Stent placement can be useful for saving a kidney at risk for postrenal acute kidney failure due to the increased hydrostatic pressure, swelling and infection (pyelonephritis and pyonephrosis) caused by an obstructing stone. Ureteral stents vary in length from 24 to 30 cm (9.4 to 11.8 in) and most have a shape commonly referred to as a "double-J" or "double pigtail", because of the curl at both ends. They are designed to allow urine to flow past an obstruction in the ureter. They may be retained in the ureter for days to weeks as infections resolve and as stones are dissolved or fragmented by ESWL or by some other treatment. The stents dilate the ureters, which can facilitate instrumentation, and they also provide a clear landmark to aid in the visualization of the ureters and any associated stones on radiographic examinations. The presence of indwelling ureteral stents may cause minimal to moderate discomfort, frequency or urgency incontinence, and infection, which in general resolves on removal. Most ureteral stents can be removed cystoscopically during an office visit under topical anesthesia after resolution of urolithiasis.
Genetics
The cytogenetics of EHE gave some of the first clues of an underlying genetic alteration. A balanced, reciprocal translocation t(1;3)(p36.3;q25) in EHE tumor cells was first described by Mendlick et al. in 2001 (Mendlick MR, Nelson M, Pickering D, Johansson SL, Seemayer TA, Neff JR, Vergara G, Rosenthal H, Bridge JA (2001). "Translocation t(1;3)(p36.3;q25) is a nonrandom aberration in epithelioid hemangioendothelioma". Am. J. Surg. Pathol. 25 (5): 684–7. doi:10.1097/00000478-200105000-00019. PMID 11342784. {{cite journal}}:  CS1 maint: multiple names: authors list (link)). This led to the landmark paper by Tanas et al. in 2011(Tanas MR, Sboner A, Oliveira AM, Erickson-Johnson MR, Hespelt J, Hanwright PJ, Flanagan J, Luo Y, Fenwick K, Natrajan R, Mitsopoulos C, Zvelebil M, Hoch BL, Weiss SW, Debiec-Rychter M, Sciot R, West RB, Lazar AJ, Ashworth A, Reis-Filho JS, Lord CJ, Gerstein MB, Rubin MA, Rubin BP (2011). "Identification of a disease-defining gene fusion in epithelioid hemangioendothelioma". Sci Transl Med. 3 (98): 98ra82. doi:10.1126/scitranslmed.3002409. PMID 21885404. {{cite journal}}:  CS1 maint: multiple names: authors list (link)) describing the specific genes involved in the translocation associated with the most common forms of EHE. This alteration results in the fusion of genes coding for two transcription co-activators (transcriptional regulators): TAZ (transcriptional co-activator with PDZ-binding motif) also known as WWTR1 (WW domain-containing transcription regulator protein 1) and CAMTA1 (calmodulin-binding transcription activator 1). The names in parenthesis are not relevant to casual (or even science) readers but are included to help distinguish them from other genes.