BackgroundIrrigation and instrumentation during ureterorenoscopic procedures may cause increased pressure in the renal pelvis (PP) with potential harmful adverse effects. In order to assess the pressure increases during ureterorenoscopy, we measured the intraluminal renal pelvic pressure during retrograde intrarenal stone surgery (RIRS).MethodsTwelve patients admitted for RIRS were included. Irrigation rate was standardized to 8 ml/min. A ureteral catheter was retrogradely placed in the renal pelvis for PP measurements. PP was measured one time per second during insertion of the Storz Flex-X2 ureteroscope and during stone treatment.ResultsBaseline PP was mean 10(±4.0) mmHg. During simple ureterorenoscopy, PP was mean 35(±10) mmHg. During stone management the average PP was 54(±18) mmHg and pelvic pressure peaks up to 328 mmHg occurred. In a 5-min standardized period of simple ureterorenoscopy, 83 pressure peaks >50 mmHg were measured in average per patient (range 2–238). Forced irrigation with a 20 ml syringe resulted in pressure peaks up to 288 mmHg.ConclusionVery high pelvic pressures are obtained during flexible ureterorenoscopy. Taking into consideration that the threshold for pyelovenous backflow is around 30 mmHg, it is concerning that PPs >300 mmHg are not uncommon during these procedures. Methods to monitor and lower the PP during ureterorenoscopy, therefore, are considered of importance.

Cystinuria continues to be one of the most challenging stone diseases. During the latest decades our knowledge of the molecular basis of cystinuria has expanded. Today 160 different mutations in the SLC3A1 gene and 116 in the SLC7A9 gene are listed. The full implications of type A, B or AB status are not yet fully understood but may have implications for prognosis, management and treatment. Despite better understanding of the molecular basis of cystinuria the principles of recurrence prevention have remained essentially the same through decades. No curative treatment of cystinuria exists, and patients will have a life long risk of stone formation, repeated surgery, impaired renal function and quality of life. Therapy to reduce stone formation is directed towards lowering urine cystine concentration and increasing cystine solubility. Different molecules that could play a role in promoting nucleation and have a modulating effect on cystine solubility may represent new targets for cystinuria research. Investigation of newer thiol-containing drugs with fewer adverse effects is also warranted. Determining cystine capacity may be an effective tool to monitor the individual patient's response. Compliance in cystinuric patients concerning both dietary and pharmacological intervention is poor. Frequent clinical follow-up visits in dedicated centres seem to improve compliance. Cystinuric patients should be managed in dedicated centres offering the complete range of minimal invasive treatment modalities, enabling a personalized treatment approach in order to reduce risk and morbidity of multiple procedures.

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