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A ureteral stent (pronounced you-REE-ter-ul), or ureteric stent, is a thin tube inserted into the ureter to prevent or treat obstruction of the urine flow from the kidney. The length of the stents used in adult patients varies between 24 and 30 cm. Additionally, stents come in differing diameters or gauges, to fit different size ureters.
A ureteric balloon catheter is a balloon catheter intended for treating strictures of the ureter. In fact it is a double J stent on which a balloon is mounted. It is connected to a delivery device (pusher) to introduce it from the bladder into the ureter. The system comprises a non-return valve device, and a pusher with a stylet and two ports.
The French scale measures the outer diameter of the catheter, not the size of the internal drainage channel (inner diameter). For instance, a two-way catheter of 20 Fr and a three-way catheter of 20 Fr have the same outer diameter, but the three-way catheter has an additional channel for irrigation, reducing the size of its drainage channel.
A ureteric stent may be inserted to relieve an obstruction. [16] If the cause cannot be removed, a nephrostomy may be required, which is the insertion of a tube connected to the renal pelvis which directly drains urine into a stoma bag .
Inadequate ureteral length may also be encountered, leading to ureteral kinking and subsequent obstruction. If plastic tubes need inserting, their malposition can lead to obstruction and eventual breakdown of the opening (anastomosis). Anastomotic leak is the most frequently encountered complication.
The length of the adult kidney is normally 10–12 cm, and the right kidney is often slightly longer than the left kidney. The adult kidney size is variable due to the correlation with body height and age; however, normograms for pediatric kidney size are available. [1]
Balloon catheters are also utilized in the deployment of stents during angioplasty. Balloon catheters are supplied to the cath lab with a stent pre-mounted on the balloon. When the cardiologist inflates the balloon it expands the stent. When the cardiologist subsequently deflates the balloon, the stent stays behind in the artery and the balloon ...
A retrograde pyelogram may be performed to find the cause of blood in the urine, or to locate the position of a stone or narrowing, tumour or clot, as an adjunct during the placement of ureteral stents. [13] It can also be used ureteroscopy, or to delineate renal anatomy in preparation for surgery.