Editing Ureteric Stricture Disease

*'''Evaluation and treatment of ureteral strictures is essential to preserve renal function and rule out presence of malignancy'''

== Etiology ==
*'''<span style="color:#ff0000">Classification: benign vs. malignant</span>'''
====Benign====
*'''<span style="color:#0000ff">SIIRRII PUF (8):</span>'''
#'''<span style="color:#0000ff">S</span><span style="color:#ff0000">tones</span>'''
#'''<span style="color:#0000ff">I</span><span style="color:#ff0000">nstrumentation, endoscopic</span>'''
#'''<span style="color:#0000ff">I</span><span style="color:#ff0000">nfection (tuberculosis)</span>'''
#'''<span style="color:#0000ff">R</span><span style="color:#ff0000">enal ablation injury</span>'''
#'''<span style="color:#0000ff">R</span><span style="color:#ff0000">adiation</span>'''
#'''<span style="color:#0000ff">I</span><span style="color:#ff0000">schemia</span>''' (trauma, surgical dissection)
#'''<span style="color:#0000ff">I</span><span style="color:#ff0000">diopathic</span>'''
#'''<span style="color:#0000ff">P</span><span style="color:#ff0000">eri</span><span style="color:#0000ff">U<span style="color:#ff0000">reteral </span><span style="color:#0000ff">F<span style="color:#ff0000">ibrosis caused by abdominal aortic aneurysm or endometriosis</span>'''
#*Endometeriosis
#**Most patients with ureteral obstruction associated with endometriosis are asymptomatic
#***Signs and symptoms may occur cyclically and include flank pain, dysuria, urgency, hematuria and frequent urinary tract infections.
#**Management
#***A trial of hormonal therapy using gonadotropin-releasing hormone agonists (Lupron) or medroxyprogesterone (Danazol) should be initiated for mild symptomatic obstruction when there is good preservation of renal function.
#***For more severe obstruction associated with significant periureteral fibrosis, surgical intervention to correct the obstruction, with or without hysterectomy and bilateral salpingo-oophorectomy, is recommended
*'''Hysterectomy accounts for over 50% of iatrogenic ureteral injuries'''
**Most likely areas where the ureter can be occluded during hysterectomy (2):
**#Level of the broad ligaments
**#At the vaginal cuff and bladder trigone
====Malignant====
*'''<span style="color:#ff0000">Intrinsic: e.g. urothelial carcinoma</span>'''
*'''<span style="color:#ff0000">Extrinsic: e.g. cervical cancer</span>'''
==Diagnosis and Evaluation==
*'''<span style="color:#ff0000">The renal unit should be assessed for function before starting treatment because endourologic therapies require 25% function of the ipsilateral moiety to have reasonable success rates</span>''' (Figure 49-34 suggests 20%)
*'''<span style="color:#ff0000">The presence of obstruction on CT can identify ureteral stricture disease, but antegrade or retrograde pyelogram, CT urography, or diagnostic ureteroscopy is necessary to define the location and length of the ureteral stricture</span>'''
==Management==

=== <span style="color:#ff0000">Options (3):</span> ===
#'''<span style="color:#ff0000">Decompression</span>'''
#'''<span style="color:#ff0000">Endourological procedures (balloon dilation or endoureterotomy)</span>'''
#'''<span style="color:#ff0000">Surgical repair</span>'''
====Decompression====
*'''<span style="color:#ff0000">Ureteral stent placement</span>'''
**Effective acutely in treating most ureteral strictures, particularly intrinsic ureteral strictures.
**'''Patients with extrinsic ureteral compression eventually require percutaneous drainage or surgical management'''
**'''The use of tandem ureteral stent placement (two parallel stents) has been shown to be effective in benign and malignant extrinsic ureteral obstruction'''
**'''Placement of a ureteral stent in an obstructed system will result in decreased ureteral contractility'''
**No clear consensus regarding the benefits of metallic stents
====Endourologic procedures====
*'''<span style="color:#ff0000">Best management for ureteral strictures < 2 cm with no previous intervention is an endoscopic approach</span>'''
*'''<span style="color:#ff0000">Contraindications (1):</span>'''
*#'''<span style="color:#ff0000">Strictures >2cm</span>''' because dilation alone is unlikely to be successful
*'''<span style="color:#ff0000">Options (2): balloon dilation or endoureterotomy</span>'''
**'''<span style="color:#ff0000">Balloon dilation'''
***After 10 minutes of tamponade, the balloon is deflated and withdrawn. An internal stent is passed over a guidewire still in place, which is left indwelling for 2-4 weeks.
