Management of ureteral strictures by different modalities and effect of stents on upper tract drainage

Mechanical characteristics of the ureter and clinical implications

The ureteric wall is a complex multi-layered structure. The ureter shows variation in passive mechanical properties, histological morphology and insertion forces along the anatomical length. Ureter mechanical properties also vary depending on the direction of tensile testing and the anatomical region tested. Compliance is greatest in the proximal ureter and lower in the distal ureter, which contributes to the role of the ureter as a high-resistance sphincter. Similar to other human tissues, the ureteric wall remodels with age, resulting in changes to the mechanical properties. The passive mechanical properties of the ureter vary between species, and variation in tissue storage and testing methods limits comparison across some studies. Knowledge of the morphological and mechanical properties of the ureteric wall can aid in understanding urine transport and safety thresholds in surgical techniques. Indeed, various factors alter the forces required to insert access sheaths or scopes into the ureter, including sheath diameter, safety wires and medications. Future studies on human ureteric tissue both in vivo and ex vivo are required to understand the mechanical properties of the ureter and how forces influence these properties. Testing of instrument insertion forces in humans with a focus on defining safe upper limits and techniques to reduce trauma are also needed. Last, evaluation of dilatation limits in the mid and proximal ureter and clarification of tensile strength anisotropy in human specimens are necessary.

[Long-term results for subcutaneous Detour® prosthesis for ureteral obstruction: experiences of implantation, aftercare and management of complications]

BACKGROUND

We present the long-term results of implementation of the Detour® prosthesis as an alternative to established methods of surgical, percutaneous or internal urinary diversion.

PATIENTS AND METHODS

Between 2004 and 2012 a total of 40 prostheses were implanted in 31 patients (mean age 65 years) with ureteral strictures of various origins. In the follow-up the patients underwent examinations and completed questionnaires.

RESULTS

The average follow-up was 23 months (range 1-92 months). Sonographic examinations showed no urinary retention in 38 out of 40 implanted systems. The retention values were stable in 19 patients, improved in 7 and worse in 3. The quality of life (QoL) was high (EORTC QLQ-C30 90%). Intraoperative complications were 2 intestinal lesions and 3 bleeding of the renal-pelvic system. Postoperative urinary tract infections and wound complications were encountered. In the long-term course three infected hydronephroses occurred which were treated and cured with antibiotics and temporary nephrostomy and 4 systems were explanted, including 2 exchanges.

CONCLUSIONS

The system may be considered for patients with ureteral strictures with palliative and curative intent. There were no significant disadvantages in comparison with established methods. There were fewer risks in implantation and complications were manageable. The quality of life was significantly improved.