits endoscopic surgery in the urinary tract to treat a wide variety of lesions within the kidney. This article reviews the indications, instruments, technique and current status of retrograde intrarenal surgery.
Keywords: Endoscopic; Retrograde; Intrarenal Surgery
|How to cite this article:|
Hemal A K, Kumar R. Retrograde intrarenal surgery. Indian J Urol 2000;16:83-7
| Introduction|| |
Endoscopic surgery using minimally invasive techniques has been the frontier of medical innovation in the last two decades. With the stress shifting towards shorter hospital stay, lower costs, improved cosmesis and earlier return to work, expanding the scope of endourology has been the natural consequence. This has been boosted further with the less than perfect results seen in cases of urolithiasis treated with extracorporeal shockwave lithotripsy (ESWL).
Transurethral ureteroscopy  and nephroscopy using both rigid and flexible instruments have evolved from the basic cystoscopic procedures already familiar to the urologists. The main concerns are the narrower lumen of the ureter, its anatomy and the need for greater caution in dilatation and manipulation. Advances have been in the form of newer actively deflectable instruments with better optics, improved intraureteral lithotripsy probes, improved knowledge of ureteral anatomy and clear definition of the indications for retrograde intrarenal surgery (RIRS).
| Definition|| |
Surgery within the renal pelvicalyceal system and parenchyma performed using instruments introduced in the retrograde fashion through the ureter and lower urinary tract is termed retrograde intrarenal surgery.
Flexible retrograde endoscopic surgery in the kidney has become possible resulting from the development of appropriate accessories for stone retrieval and fragmentation. With RIRS, a significant segment of difficult and complex cases with upper tract pathology have become routine indications for this new minimally invasive treatment.
| Indications for RIRS|| |
- Evaluation of hematuria
- Evaluation of positive upper tract cytology
- Evaluation of radiographic filling defects or obstruction
- Surveillance after conservative treatment of upper tract tumors
- Failed ESWL (stones <1.5 cm)
- RIRS assisted ESWL (stones upto 2.5 cm)
- Radiolucent stones (stones <1.5 cm)
- Concomitant renal and ureteral stones (renal stone <1 cm)
- Calyceal diverticular stones
- Stones with nephrocalcinosis
- Stones with associated anatomic obstruction
- Stones with supravesical diversion
- Rarely, partial staghorn stones
- Treatment of PUJ obstruction
- Treatment of anastomotic structures
- Treatment of urothelial tumors
- Fulguration of bleeding vessels
- Retrograde percutaneous renal puncture
| Technique|| |
Instrumentation for RIRS
- Newly designed flexible instrument with dual deflection
- Energy sources (EHL, Holmium laser with small caliber probes)
- Flexible accessories including baskets, graspers and forceps
- Suction pump
- Video camera unit
- Fluoroscopy unit
The recent advances of flexible endoscopy in the upper urinary tract have been made possible by the development of new, actively deflecting fibre-optic instruments. These are characterized by small outer diameter (7-12 Fr.), working channels of upto 4 Fr and deflecting capabilities of upto 160 degrees (and 70 degrees in the second plane in some instruments). These features have greatly improved the handling of the instruments and have increased their usefulness for diagnostic and therapeutic procedures in the ureter and kidney.
Important anatomic considerations:
A complete knowledge of the anatomy of the upper and lower urinary tracts is imperative. A few important points that need to be highlighted are:
- The ureterovesical junction is the narrowest part of the ureter and corresponds to the entrance of the ureter through the detrusor hiatus.
- The muscle layer of the ureter wall is least well developed at the pelvi-ureteral junction and also in the intramural portion. Dilatation and instrumentation at the intramural portion is the most common site for perforation and false passages.
- The mucosal cell layers are minimal in the calyces and the pelvis and become progressively thicker in the lower ureter.
- Endoscopically, the junction between the fixed and mobile portions of the ureter is visible as a bend or lip of mucosa in the posterolateral lumen and increases during inspiration.
- The mucosa derives its blood supply entirely from the underlying tissue and dissection by instrumentation may lead to complete necrosis.