***'''Follow-up diuretic renography''' is usually performed ≈1 month after stent extraction and at 6- to 12-month intervals thereafter
***Success rates range from 50-76%, long-term outcomes are unfavorable
***'''Best results obtained in patients with iatrogenic, non-anastomotic strictures such as those secondary to ureteroscopic instrumentation'''. In that setting, a success rate of 85% was achieved compared with a rate of 50% for anastomotic strictures
**'''<span style="color:#ff0000">Endoureterotomy'''
***'''<span style="color:#ff0000">The position for the incision is chosen as a function of the level of the ureter involved. In general</span>'''
****'''Lower ureteral strictures are incised in an anteromedial direction to stay away from the iliac vessels'''
****'''Upper ureteral strictures are incised laterally or posterolaterally'''
***The incision can be performed using a cold knife, a cutting electrode, or a holmium laser
====Surgical repair====
=====Ureteroureterostomy=====
*So-called end-to-end repair
*'''<span style="color:#ff0000">Bridges ureteral defect of 2-3cm</span>'''
*'''<span style="color:#ff0000">Most appropriate for a short defects</span>''' '''<span style="color:#ff0000">(2-3cm)</span>''' '''<span style="color:#ff0000">involving the upper ureter or mid-ureter,</span>''' either in the form of stricture or as a consequence of recent injury
**'''<span style="color:#ff0000">Only short defects should be managed by end-to-end ureteroureterostomy</span>''' because tension on the anastomosis almost always leads to stricture formation
**'''<span style="color:#ff0000">Lower ureteral strictures are usually best managed by ureteroneocystostomy with or without a psoas hitch or Boari flap.</span>'''
*Success rate for a tension-free, watertight ureteroureterostomy is > 90%
*'''Technique'''
**In an open surgical approach, the choice of surgical incision depends on the level of the ureteral stricture
**'''Place stay stitches:''' Use 3-0 silk to place stay stitches at 12 o'clock on proximal and distal ureter, a few cm away from the cut ends. This will facilitate orientation. These will be removed later.
**'''Spatulate ureters:''' Use scissors to spatulate both ureters for 1-1.5 cm. Spatulate proximal ureter at 6 o'clock and distal ureter at 12 o'clock, using the silk stay sutures to guide orientation.
**'''Posterior anastomosis:''' Use 4-0 absorbable monofilament suture (e.g. monocryl or PDS) to take an outside-in bite on proximal ureter at one corner of cut apex at 6 o’clock and then take corresponding inside-out bite on distal ureter just lateral to 6 o’clock. Tie stitch, cut tail, and place needle on rubber-shod clamp. Repeat bite on opposite side of cut apex at 6 o'clock and place needle on rubber-shod clamp.
**'''Insert double J stent'''. Advance guidewire through proximal ureter into renal pelvis. Advance double J stent over guidewire and remove wire when stent in renal pelvis (meets resistance). To pass the distal end of the stent into the bladder, cut a side hole in the stent, and then pass the floppy end of the wire into the bladder and the firm end of the wire through the distal end of the stent and through the previously cut hole in the midportion of the stent. Advance the stent over the wire into the bladder and remove the wire.
**'''Anterior anastamosis:''' Use 4-0 absorbable monofilament suture (e.g. monocryl or PDS) and place a U stitch at 12 o’clock: take an outside-in bite at 12 o’clock on the proximal ureter followed by inside-out bite on distal ureter just lateral to 12 o’clock apex, then outside-in bite on distal ureter on contralateral side of 12 o’clock apex, then corresponding inside-out on the proximal ureter. Tie this down, cut needle, and leave each suture side long.
**'''Complete anastamosis:''' Use previous 4-0 absorbable monofilament sutures on shods and run each stitch anteriorly. Consider backhand for first bite at on corners. Once completed to 12 o'clock, tie to long tails from U suture. Cut tails.
***'''If tissue quality is tenuous, interrupted anastomosis is recommended'''
****Interrupted anastomosis allows more precise closure and ensures that the entire repair is not in jeopardy if a single area becomes compromised because of poor tissue quality, delayed ischemia, or an inadequate bite during the suturing.
****With interrupted anastomosis, keep tail long as handles for subsequent stitch and cut them after stitch next to it is placed.
