Table 1.

Examples of different stent shapes

SINGLE J (SJ) The proximal end has a J shape, while the distal end goes directly outside the urethra. The distal end can be connected to a separate bag in order to monitor the different diuresis between the two kidneys.
DOUBLE J (DJ) Their name comes from the peculiar J shape of the proximal and distal end, that serves to avoid stent displacement [14]. Each coil usually has one end hole and four side holes, while the shaft may have multiple holes or no holes at all.
STRING STENT Strings are made of suture material; they run through the urethra and exit from the external urethral meatus [16]. The position of the strings makes the removal process easier [2,15, 16], reducing complication rates and stent-related symptoms (SRS) when removed in a short time.
TAIL STENT The loops of polymer on the distal end have been designed to reduce bladder irritation and obstructive urinary symptoms [14]. It is worth noting that these stents are not superior to DJ stents in reducing SRS [17].
PIGTAIL SUTURE STENT (PSS) 7 Fr x 16 cm stent with a distal 0.3 Fr double suture that reaches the bladder, reducing SRS. It is indicated in proximal stone-related obstruction, after stone treatment (URS - ureterorenoscopy/ureteroscopy), in case of ureteropelvic junction, stones and in strictures [18].
SPIRAL STENT First made up of a metal wire that maintains a stable opening of the ureteric lumen in case of extrinsic compression or blockage [14], they are now polymeric spirally cut stents that adapt to the ureter's shape [19].
MESH STENT Self-expanding stents created to reduce the irritation of the urinary tract and to facilitate the flow within the stent (when compared to JJ) [2]. Bioactive compounds can be eluted using mesh structure as a drug reservoir [14].
ANTI-REFLUX Anti-reflux membrane valve should reduce reflux and its related symptoms [10]. The valves can be made of two liplike membranes with an inner cavity, that functions as a fluidic channel and a pathway for insertion of guidewires [20].
MAGNETIC-TIPPED The magnetic end is composed of a stainless-steel bead that should make the removal procedure easier [2, 3]. The magnet at the distal coil of the ureter should also serve to prevent migration [10].