- Due to its thin walls, biopsies in the proximal ureter or pelvis are very likely to cause perforations.
All patients must have a sterile urine culture before the procedure is begun and antibiotic prophylaxis to all patients is advised.
RIRS can be performed as a one step or two step procedure. In patients undergoing elective therapeutic procedures, a two step procedure may be chosen. This involves a pre-placement of ureteral stent one to two weeks prior to surgery to enable the ureter to dilate. This can be done under topical anesthesia and a retrograde pyelogram may be simultaneously done to confirm the anatomy and pathology.
In patients undergoing diagnostic evaluation, emergency RIRS or unwilling for a two stage procedure, a one stage surgery may be done with rapid dilation of the ureter. In diagnostic cases, pre-placement may obliterate vital diagnostic clues and should be avoided. Similarly contrast injection should be delayed till after collection of sample for histology. Rapid dilation can be achieved by: a) introduction of progressively larger ureteral catheters, b) passage of metal bougies and c) use of balloon dilating catheters. Balloon dilatation using screw type inflation syringes at pressures of 2 atm/minute until wasting disappears is the current favourite technique.
Both rigid and flexible instruments are available for RIRS. Rigid instruments with sheaths as small as 9.5 Fr. are available and integral sheaths with telescopes as small as 6 Fr. The integral sheaths usually lack a working channel and are used mainly for diagnostic purposes. Most small caliber ureteroscopes provide adequate irrigation rates with another channel for instrumentation. Flexible instruments are either passively or actively deflectable. The actively deflectable ones allow purposeful movement of the ureteroscope tip. Both types have irrigation and additional instrument channel.
Procedural steps: (From Fuchs  ):
- Cystoscopy and retrograde pyelography if indicated
- Passage of a guidewire into the pelvis
- Removal of indwelling catheter if previously placed
- Passage of ureteroscope alongside the guidewire
- In difficult cases, pass the ureteroscope over an additional guidewire and remove the guidewire past the iliac vessels
- Begin irrigation and advance the instrument to the site of interest
- Post procedure placement of ureteral stent for 7-14 days
| Diagnostic RIRS|| |
Two conditions of the upper urinary tract which still pose a diagnostic problem are filling defects and essential hematuria. Filling defects are usually due to radiolucent stones, tumors and clots. Essential hematuria is a diagnosis dependent on the exclusion of all other causes of hematuria. Conventional diagnostic modalities using radiology may not be sufficient to reach a diagnosis in certain cases.
Bagley et al  reported 32 patients with cystoscopically proven unilateral essential hematuria. All patients had undergone an IVU, 20 patients had angiograms, 17 computed tomograms and 11 ultrasonograms had been performed but a diagnosis not reached.
Cytology for malignant cells in cases with transitional cell cancer is positive in only 70-80% cases and usually with high grade lesions. The results are affected by concomitant infection, hematuria and obstruction. False negative results may be as high as 20-30% (Lewis et al,  and even 66% in a series of 289 patients  ). Even a blind brush biopsy may not suffice. 68 procedures carried out by Blute et, a1  had a 16% false negative rate with similar reports from other series.
Diagnostic RIRS is usually performed as a one step procedure combining rigid and flexible cysto-ureteroscopy. Cytology specimens are drawn before dye injection and a systematic inspection of the entire urothelium is carried out. Anatomic correlation with the findings on radiological investigations is done and biopsies taken from suspicious areas. A stent is usually left in situ after the procedure. Irrigation during the ureteroscopy is usually provided by a manual pressure syringe.
Bagley  in the above series of 32 patients used RIRS as a diagnostic and therapeutic modality for essential hematuria. In 28 patients, the full collecting system could be visualized. No lesion was found in 5 patients of whom 4 subsequently did not have any hematuria. A discrete lesion was found in 16 cases with a benign hemangioma being the commonest cause in 11. All 11 of these patients had fulguration and all became asymptomatic. 9 patients had diffuse abnormality of the entire collecting system and could not be controlled endoscopically.