**'''Remove silk stay sutures.'''
**'''Insert surgical drain'''
**'''Postoperative care'''
***'''Foley catheter is usually left indwelling for 1 to 2 days.'''
***'''Surgical drain may be removed if there is minimal output for 24 to 48 hours.'''
****If the surgical procedure is not performed entirely in a retroperitoneal manner, it is important to determine the nature of the fluid from the surgical drain by checking the creatinine level of the fluid. If there is no urinary extravasation, the drain can then be removed.
***'''The double-J ureteral stent is usually removed 4-6 weeks postoperatively'''
'''Ureterocalycostomy'''
*'''Ureteral stump is sewn end-to-side into an exposed renal calyx'''
*'''Rarely used; <span style="color:#ff0000">used where there is profound damage to the renal pelvis and UPJ</span>'''
=====Ureteroneocystotomy=====
*'''<span style="color:#ff0000">Appropriate for injury or obstruction affecting 3-4 cm the distal of the ureter</span>'''
*'''<span style="color:#ff0000">Bridges ureteral defect of 4-5cm</span>'''
**'''After adequate proximal ureteral mobilization, direct ureteroneocystostomy is performed only if a tension-free anastomosis is possible. Otherwise, a psoas hitch or Boari flap should be used as an adjunct.'''
*'''Technique:'''
**'''Approaches: intravesical, extravesical, or through a combination of the two'''
**Anastomosis can be tunneled or non-tunneled
***A direct, non-tunneled anastomosis may be performed if postoperative reflux is acceptable
****In a retrospective review, '''no significant difference in the preservation of renal function or risk of stenosis was found between refluxing versus anti-refluxing procedures.''' '''However, it is unclear if a non-refluxing anastomosis increases the risk of pyelonephritis in an adult patient'''
**'''Extravesical ureteroneocystomy[https://pubmed.ncbi.nlm.nih.gov/20620446/]'''
***'''Cystotomy:''' Use cautery to make 1-1.5 cm vertical incision on anterior surface of bladder. Use 4-0 chromic to take inside out bites at 4 quadrants of the cystotomy. Apply snaps to these.
***'''Spatulate ureter'''. Use scissors to spatulate the ureter for 1-1.5 cm at 6 o'clock.
***'''Cephalad vesicoureteric anastomosis'''. Use 3-0 absorbable monofilament suture (e.g. monocryl or PDS) to take an outside-in bite on the bladder at the cephalad aspect of the cystotomy and then inside-out on one side of 6 o'clock apex of distal ureter. Use another 3-0 absorbable monofilament suture (e.g. monocryl or PDS) and repeat on contralateral side of cephalad aspect of cystotomy. Tie these down, cut end without needle, place needle end on shod.
***'''Insert double J stent'''. Advance guidewire through ureter into renal pelvis. Advance double J stent over this, remove guidewire , and allow distal curl to fall into bladder.
***'''Caudal vesicoureteric anastomosis'''. Use 3-0 absorbable monofilament suture (e.g. monocryl or PDS) and place a U stitch at 12 o'clock of ureter to caudal aspect of cystotomy: take an outside-in bite at 12 o'clock on the ureter followed by inside-out bite on caudal aspect of the cystotomy, then outside-in bite on caudal aspect of the cystotomy just opposite to previous bite, then inside-out on the opposite side at 12 o'clock on the ureter. Tie this down, cut needle off, and leave suture side long.
***'''Complete vesicoureteric anastomosis'''. Use previous 3-0 absorbable monofilament sutures at apex and run each stitch distally. First bite is outside-in on ureter, second bite is backhand inside-out on bladder. Then subsequent bites are forehand outside-in on ureter, inside out on bladder. Once at the caudal end of anastomosis, tie to previous long 3-0 vicryl U sutures. Cut sutures.
***'''Insert surgical drain'''
=====Psoas hitch=====
*'''An effective method to bridge a defect of the lower third of the ureter.'''
*'''<span style="color:#ff0000">Bridges ureteral defect of 6-10cm (other source says 5-8cm[https://pubmed.ncbi.nlm.nih.gov/23759011/])</span>'''
**Can provide up to 5 cm of additional length compared to simple ureteroneocystostomy
**May be preferred over ureteroureterostomy in lower ureteral injuries because the tenuous ureteral blood supply might not survive transection.
