Ureteric Stenting E-Book
116,99 €
Mehr erfahren.
- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
The only book dedicated to this important area of urology, Ureteric Stenting comprehensively reviews the entire topic, providing highly specialized advice to enable outstanding clinical management of patients. All aspects of ureteric stenting are covered, from basic to complex, giving urologists, nephrologists and trainees an authoritative and up-to-date guide on best clinical practice.
Sie lesen das E-Book in den Legimi-Apps auf:
Seitenzahl: 568
Veröffentlichungsjahr: 2017
Ähnliche
Table of Contents
Cover
Title Page
List of Contributors
Foreword
Preface
1 Anatomy of the Human Ureter
1.1 Structure
1.2 Blood Supply
1.3 Nerves
1.4 Embryology
1.5 Congenital Variations
1.6 Clinical Significance
References
2 Anatomic Variations of the Ureter
2.1 Horseshoe Kidney
2.2 Duplex Ureter
2.3 Megaureter
2.4 Ectopic Ureter
2.5 Ureterocele
References
3 The Pathophysiology of Upper Tract Obstruction
3.1 Introduction
3.2 Aetiology
3.3 Presentation
3.4 Diagnosis
3.5 Consequences of Obstruction
3.6 Post-Obstructive Outcomes
3.7 Summary
References
4 Physiology of the Human Ureter
4.1 Historical Introduction
4.2 The Pain and Myths of Ureteric Colic
4.3 Anatomical and Functional Studies
4.4 Ureteric Transport Mechanisms
4.5 Physiological and Pharmacological Properties of Human Ureteric Muscle
4.6 The Effect of Metoclopramide and Glucagon
4.7 The Effect of Prostaglandin Synthetase Inhibitors
4.8 The Effect of Acid-Base Changes Upon Ureteric Contractility
4.9 The Effects of Stents Upon Ureteric Function
References
5 Etiology of Ureteric Obstruction
5.1 Congenital Causes
5.2 Metabolic Causes
5.3 Neoplastic Causes
5.4 Inflammatory Causes
5.5 Miscellaneous Causes
5.6 Conclusion
References
6 The Role of the Interventional Radiologist in Managing Ureteric Obstruction
6.1 Introduction
6.2 Indications for Antegrade Stenting
6.3 Patient Preparation for Antegrade Stent Insertion
6.4 Stent Design
6.5 The One-Stage Antegrade Stent
6.6 The Rendezvous Procedure
6.7 Summary
References
7 Emergency Management of Ureteric Obstruction
7.1 Introduction
7.2 Identifying Patients with Obstructive Pyelonephritis
7.3 Outcomes by Drainage Modality
7.4 Comparative Effectiveness
7.5 Quality of Life (QOL)
7.6 Conclusions
References
8 The History and Evolution of Ureteral Stents
8.1 Introduction
8.2 History and Evolution of Stent Nomenclature
8.3 Ancient History
8.4 Recent History
8.5 Further Advances in Ureteral Stent Technology
References
9 Ureteral Stent Materials: Past, Present, and Future
9.1 Introduction
9.2 Materials
References
10 Physical Characteristics of Stents
10.1 Introduction
10.2 History
10.3 Standard
10.4 Long-Term Use (Metal)
10.5 Comfort/Convenience
10.6 Dissolvable Stent
10.7 Drainage
10.8 Anti-Reflux
10.9 Self-Expanding
10.10 Thermo-Expanding
10.11 Spiral Stent
10.12 Film-Anchoring Stent
10.13 Future Directions
References
11 Coated and Drug-Eluting Stents
11.1 Introduction
11.2 Stent Coatings
11.3 Drug-Eluting Stents
11.4 Conclusion
References
12 Coated and Drug-Eluting Ureteric Stents
12.1 Introduction
12.2 Drug-Eluting Metal Stents
12.3 Pharmaceutical Substances
12.4 Drug-Eluting Stents in Urology
12.5 Coated Metallic Stents
12.6 Conclusions
References
13 Ureteric Stents: A Perspective from the Developing World
13.1 Introduction
13.2 Pattern of JJ Stent Usage in India
13.3 Stent Types and Economics
13.4 Stent Tracking and Removal
13.5 Stent Register
13.6 Forgotten JJ Stents (Figures 13.1–13.3)
13.7 Why the Forgotten Stent is a Major Problem in India?