Abdel-Razzak  conducted 55 procedures on 45 patients with variable presentation. 23 had hematuria, 19 filling defects, 1 positive cytology for malignant cells and 12 needed surveillance for urothelial cancer. On examination and biopsy using RIRS, 15 out of 22 basket samples had unequivocal results as did 16 out 21 biopsy samples and 5 out of 6 grasper samples. None of these patients could be completely evaluated using conventional techniques. Similarly, Karvoussi et al  reported a 92% success in diagnosing cause for filling defects in 25 patients while Bagley et al  reported a 100% success in 62 patients with filling defects.
| Therapeutic RIRS|| |
Concomitant diagnosis and treatment for filling defects and hematuria have already been discussed. The other major areas of benefit using RIRS are ureteropelvic junction obstruction (PUJO) and upper tract stones.
| Pujo|| |
Endopyelotomy for PUJO is no longer an investigational modality. It is extensively used in both primary and secondary obstruction. Failure of endopyelotomy does not prevent the use of open surgery as a salvage option. The results have been equivalent for open and percutaneous techniques. The current route is the approach through a percutaneous nephrostomy. The evaluation of the role of retrograde surgery is the area of investigation.
Inglis and Tolley  reported the first two cases approached using a rigid ureteroscope using a diathermy. Both cases were successfully treated. Meretyk  compared open repair with RIRS and found 78% success with either technique. However, they noted a 21% stricture rate with RIRS. Subsequently, Chowdhary et al  operated on 12 patients using combined rigid and flexible scopes and attained 83% success rates with no strictures. Chandhoke  used the Acuicise successfully in 89% of their cases with only one stricture while Thomas  using a rigid scope in 9 patients reported 100% success rates. A special indication for the RIRS technique is in ectopically positioned kidneys where traditional percutaneous access may not be feasible  .
In a similar fashion, an increasing number of patients with stenosis of the uretero-enteric anastomosis or ureteral strictures are being treated with balloon dilatation and cutting devices. This may not fit into the classical definition of RIRS but all the same, it is an essential offshoot of the same technology.
| Difficult Percutaneous Access|| |
Another therapeutic indication for RIRS is in assisting the placement of a percutaneous catheter. Grasso et al  used this combined approach in seven patients with renal disease or body habitus that made precise percutaneous access difficult. One had a large perinephric hematoma, four were morbidly obese and others had a tightly branched staghorn calculus and calyceal diverticular calculi. Using RIRS guidance, percutaneous access was achieved in all in under thirty minutes.
| Upper Tract Tumors|| |
RIRS treatment of transitional cell carcinoma of the upper tract is appropriate for selected patients and for the palliative management of patients who are not candidates for other open procedures. Tumor ablation with a 3 Fr Nd Yag laser probe or 200 micron holmium laser fiber is possible.
| Stone Disease|| |
Extracorporeal shockwave lithotripsy (ESWL) has been available to the urologists for nearly 20 years and has revolutionized the management of urolithiasis. However limitations to its use exist and the main problems are encountered in large stones, impacted or hard stones, distal obstruction or calyceal narrowing, stones lying in a dependent location or stones that are difficult to localize using radiological methods. These limitations have led to significant failure rates in most series on lithotripsy.
Grasso et al  evaluated 121 patients referred to them for management following failure of lithotripsy. Failure to clear the stones often after adequate fragmentation was the commonest cause (54 patients). The mean diameter of the stone was 22.2 mm and steinstrasse was seen in 10 patients. 3 of these patients underwent irreversible renal loss. The average number of sittings was 2.54. In 43 patients the stones did not fragment. 13 had upper tract obstruction including infundibular stenosis and calyceal narrowing while in l l the stone could not be localized on the lithotripter.
Lingeman  evaluated the results of ESWL on 2927 patients with inferior calyceal stones. A clearance rate of only 59% was achieved and there was a direct correlation with the stone burden. They also reviewed 13 other similar studies and found the lower polar stone clearance rate to vary between 25 and 84%.
Bierkens et al  performed a multicentre evaluation of the efficacy of I and II generation lithotripters. In 2206 cases, overall stone free rate was only 45% at three months if complete clearance was the criterion and 75% if less than 5 mm residual stones were discounted.