**'''<span style="color:#ff0000">A ureteral defect extending proximal to the pelvic brim usually requires more than a psoas hitch alone</span>'''
*'''<span style="color:#ff0000">Contraindications (1):</span>'''
**'''<span style="color:#ff0000">A small, contracted bladder with limited mobility</span>'''
*'''Technique[https://pubmed.ncbi.nlm.nih.gov/23759011/]'''
**'''Identify the ureter.''' The ureter can be identified medial to the medial umbilical ligament (contains obliterated umbilical ligament) or anterior to the bifuctation of the common iliac artery.
**'''Mobilize the ureter.''' Encircle the ureter with a vessel loop to facilitate traction. Mobilize the ureter distally and proximally. Care must be taken to preserve the periureteric adventitial tissue with its inherent blood supply of the ureter. Ligate and transect the ureter distally, and if being performed for ureteric mass or fistula, ligate and transect the ureter proximally above area of concern. For ureteric mass, send frozen section from the cut edge of the proximal ureter. Place a stay suture at 12 o'clock to facilitate orientation.
**'''Mobilize the bladder.''' Fill the bladder with 200-300 mL of saline via the foley catheter. Dissect the peritoneum off the bladder. Depending on the length of the remaining proximal ureter, further bladder mobilization can be obtained by dividing the median umbilical ligament (urachus) and ipsilateral medial umbilical ligament. Additional mobility can be achieved by dividing the contralateral superior vesical artery.
***'''Aim is to allow a tension-free fixation of the bladder to the psoas muscle at least 2-3cm above the common iliac vessel.'''
**'''Cystotomy:''' Place two stay sutures, 4-5cm apart, in a oblique orientation such that the medial stay suture is more superior. Make a 4-5cm oblique incision between the stay sutures.
**'''Evaluate bladder tension:''' Use index finger inside the open bladder to elevate the ipsilateral most cranial aspect of the bladder. Check if the raised flap easily reaches the intended point of fixation at the psoas muscle. If the bladder cannot be brought to the psoas muscle without tension, the oblique bladder incision is extended to obtain a longer bladder flap.
**'''Fixation of bladder to psoas:''' Use two to three 3-0 absorbable monofilament sutures to take whole detrusor muscle thickness without mucosa and placed preferentially through the tendon of the psoas muscle above the common iliac artery and the femoral branch of the genitofemoral nerve.
***'''Care should be taken to avoid injury to the genitofemoral nerve and the femoral nerve'''
**'''Ureteroneocystotomy.'''
**'''Insert stent.'''
**'''Bladder closure.'''
**'''Insert surgical drain'''
*'''Complications'''
**'''Occur uncommonly'''
**'''Early'''
***'''Nerve injury'''
****'''<span style="color:#ff0000">Femoral nerve is most likely to be injured during a psoas hitch</span>'''
***'''Bowel injury'''
***'''Iliac vein injury'''
***'''Urosepsis'''
**'''Late'''
***'''Urinary fistula'''
***'''Ureteral obstruction'''
*'''Relative to the Boari flap, the advantages of psoas hitch include:'''
*#'''Increased technical simplicity'''
*#'''Decreased risk of vascular compromise'''
*#'''Decreased risk of voiding difficulties'''
=====Boari flap=====
*'''A pedicle of bladder is swung cephalad and tubularized to bridge the <span style="color:#ff0000">a 10-15-cm</span> gap to the injured ureter''' [Campbell's table says 12-15cm but text says 10-15cm]; '''a spiraled bladder flap can reach the renal pelvis in some circumstances, especially on the right side'''. Care should be taken to ensure adequate vascular supply to the flap
*'''<span style="color:#ff0000">A small bladder capacity is likely to be associated with difficult or inadequate Boari flap creation, warranting consideration of alternative methods in the preoperative surgical planning</span>'''
*'''<span style="color:#ff0000">The ratio of flap length to base width should be ≤ 3:1</span> to help minimize flap ischemia'''
=====Renal descensus=====
*'''Renal mobilization can provide additional length to bridge a defect in the upper ureter or decrease tension on a ureteral repair'''
*'''Bridges ureteral defect of 5-8cm'''
*After entry to the Gerota fascia, the kidney is completely mobilized and rotated inferiorly and medially on its vascular pedicle. The lower pole of the kidney is then secured to the retroperitoneal muscle using several absorbable sutures. Up to 8 cm of additional length may be gained using this technique.