13.8 Trends in Management of Forgotten Stent
13.9 JJ Stents Outside the Ureter and Pelvicalyceal System
13.10 Tips and Tricks for the Management of Migrated and Misplaced Stents
13.11 Recommended Protocol for the Repositioning of Incorrectly Placed Stents
References
14 Ethical Issues in Ureteric Stenting
14.1 Clinical Presentation
14.2 Salvage Therapy Options
14.3 Patient Desire
14.4 Patient Status, Family and Social Issues
14.5 Ethical Issues in Benign Ureteric Obstruction
14.6 Role of Palliative Care Teams
14.7 A Multidisciplinary Approach
14.8 Other Considerations
14.9 Summary
References
15 Equipment and Technical Considerations During Ureteric Stenting
15.1 Introduction
15.2 Equipment
15.3 Tips and Tricks
15.4 Conclusion
References
16 Extra-Anatomic Stent Urinary Bypass
16.1 Introduction
16.2 Indications
16.3 Contraindications
16.4 The Paterson Forrester Stent
16.5 Stent Placement
16.6 Top End Aspect of Stent Insertion Procedure (Kidney Aspect)
16.7 Tunneling Procedure
16.8 Lower Aspect of Stent Insertion Procedure (Bladder Puncture)
16.9 The Technique of Stent Changes
16.10 Complications and How to Deal With Them
16.11 Future Developments
References
17 Detour Extra-Anatomical Ureteric Stent
17.1 Introduction
17.2 The Need for an Extra-Anatomic Drainage
17.3 Prerequisites for Extra-Anatomic Stenting
17.4 Experience with the Extra-Anatomic JJ Stent
17.5 Experience With the Detour Stent
17.6 Personal Experience with Detour Stent
17.7 The Technique
17.8 Alternative Techniques
17.9 Complications
References
18 Tandem Ureteral Stents
18.1 Introduction
18.2 Mechanism of Ureteral Stent Failure and Corrective Measures
18.3 Tandem Ureteral Stents
18.4 Technique
18.5 Limited Evidence
18.6 Cost Considerations
18.7 Conclusion
References
19 Biodegradable Ureteric Stents
19.1 Introduction
19.2 Material
19.3 Research
19.4 Temporary Ureteral Drainage Stent
19.5 Uriprene
19.6 Future Directions
19.7 Conclusion
References
20 Metallic Ureteric Stents
20.1 Introduction
20.2 Which Metal?
20.3 Other Metallic Ureteric Stents
20.4 Results
20.5 Cost
20.6 Current Status
References
21 Removal of Ureteric Stents
21.1 Introduction
21.2 The Technique of JJ Stent Removal
21.3 String on the Stent
21.4 Removal of Segmental and Metallic Stents
21.5 Other Stents
21.6 Technical Considerations
21.7 Removal of Migrated Ureteric Stents
21.8 Removal of Encrusted Stents
21.9 Ileal Conduit Stents
21.10 Antibiotic Prophylaxis
21.11 Other Considerations
References
22 Encrustation of Indwelling Urinary Devices
22.1 Bacterial-Associated Encrustation
22.2 Non-Bacterial Causes of Encrustation
22.3 Non-Bacterial Based Indwelling Device Encrustation
22.4 Preventing Encrustation of Indwelling Urinary Devices
22.5 Stent Coatings
22.6 Conclusions
References
23 Stent Migration
23.1 Introduction
23.2 Why Stents Migrate?
23.3 Where Do Stents Migrate?
23.4 Stent Length and Migration
23.5 Which Stents Migrate?
23.6 Etiology of Ureteric Stricture and Migration
23.7 Detection of Stent Migration
23.8 Management of Migrated Stents
23.9 Special Situations
23.10 Conclusions
References
24 Health-Related Quality of Life and Ureteric Stents
24.1 Introduction
24.2 Development of the Ureteric Stent Symptom Questionnaire (USSQ)
24.3 Data on HRQoL with Stents from Clinical Studies
24.4 Studies Comparing Pharmacological Interventions
24.5 Other Aspects of Ureteric Stents and HRQoL
24.6 Conclusions
References
25 Evidence Base for Stenting
25.1 Contemporary Use of Ureteric Stents in Endourology
25.2 Evidence-Based Medicine Primer
25.3 Randomized Controlled Trials
