Ureterorenoscopy

In 1980, E. Perez-Castro presented for the first time a ureterorenoscope for the endoscopic evaluation of the ureters and the renal pelvis. This was a rigid device about 50 cm long, which already had a working channel. H. Reuter used an electrohydraulic stone disintegration technique together with ureterorenoscopy for the first time 2 years later (Hofmann 2018).

Ureterorenoscopy (URS) is a retrograde endoscopic technique used for diagnostic and therapeutic purposes in the ureters and renal pelvis (Staubach 2008).

At the beginning of URS in 1980, it was a rigid instrument with which endoscopic examinations of the ureters were possible; in the meantime, miniaturization, technical improvements, improvement of optics and the introduction of flexible devices have made the possibilities of URS much more extensive (Hegele 2015).

Nowadays, rigid, semirigid and flexible ureteral endoscopes of different sizes are available. In addition, there are auxiliary instruments such as stone grasping or biopsy forceps, dormia baskets, resection loops, etc. (Steffens 2000).

Rigid instruments:

The shaft width of rigid instruments is between 6 - 9 CH, and the working channel is 5 CH. An irrigation inflow and outflow are present. They are similar in design to a cystoscope (Manski 2019).

Rigid instruments are preferred for inspection (Albers 2006).

Semirigid instruments:

Semirigid instruments have a shaft width of 5 - 7 CH (Manski 2019).

Indications are for ureteral calculi, regardless of location, for renal pelvic calculi up to 1.5 cm in size, and for calculi of the upper caliceal group also up to 1.5 cm (Risler 2008).

Flexible instruments:

The shaft thickness is between 8 - 12 CH, and the working channel is 3 CH (Manski 2019).

With flexible instruments, all calyx groups can be exposed, the examination is usually less stressful for the cavity system and ureteral splinting can often be omitted (Risler 2008). The spatial resolution is lower with flexible instruments than with rigid instruments and the flushing possibilities are limited due to the smaller diameter of the working channel (Hegele 2015).

A lot of experience of the examiner is required in handling. The examination is costly, as the instruments are on the one hand quite prone to failure and on the other hand also maintenance-intensive.

(Risler 2008)

URS can be used both diagnostically and therapeutically. It is a gentle procedure with few complications (Steffens 2000).

1 Diagnostic clarification

Indications for diagnostic URS are:

• unclear haematuria
• suspicious cytology
• radiologically unclear findings
• V. a. tumours

(Steffens 2000)

2 Therapeutic use

Therapeutic use includes ureterorenoscopic stone treatment.

URS is now an alternative to extracorporeal shock wave lithotripsy (ESWL) and percutaneous nephrolitholapaxy (PNL) (Kuhlmann 2015).

URS can be used to remove ureteral stones of ≥ 7 mm in diameter (Herold 2021).

For stones in the distal ureter, the success rate of > 95 % is significantly higher than that of ESWL with 50 % - 80 %. However, URS represents the more invasive procedure (Steffens 2000).

Indications:

• Distal and intermediate ureteral stones (preferential procedure [Kuhlmann 2015]).
• Proximal ureteral stones (alternative procedure to ESWL [Kuhlmann 2015]).
• ureteral stones with distal stenosis of the ureter (preferential procedure [Kuhlmann 2015])
• increasingly established procedure in:
  • Renal pelvic stones
  • Calyx stones

[Kuhlmann 2015)

• Ureteralstones after unsuccessful ESWL
• stone roads after ESWL
• Persistent stones after ESWL
• Treatment of:
  • ureteral strictures
  • subpelvic stenosis recurrences
• Control examination after endoureteral therapy
• insertion of double J-probes
• Removal of dislocated ureteral catheters
• Removal of dislocated slings
• Therapy of superficial ureteral tumors

(Steffens 2000)

• in selected cases with
  • Pregnant women with emergency indication
  • Emergency indication under anticoagulation

(Kuhlmann 2015)