=====Transureterostomy=====
*Transposing the injured ureter across the midline and anastomosing it end-to-side into the uninjured ureter
*'''Most often performed as a secondary or delayed procedure'''
*'''<span style="color:#ff0000">Absolute contraindications (1):</span>'''
*#'''<span style="color:#ff0000">Insufficient length</span> of the donor ureter to reach the contralateral recipient ureter'''
*'''<span style="color:#ff0000">Relative contraindications (5):'''
*#'''<span style="color:#ff0000">History of nephrolithiasis</span>'''
*#'''<span style="color:#ff0000">Urothelial malignancy</span>'''
*#'''<span style="color:#ff0000">Retroperitoneal fibrosis</span>'''
*#'''<span style="color:#ff0000">Chronic pyelonephritis</span>'''
*#'''<span style="color:#ff0000">Abdominopelvic radiation</span>'''
*#*'''Any disease process that may affect both ureters represents a relative contraindication'''
*'''<span style="color:#ff0000">Reflux to the recipient ureter, if present, needs to be identified and corrected simultaneously. Therefore, a voiding cystogram should be performed preoperatively, in addition to any other imaging</span>'''
*'''A tunnel under the sigmoid colon mesentery is created proximal to the inferior mesenteric artery''' to avoid ureteral tethering by this vessel; the donor ureter is then brought through the tunnel to the recipient side.
*The injured ureter becomes subsequently difficult to intubate or image with ureteroscopy through the bladder; ureteral access needs to be provided by a nephrostomy placed on the injured side.
*Caution is required while performing this procedure because it involves surgery on the uninjured, contralateral ureter with the theoretical risk for converting unilateral ureteral injury into bilateral ureteral injury. '''<span style="color:#ff0000">Instead of transureteroureterostomy, ileal interposition or ureteroureterostomy with renal mobilization, if necessary, are preferred.</span>'''
=====Ileal ureter substitution=====
*'''Reconstruction of the ureter with urothelium-based tissue is most preferable because it is not absorptive and is resistant to the inflammatory and potentially carcinogenic effects of urine. Incorporation of other tissue is reserved for situations in which a defect cannot be bridged by other methods.'''
*Delayed ureteral repairs, especially when a very long segment of ureter is destroyed, can be performed by creation of a '''ureteral conduit out of ileum''' in much the same way that an ileal conduit is constructed to drain the urine after cystectomy.; appendix and fallopian tube have been found to be unreliable ureteral substitutes.
*'''When an isoperistaltic segment of ileum is directly anastomosed to the bladder, reflux and renal pelvic pressure increase are usually seen only during voiding.''' The retrograde transmission of intravesical pressure is dependent on the length of ileum segment used in interposition and the voiding pressure
*'''Only 12% of patients with normal preoperative renal function developed significant metabolic problems postoperatively, and preoperative renal function was identified to be an important prognostic factor'''
*'''<span style="color:#ff0000">Not recommended in the acute setting</span>'''
*'''<span style="color:#ff0000">Contraindications (4):</span>'''
*#'''<span style="color:#ff0000">Baseline renal insufficiency</span> (creatinine > 2 mg/dL)'''
*#'''<span style="color:#ff0000">Inflammatory bowel disease</span>'''
*#'''<span style="color:#ff0000">Radiation enteritis</span>'''
*#'''<span style="color:#ff0000">Bladder dysfunction or outlet obstruction</span>'''
*Before the surgical procedure, a full mechanical and antibiotic bowel preparation is often used
*The length of the ureteral defect is measured, and an appropriate segment of distal ileum is chosen. The segment should be ≥15 cm away from the ileocecal valve
*In the presence of a scarred or intrarenal pelvis, ileocalicostomy may be performed
*Patients with worsening metabolic abnormalities associated with a progressively dilating ileal ureter should be evaluated for vesicourethral dysfunction.