25.4 Meta-Analysis and Systematic Reviews
25.5 The Evidence for Treatment of Acute Infectious Obstruction
25.6 Ureteroscopy and Post-Procedure Stent Insertion
25.7 Tubeless Percutaneous Nephrolithotomy
25.8 Conclusion
References
26 Robotic Ureteric Reconstruction
26.1 Introduction
26.2 General Considerations
26.3 Ureteroneocystostomy
26.4 Psoas Hitch
26.5 Boari Flap
26.6 Ureteroureterostomy
26.7 Conclusion
References
27 Indwelling Ureteric Stents – Health Economics Considerations
27.1 Introduction
27.2 Health Economic Evaluations
27.3 Short-Term Application
27.4 Medium- to Long-Term Application: Chronic Obstructive Uropathy
27.5 Comparator Assessment: Nephrostomy and Stenting
27.6 Other/Miscellaneous Considerations
27.7 Conclusion
References
28 Ureteric Stents
Index
End User License Agreement
List of Tables
Chapter 03
Table 3.1 Etiology of upper urinary tract obstruction.
Table 3.2 Key events in unilateral ureteric obstruction (UUO).
Chapter 04
Table 4.1 Ureteric response to electrical stimulation. The effects of various agents upon the contractile response of human ureteric smooth muscle to electrical field stimulation.
Chapter 07
Table 7.1 Advantages and disadvantages of ureteral stent versus percutaneous nephrostomy for drainage of the obstructed kidney.
Chapter 09
Table 9.1 Biomaterials: Advantages and Disadvantages.
Chapter 12
Table 12.1 Summary of the clinical experience with coated metallic stents.
Chapter 17
Table 17.1 The results of the Detour stent group showing the outcomes of the stents according to whether draining to bladder, skin or conduit. The results refer to the number of patients rather than the number of stents.
Chapter 25
Table 25.1 Oxford Center for Evidence-Based Medicine.
Table 25.2 Types of randomized control trials.
Table 25.3 Reporting guidelines and quality assessment statements for across study designs.
Table 25.4 The essential components of the CONSORT.
Table 25.5 The PICOT framework.
Table 25.6 Systemic inflammatory response syndrome criteria.
Table 25.7 Trials comparing acute decompression techniques retrograde stent versus percutaneous nephrostomy tube insertion.
Table 25.8 Meta-analyses comparing ureteral stents versus no ureteral stents post ureteroscopy.
Table 25.9 Randomized control trials comparing outcomes for stented versus non-stented group.
List of Illustrations
Chapter 01
Figure 1.1 Anatomy of the ureter.
Figure 1.2 Blood supply of the ureter.
Figure 1.3 Histology of the ureter.
Figure 1.4 Ureter embryology, part one.
Figure 1.5 Ureter embryology, part two.
Figure 1.6 Horse-shoe kidney.
Figure 1.7 Retro-caval ureter.
Figure 1.8 Duplex ureter.
Chapter 03
Figure 3.1 Renal blood flow, GFR and tubular pressure during UUO.
Figure 3.2 Renal cell types involved in the pathogenesis and progression of obstructive nephropathy. ECM: extracellular matrix; EMT: epithelial to mesenchymal transition; TGF-
β
1: transforming growth factor-
β
1; TNF-: tumor necrosis factor-; ROS: reactive oxygen species.
Figure 3.3 Autocrine-reinforcing loops amplifying angiotensin II (ANG II) and tumor necrosis factor-
α
(TNF- α) signaling. NF-kB: nuclear factor kappa-light-chain-enhancer of activated B cells; ICAM-1: intercellular adhesion molecule-1; MCP-1: monocyte chemotactic protein-1; VCAM-1: vascular cell adhesion molecule-1.
Figure 3.4 Pathogenesis of renal tubular apoptosis in obstructive nephropathy. Ang II: angiotensin II; EGF: epidermal growth factor; iNOS: inducible NO synthase; ROS: reactive oxygen species; TRPC-1: transient receptor potential cationic channel-1.
