Prediction of need for intervention in posterior urethral valves: Use of urine osmolality.

AIM: Renal tubular dysfunction (RTD) causing obligate production of hypoosmolar urine in boys with posterior urethral valves (PUVs) has been described. It is not known how clinically significant this is. We hypothesize that a feedback loop is present in many PUV boys who suffer deterioration of their lower urinary tract (LUT). RTD results in hypoosmolar urine, obligate polyuria, and bladder stretch-injury. The increasing back-pressure worsens RTD, thus exacerbating the injury. Coexisting renal dysplasia and acquired renal scarring exacerbate this. We compared the concentrating ability (random clinic urine osmolality) of PUV boys who had no LUT deterioration to those who required intervention, examining the confounding effect of renal impairment with a subgroup analysis comparing those with plasma creatinine ≤80µmol/l. METHODS: A retrospective review of our PUV database was performed. Age, intervention, and highest recorded random clinic urine osmolality (>1year) with concurrent plasma creatinine were recorded (normal urine osmolality 500-850 mOsm/kg). Data are given as median values, analyzed by Mann-Whitney u-test, with P<0.05 deemed significant. MAIN RESULTS: Urine osmolality was available in 77 boys with PUV out of 125 in our series. Of these, 34 required subsequent intervention (e.g., Mitrofanoff procedure, bladder augmentation). Age at testing trended towards being higher in the intervention group [7.9 (4.3-10.9) years vs. nonintervention 6.3 (4-8.4); P=0.06]. Urine osmolality was significantly reduced in the intervention group [411(293-547) vs. 631 (441-805) mOsm/kg; P<0.001]. Subgroup analysis comparing only those with creatinine ≤80µmol/l was respectively 451 (322-567) mOsm/kg (n=22) vs. 645 (469-810) mOsm/kg (n=40), P<0.01. CONCLUSION: This study confirms that hypoosmolar urine is highly associated with progression of LUT dysfunction, requiring intervention. Even boys with normal creatinine values have a greater risk of LUT deterioration if they have a RTD and produce hypoosmolar urine. LEVEL OF EVIDENCE: IV (retrospective service development project).

What effect do different 200 µm laser fibres have on deflection and irrigation flow rates in a flexible ureterorenoscope?

The objective of the study is to evaluate the reduction in flow and scope deflection of four leading 200-µm marketed laser fibres (Boston Scientific Flexiva™ 200, Boston Scientific Flexiva™ Trac Tip 200, Lumenis SlimLine™ EZ200 and Optical Integrity ScopeSafe™) via a flexible ureterorenoscope. A laboratory-based bench test was performed using a Flex X2™ flexible ureterorenoscope. Mean upward/downward deflection angles and flow rates (ml/min) for each fibre were calculated and compared to a control. The Optical Integrity ScopeSafe™ fibre has the least loss of deflection, losing only 8 % upward and 6 % downward deflection. Deflection loss was significantly less with this fibre compared to all other fibres (p < 0.0001). Mean flow rates were significantly greater with the Optical Integrity ScopeSafe™ laser fibre at 23 ml/min (p < 0.0001). Despite all fibres marketed as 200 µm, the deflection and flow properties show marked variations. The Optical Integrity ScopeSafe™ 200-µm laser fibre offers the best overall performance with significantly improved flow rates and the least loss of scope deflection.

Ureteroscopy and stones: Current status and future expectations.

Urolithaisis is becoming an ever increasing urological, nephrological and primary care problem. With a lifetime prevalence approaching 10% and increasing morbidity due to stone disease, the role of ureteroscopy and stone removal is becoming more important. We discuss the current status of stone disease and review the ever increasing role that ureteroscopy has to play in its management. We discuss technological advances that have been made in stone management and give you an overview of when, how and why ureteroscopy is the most common treatment option for stone management. We touch on the role of robotic ureteroscopy and the future of ureteroscopy in the next 10 years.

Proposition for new terminologies in PCNL: what does 'ultra-mini-micro' actually mean?

Ever smaller miniaturised techniques are being developed for percutaneous nephrolithotomy (PCNL), with access sheaths now as small as 4.8Fr being used in adults. With the ever expanding use of the terms "micro" "mini" or "ultra" techniques, the terminology can be somewhat confusing. We propose a simple classification system to standardise the terminology for PCNL, encapsulating technological and procedural advancements.