*'''<span style="color:#ff0000">Malignancy arising from an ileal ureter segment has been reported and it is recommended that regular endoscopic examination be performed starting at postoperative year 3 for early detection</span>'''
=====Other interposition=====
*'''<span style="color:#ff0000">Short segments of small or large bowel are formed into a long, thin tube (Monti procedure)</span>'''
*'''<span style="color:#ff0000">Appendix has also been used</span>'''
=====Autotransplantation=====
*Generally, '''considered when the contralateral kidney is absent or poorly functioning or when other methods for ureteral substitution or repair are not feasible'''
*'''Final option before nephrectomy'''
*'''<span style="color:#ff0000">Not recommended in the acute setting</span>'''
==Ureteroenteric anastomotic stricture==
*'''Rates of ureteroenteric anastomotic stricture after continent diversion is 3-25%, majority occur within the first 2 years'''
*'''Most patients with a long-term urinary conduit will have an element of chronic hydronephrosis that is not secondary to obstruction; obstruction suggested by a decrease in renal function or loss of reflux on a routine loopogram should prompt diuretic renography to quantitatively assess for functional obstruction'''
*'''Factors predicting stricture after ureteroenteric anastomosis:'''
*#Technique used for ureteral dissection
*#Segment of bowel used for the diversion
*#'''Type of anastomosis performed'''
*#*'''Risk of stricture is less in refluxing anastamoses compared to non-refluxing anastamoses and therefore the use of a reflexing anastamosis is preferred for continent reservoirs (note that there is no difference in risk of stricture for ureteroneocystotomy)'''
*#'''Side of anastomosis'''
*#*'''Higher incidence of stricture formation on the left'''
*#**When performing an ileal conduit, the left ureter is brought underneath the sigmoid mesentery just overlying the aorta. The additional length and dissection needed on the left and the possibility of angulation around the inferior mesenteric artery may lead to increased risk of stricture on the left side
===Management===
*'''See Figure in Campbell's'''
*'''Antegrade endourologic management of ureteroenteric or ureterocolic strictures is preferred''', unlike the management of ureteral strictures
*'''Strictures > 2cm or on the left are less likely to succeed with endourologic management'''
**Endourologic success rate for
***Strictures > 1cm is 6% vs. 50% strictures < 1 cm
***Left sided-stricture 19% vs. 41% on the right
****No difference was noted in sidedness with open repair
*'''Although long-term patency of minimally invasive procedures for ureteroenteric strictures is in the range of 50%, such approaches are still used as the initial intervention''', reserving operative management for those patients in whom endourologic intervention fails and for patients with strictures > 1 cm
*'''When considering endoscopic incision of a left ureteroenteric stricture, the risk of hemorrhage is a consideration because the sigmoid mesentery can be in close proximity. This, taken with the lower success rates of all endoscopic approaches on the left side, supports serious consideration for primary repair when treating left ureteroenteric anastomotic strictures'''
===Retrocaval ureter===
*'''See Pediatrics Ureter Anomalies Chapter Notes'''
==Questions==
#What are the causes of ureteral stricture disease?
#What are the management options for ureteral stricture disease?
#What are the contraindications to transureterostomy?
#What investigations are needed before considering transureteroureterostomy?
#What are the contraindications to ileal ureter substitution?
#What is the preferred approach (retrograde vs. antegrade) for the endoscopic management of ureteroenteric stricture?
#What are the risk factors for failure of endourological management of a ureteroenteric anastamostic stricture?
==Answers==
#What are the causes of ureteral stricture disease?
##Stones
##Instrumentation, endoscopic
##Infection (TB)
##Radiation
##Renal ablation injury
##Ischemia
##Idiopathic
##Periureteral fibrosis
#What are the management options for ureteral stricture disease?
##Diversion
##Endoscopic
##Surgical
###Ureteroureterostomy
###Ureteroneocystotomy
###Psoas hitch
###Boari flap
###Renal descensus
###Transureteroureterostomy
###Ileal ureter
###Autotransplant
#What are the contraindications to transureterostomy?
##Absolute: insufficient length of ureter
##Relative: history of stones, upper tract cancer, RPF, radiation, chronic pyelonephritis, any process that affects both ureters
#What investigations are needed before considering transureteroureterostomy?
##VCUG to rule out reflux
#What are the contraindications to ileal ureter substitution?
##Baseline renal insufficiency
##Bladder dysfunction or outlet obstruction
##Inflammatory bowel disease
##Radiation enteritis
#What is the preferred approach (retrograde vs. antegrade) for the endoscopic management of ureteroenteric stricture?
##Antegrade
#What are the risk factors for failure of endourological management of a ureteroenteric anastamostic stricture?
##Left sided stricture
##Stricture > 1cm
==References==
*Wein AJ, Kavoussi LR, Partin AW, Peters CA (eds): CAMPBELL-WALSH UROLOGY, ed 11. Philadelphia, Elsevier, 2015, chap 49