Chapter 04
Figure 4.1
Top panel:
the effect of diclofenac sodium (10-5 M) upon the contractile response of human ureteric muscle to electrical field stimulation.
Bottom Panels:
the restoration of contractile activity in the presence of diclofenac sodium (10-5 M) by prostaglandin E2 (10-6 M), increasing external potassium concentration to 12 mM or prostaglandin F2 alpha (10-6 M).
Figure 4.2 The actions of prostaglandin E2 and F2 alpha upon the contractile response of human ureteric smooth muscle. The upper trace demonstrates the increase in phasic contraction to electrical field stimulation. The bottom tracings illustrate tonic contractions with episodes of spontaneous activity induced by prostaglandin F2 alpha and the augmentation in isometric force initiated by simultaneously increasing the external concentration of potassium. The preparation is not receiving electrical stimulation.
Figure 4.3 The effect of increasing the external potassium concentration from 4 to 48 mM upon the membrane potential, Em, of a single human ureteric muscle cell. The resting membrane potential was −61 mV in this experiment; the inside of the cell negative with respect to the outside.
Figure 4.4 A simultaneous record of membrane potential, Em, of a single human ureteric muscle cell and isometric tension from the preparation showing the effect of prostaglandin F2 alpha (3 x 10-6 M). A small reversible depolarisation (7 mV) of the membrane is measured. There is a small rise in resting tension. Following return to the normal superfusate, this contracture persisted and culminated in spontaneous contraction with a further more marked increase in muscle tone.
Figure 4.5 The response to extracellular acidosis by increasing superfusate pCO2. Upper trace, isometric force; lower trace, superfusate pH. The arrows mark the intervention. CO2 content of the equilibrating gas mixture was raised from 5–30%. Temperature 36 degrees C.
Figure 4.6 The relationship between superfusate pH and steady state phasic tension in isolated human ureteric muscle. Tension is expressed as a percentage of that measured in control solution, pH 7.36. Superfusate pH was altered by varying pCO2. Error bars represent SD of an observation, n = 13 pH 7.8; n = 24 pH 7.2; n = 20 pH 7.0; n = 17 pH 6.8. Temperature 36 degree C.
Chapter 06
Figure 6.1 6 French 22cm Flexima Ureteric Stent System. Boston Scientific, MA, USA. The Glidex Hydrogel Coating on stent requires activation by soaking in sterile water or saline prior to use. This is inserted over a 0.038/0.035in guidewire. The suture at the proximal end enables retraction to facilitate optimal positioning; this must be removed once appropriate placement is achieved. The stent pusher has a radio-opaque distal marker.
Figure 6.2 21-G introducer needle with stylet inserted into the mid pole calyx under ultrasound guidance. Satisfactory position confirmed with radiographic contrast. Midpole puncture may allow easier stent placement due to greater pushability particularly in the context of a distal ureteric stricture.
Figure 6.3 Lower pole puncture. 0.018in nitinol guidewire inserted to distal ureter and co-axial introducer, dilator and sheath inserted (tip of sheath has a radiographic marker lying in proximal ureter). The sheath accomodates both the 0.018in wire and a 0.035in standard wire, allowing the subsequent catheters and stents to be passed over the 0.035in wire, leaving the 0.018in wire in situ as a safety wire.
Figure 6.4 Catheter advanced into the bladder over a hydrophillic 0.035in wire and the approriate intravesical position confirmed with contrast.
Figure 6.5 A stiff 0.035in guidewire is positioned within the bladder and 5mm balloon dilatation of the distal ureter sticture secondary to muscle invasive transitional cell carcinmoma is performed to enable stent placement. Waisting of the distal 1/3
rd
of the balloon is noted at the level of the vesicoureteric junction.
Figure 6.6 Following satisfactory stent placement, a covering nephrostomy tube is placed. This is then removed under flouroscopic guidance following a nephrostogram, as is the authors’ normal practice.
Chapter 08
Figure 8.1 Patent activity for ureteral stents.
Figure 8.2 Silicone tube used by Zimskind as indwelling ureteral stents. Note the internal ureteral catheter used to support the silicon tube during cystoscopic insertion.
Figure 8.3 Stent pusher with radiopaque tip.