There clearly is a need for improvement on this front.
In a review on the role of RIRS in stone disease, Fuchs  suggested the following guidelines:
For residual stones following ESWL: up to 1.5 cm diameter for a solitary stone and up to 5 particles each with a diameter up to 5 mm may be tackled by RIRS. Particles greater than 5 mm need Electrohydraulic lithotripsy or holmium lithotripsy in situ. The clearance rates are upto 93% if the size was less than 5 mm and 84% if greater than 5 mm.
Radiolucent stones should be given a trial with dissolution therapy.
Impacted ureteral stones with ipsilateral renal stones should be tackled if the renal stone is less than 1 cm in size or upto 3 fragments less than 5 mm each. All ureteral stones could be cleared with rates for renal stones similar to those for patients with failed ESWL.
In patients with associated intrarenal stenosis a bugbee electrode of 2 Fr was used for incision and 84% clearance of diverticular stones achieved.
While there are series reporting successful use of RIRS in combination with ESWL for the management of complex renal stone disease , , one of the largest is the series of Patel et a1  . 45 patients underwent RIRS assisted lithotripsy. Average treatment time was 110 minutes for single sessions while 9% cases required two. 95% were treated as outpatients and there were no complications. 91% required endoscopic fragmentation and stones were simultaneously removed in 96% cases. Overall stone free rate was 85%. All these patients had either failed ESWL, intrarenal stenosis, large stone size or coagulopathy.
Renal stones with nephrocalcinosis: RIRS allows easy differentiation of stones within the renal collecting system from the submucosal and intraparenchymal calcifications. This in turn allows accurate removal or localization of ESWL beam preventing unnecessary injury to the parenchyma.
Renal stones and supravesical diversion: Endoscopy of the upper urinary tract after supravesical diversion is difficult and, with rigid instruments, often not feasible. In such cases, RIRS can be safely performed for infection induced stones which are difficult to localize with fluoroscopy type of ESWL due to air and the soft nature of stone. Moreover, the need for complete removal to prevent recurrence and eradicate a source of infection makes this one time clearance option advisable.
RIRS assisted ESWL: Simultaneous endoscopic visualization of the collecting system and ESWL has added to the efficacy of lithotripsy in the management of stone disease. It allows examination of the intrarenal collecting system and treatment of strictures or stenosis with balloon dilatation, bugbee electrodes and/or holmium laser. Once the anatomical access and egress problem has been resolved and the stone localized, ESWL can proceed. Stone fragmentation can be performed under direct visual endoscopic control. Fragmentation of larger calculi can be assisted and accelerated by simultaneous ureteroscopic use of EHL or holmium laser and clearance of fragments with baskets.
| Conclusions|| |
Flexible diagnostic ureteroscopy of the upper urinary tracts and RIRS have become an integral part of the armamentarium of the urologists. The role of the diagnostic tool is firmly established since ureteroscopy allows complete visualization of the entire renal collecting system.
Using only the conventional modalities of diagnosis and therapy, there remains a significant subset of patients that is incompletely evaluated and treated and often ends up requiring open surgical procedures. With the current stress on minimally invasive surgery, lower hospitalization and earlier return to work, endoscopic treatment must be explored fully before committing the patient to an open surgical procedure.
Despite the availability of percutaneous nephroscopic approach, retrograde endoscopy is enticing since it avoids even the small cutaneous puncture and the hassles associated with a percutaneous nephrostomy tube that often needs to be left. There are now available ureteroscopes with advanced optics that are flexible and actively deflectable apart from providing an irrigation and working channel. Along with this are available fine instruments like graspers, baskets and forceps. Lithotripsy probes of holmium lasers promise to revolutionize endoscopic stone treatment with their small diameter and effective fragmentation. With a refinement of technique, complications like stricture, perforation and extravasation can be minimized. The ability to manage patients with co-morbidities like intrarenal stenosis is an added advantage. Finally, the possibility of a single stage clearance for stone disease epitomizes the idea behind minimally invasive surgery.
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