Papworth Hospitals NHS Trust, Papworth Everard, East of England Deanery, UK
Department of Urology, Peterborough City Hospital, East of England Deanery, Bretton Gate, Peterborough, PE3 9GZ, UK
Improper drainage of urine through the upper urinary tract is a risk factor for the development of post renal acute kidney injury. This could be due to obstruction (of various causes) and requires urgent decompression of the ureter; in such situations ureteric stents or nephrostomy tubes can be inserted to relieve the pressure and pass debris until more definitive treatment can take place.
This chapter aims to guide the reader through ureteric stenting with an overview of indications, stent material, insertion technique, complications and some common issues faced with the procedure.
The Ureteric Stent
A ureteric stent is an endo-luminal catheter inserted into the ureter to re-establish or maintain patency secondary to obstruction. It can also be placed prophylactically prior to procedures/surgery to prevent obstruction, or after procedures/surgery to promote ureteral healing. The ideal stent is one that allows optimal flow while being tolerable by the patient. It should be biocompatible, clearly visible on radiological imaging, and easy to insert or remove. For long term use it ought to be resistant to infection, corrosion and encrustation.
Stents are available in a variety of shapes, length, diameter and material choice. The most commonly used stent is the 6 Fr Urethane Polymer ‘JJ’ (or pigtail stent ) 24–26 cm in length, though the exact choice of stent will vary depending on the patient’s height, ureteric anatomy and indication for the stent.
External compression of the ureter
Ureteral pathology requiring anatomoses i.e. ureterouretostomy
Prophylaxis (with surgery or procedures)
Internal obstruction within the ureter can occur secondary to clots, stones or strictures, whereas external compression of the ureter can occur secondary to retroperitoneal fibrosis (Ormond’s disease), tumours, pelvic collections, lymphadenopathy or pregnancy (with direct compression of the ureter by the foetus). These may be defined as uncomplicated or complicated (by infection, acute kidney injury, or renal failure). In those with complicated obstruction prompt decompression is required following placement of a retrograde ureteral stent (or nephrostomy tube).
Ureteral stents may also be indicated following ureteric pathology caused by trauma, strictures, malignancy or those iatrogenically induced, requiring a ureteroureterostomy (end to end ureteral anastomosis). The two ends are re-anastomosed over a ureteric stent.
Ureteral stents can be inserted prophylactically following ureteroscopy or extra-corporeal shockwave lithotripsy (especially in stones greater than 1.5 cm). Placement reduces the risk of oedema and subsequent obstruction i.e. steinstrasse, allowing for adequate drainage. Other examples include placement following pyelotomy, or placement of a ‘Bander stent’ during cystectomy to stent the ureter during uretero-ileal conduit constructions for a urostomy. They can also be placed prior to open surgery to dilate the ureter for identification if the operating site is significantly scarred from a previous surgery or dissection.
Stents are available in a variety of shapes, length, diameter and material choice (Fig. 4.1).
A JJ stent . Note the fenestrations along the shaft and in the pigtail of the stent
The most common shape is a ‘JJ’ (or pigtail) stent , owing to the curl of the stent both proximally and distally when in position (Fig. 4.1). There are multiple fenestrations along the pigtail and shaft of the catheter which improves drainage. Other stents include multi-length, noncurled, tail stents and spiral stents. It should be noted that the majority of the drainage occurs through the fenestrations of the stent rather than through it.
The diameter of the stent will vary from 4.7 Fr (the smallest that would fit over a typical guidewire diameter) up to 8 Fr. A larger diameter is preferred for cases of malignant compression or insertions following endopyelotomy. Alternatively two stents could be placed. The choice of length can be selected by either measurement of the patient’s height, visualisation under fluoroscopic guidance with a retrograde ureteropyelogram, or direct visualisation in open surgery. The presence of a pelvic or transplanted kidney will also affect length selection. The patient’s height may be more beneficial in cases of dilated and tortuous ureters as following stent deployment the ureter may shrink following urinary flow. As a rough guide:
Stent length (cm)
Patient height (m)
Greater than 1.85 m
Stent material can be of polymer or metal origin. Polymer stents are most commonly silicone but can be made out of polyurethane or other polymers. They are commonly coated in ‘hydrogel’ for ease of insertion/removal, reducing encrustation and improving biocompatibility. The polymer compounds are the gold standard in their strong advantage of being more inert than other substances including metal. However, the polymer stent has limitations in cases requiring more mechanical resistance such as extrinsic compressions from malignancy and there can be difficulty advancing in narrow or tortuous ureters.