Figure 8.4 The original illustration of “Gibbon’s stent.”
Figure 8.5 The original “Double J” used by Finney. Note the “J” ends that are straightened by a guidewire.
Figure 8.6 The pigtail retentive coil.
Chapter 10
Figure 10.1 Resonance metallic ureteral stent.
Figure 10.2 Abdominal x-ray of resonance metallic ureteral stent.
Figure 10.3 Bard inlay ureteral stent (green) and stent pusher (orange).
Figure 10.4 Boston Scientific dual durometer stent.
Chapter 11
Figure 11.1 Encrusted distal curl of ureteral stent.
Chapter 12
Figure 12.1 Optical coherence tomography (OCT) images from the stented ureters of the same pig. The OCT images were obtained after 4 weeks of follow-up. The struts of the stent are presented as illuminating sites with shadows behind them (red arrows). The struts mark the border between the urothelium and muscular layer of the ureter for either pigs or rabbits. a) A characteristic OCT presentation of a ureter with an implanted conventional MS. The tissue between a strut of the stent and the ureteral lumen can be observed and the extensive hyperplastic reaction of the urothelium extends inside the lumen of the ureter and compromises patency (white line). b) A respective image from a ureter stented with drug-eluting stent (DES). Notice the clearly less hyperplastic reaction in comparison to the conventional MS (white line).
Figure 12.2 Ureter dilated by DEB and specimen removal after 24 h. a). The blue arrows show sites of reconstitution of the urothelial layer. The substantially less acute inflammation and granulation tissue formation are marked by the red arrows. H&E, 200x. b) Reconstitution of the urothelium and limited infammation (red arrow). H&E, 400x. c) Immunohistochemistry for paclitaxel and streptavidin-biotin peroxidase staining shows that paclitaxel is located in the superficial epithelial cells (yellow arrow) and in the muscularis propria (red arrow). The magnification used was 200x.
Chapter 13
Figure 13.1 Fifty-three-year-old gentlemen admitted with retained stent inserted for obstructive uropathy three years ago.
Figure 13.2 Retained stent for 10 years post open surgery for stone disease.
Figure 13.3a-f Thirty-four-year-old male with no comorbidities underwent left PCNL with DJ stenting 14 years ago, but DJ stent was not removed. SPCL with left PCN followed by laparoscopic left simple nephrectomy.
Figure 13.4 Extra anatomic placement of JJ stent.
Figure 13.5 Extra anatomic placement of JJ stent with bilateral nephrostomy.
Figure 13.6 Repositioned stents after stone removal.
Figure 13.7 Migrated stent with entangled wire.
Figure 13.8 Stent knotted with wire.
Figure 13.9 Twenty-five-year-old female with retained stent.
Figure 13.10 Retained encrusted stent in a 25-year-old female.
Figure 13.11 Stent placed into external iliac vein, IVC and right atrium.
Figure 13.12 Stent placed into external iliac vein, IVC and right atrium, intraoperative picture.
Figure 13.13 Heavy encrustation on a forgotten stent.
Chapter 15
Figure 15.1 Ureteral orifice, which has a “tent,” is more compliant.
Figure 15.2 Hydrophilic straight soft and stiff guidewires.
Figure 15.3 Different tips of guidewires.
Figure 15.4 a) Retrograde pyelography of a tortuous hydroureter. b) Advancement of a soft hydrophilic guidewire toward the ureteral loop and up to the renal pelvis. c) Advancement of the ureteral catheter into the renal pelvis. d) Changing the soft guidewire for a stiffer one will facilitate the realignment of the tortuous ureter.
Figure 15.5 Different tips of ureteral catheter.
Figure 15.6 Advantage of using a whistle tip ureteral catheter with a curve tip guidewire, particularly to facilitate ureteral cannulation even with a distal ureter hooked.
Figure 15.7 8/10 coaxial dilators.
Figure 15.8 a) Low opacity of the distal tip of the 10 F stylet into the distal ureter. b) Placement of a second guidewire into the 10F stylet.
Figure 15.9 Dual-lumen catheter.
Figure 15.10 Rocamed ureteral access sheath with two distal lumens usable.
Figure 15.11 Ureteral balloon dilator.