Contraindications:

• absolute AI:
  • Coagulation disorders
  • acute urinary tract infection
• relative KI:
  • large adenomas of the prostate
  • Urethral strictures
  • post ureteral implantation (Steffens 2000)
  • complex anatomical anomalies of the urinary tract
  • increased risk of anaesthesia (Kuhlmann 2015)

Performance:

Prerequisites for the procedure are:

• inconspicuous blood laboratory
• intact coagulation parameters
• sterile urine culture
• imaging of the (upper) urinary tract
• perioperative prophylaxis with antibiotics such as 2nd generation cephalosporins (e.g. cefuroxime) or fluoroquinolones (e.g. ciprofloxacin or levofloxacin).

(Hegele 2015)

The procedure itself is usually performed under general anesthesia (Risler 2008).

The possibility of intraoperative X-ray fluoroscopy should be available.

After positioning the patient in the lithotomy position, a diagnostic cystoscopy is first performed with a rigid cystoscope. This is followed by diagnostic retrograde ureteropyelography (Hegele 2015).

Semirigid URS

Following the above preparation, a guide wire is advanced into the renal pelvis via a ureteral catheter and the semirigid ureterorenoscope is advanced into the ureter under visual control after passing through the ureteral ostium along the guide wire.

In order not to flush any stones into the renal pelvis, the flow of irrigation water should be kept as low as possible.

After the pyeloureteral junction has been passed, not only the renal pelvis but also the antegrade accessible upper calyx group can be mirrored. Any stones can be extracted using the Dormia basket, forceps, etc. Tumor-susceptible areas can be biopsied.

(Hegele 2015)

Flexible URS

The flexible ureterorenoscope is particularly suitable for

• diagnostic and therapeutic interventions in the area of the lower and middle calyx group
• In the case of special anatomical conditions such as prostatic hyperplasia, ureters in transplant kidneys, etc.

(Hegele 2015)

The flexible ureterorenoscope is advanced into the renal pelvis under radiological control via a previously inserted 2nd wire.

(Hegele 2015)

Antegrade URS

Antegrade URS is used, for example, in difficult intravesical anatomical conditions, as well as in cases of subvesical obstruction.

For this purpose, the renal pelvis is punctured percutaneously and the puncture channel is opened by balloon dilatation. With the aid of a flexible nephroscope, inspection of the renal pelvis and antegrade endoscopy of the ureter are possible.

In addition, concretions can be extracted, tissue samples can be taken and a double J- splint (DJ- splint) can also be inserted.

(Hegele 2015)

Conclusion URS

After the URS, the insertion of a DJ splint is usually recommended for 2 - 4 weeks, and in the case of larger perforations, an indwelling catheter is also recommended for a few days to allow pressure-free urine drainage.

(Manski 2019)

Overall, the complication rate is very low at ≤ 5%.

Possible complications of URS can be:

• postoperative ureteral strictures (these have become very rare at 0.1 % - 0.4 % due to improvements in instrumentation and endoscopic technique).
• ureteral rupture (0,2 %)
• Ureteral perforation (1.6 %)
• Injury to the ureteral mucosa
• fever or sepsis 1.1 % - 3.5 %
• postinterventional urinary tract infections (as these are very common, periinterventional antibiotics are given for prophylaxis)
• significant haematuria (up to 2 %)
• renal colic (up to 2.2 %)
• vesicoureteral reflux 0.1 %

(Kuhlmann 2015)

• Postoperative urinary retention (due to blood coagulation, mural edema, ureteral injury, residual stones, etc. [Manski 2019])

The success rate in nephrolithiasis depends on the location of the stones and is:

• for distal stones > 90 % (Steffens [2000] > 95 %)
• with proximal stones 60 % - 90 %
• for renal pelvic stones 60 % - 80 %

(Kuhlmann 2015)

The passive ureteral stent should be removed after 2 - 4 weeks (Manski 2019).

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