Figure 15.12 Different tips of KMP catheters. It could be helpful to place a guidewire into a ureter of a partial ureteral duplication or a transureteroureterostomy.
Figure 15.13 Different types of ureteral stents.
Figure 15.14 Ideal placement of a JJ ureteral stent. Proximal loop into the pelvis and distal loop not longer than the midline of the coccyx.
Chapter 16
Figure 16.1 Complications of nephrostomy tubes – kinking.
Figure 16.2 a) Bilateral subcutaneous extra-anatomic stent b) Unilateral subcutaneous stent.
Figure 16.3 Pigtail of the Paterson-Forrester subcutaneous stent.
Figure 16.4 Semi-lateral positioning of the patient with two 3-liter bags of saline to elevate the ipsilateral side and a Lloyd-Davis cystoscopy position.
Figure 16.5 Iodine skin and nephrostomy tube preparation plus draping.
Figure 16.6 The operator sits and injects neat contrast (Urografin 150) to outline the collecting system.
Figure 16.7 A sensor wire is placed through the nephrostomy tube and a skin ellipse cut to excised the skin puncture site of the nephrostomy site. The skin edges are also undermined.
Figure 16.8 A minor open surgical tray is used to prepare for the skin excision and tunneling procedure.
Figure 16.9 A series of subcutaneous jumps are made to tunnel the stent using the Alken dilators.
Figure 16.10 The bladder puncture procedure includes a nephrostomy type needle (16 Gauge) and a short size 11 FG peel-away sheath.
Figure 16.11 Skin closure with inverting 4/0 Vicryl Rapide sutures (9971) and cyanoacrylate glue as a sealant and dressing.
Figure 16.12 a) Secure the subcutaneous stent with mosquito clips to open the fibrous track. In this case an extra-anatomic stent in a transplant is being replaced b) X-ray screening is used to control the stent.
Figure 16.13 Misplaced stent – on CT scanning the coil of left extra-anatomic stent can be seen behind the bladder. This required repositioning under cystoscopic and radiological control.
Figure 16.14 Early complications can include superficial cellulitis along the track. Treatment with IV antibiotics can resolve this in a freshly placed stent.
Figure 16.15 Skin erosion due to infection along the track occurs in patients when the stent is blocked or needs changing.
Figure 16.16 Cancer cells can seed along the subcutaneous track if the lower of the stent passes through pelvic cancer and thus active bladder involvement is contraindication for this technique.
Chapter 17
Figure 17.1 The Paterson-Forrester stent.
Figure 17.2 A peel-away sheath into the pelvicalyceal system is used to insert the proximal coil of the Paterson-Forrester stent.
Figure 17.3 A peel-away sheath is then used to tunnel the Paterson-Forrester stent to the iliac fossa and the distal coil will then be inserted into the bladder.
Figure 17.4 A functioning Paterson-Forrester stent draining the right kidney to the bladder. The patient has a left ureteric JJ stent and left Foley catheter nephrostomy in place. Both kidneys drained via the left nephrostomy.
Figure 17.5 The detour stent being passed over a guidewire into the pelvicalyceal system via 32 F Amplatz sheath. Note the section lying in the renal pelvis is 20 F soft silicone, there is then a yellow teflon section, which anchors to the renal cortex. A PTFE 28 F section protects the extra anatomic section of the stent.
Figure 17.6 The detour stent has been inserted through the Amplatz sheath into the renal pelvis but the Teflon-coated section corresponding to the metallic ring needs withdrawing 2 cm to lie within the renal cortex. This is best accomplished by reinserting the Amplatz sheath over the tube rather than pulling on the Detour stent.
Figure 17.7 After passing an Amplatz sheath over the Detour stent and withdrawing the stent 2 cm the teflon ring is lying closer to the renal cortex. One further correction was made to get the positioning optimized.
Figure 17.8 A hollow plastic dilator with a removal nose cone is used to make a subcutaneous tunnel.
Figure 17.9 After passing the track dilator subcutaneously the nose cone is removed and the Detour stent passed through the hollow tube.
Figure 17.10 The Detour stent has been passed through the tunneler. Methylene blue plus contrast injected back through the Detour stent is used to check free communication with the pelvicalyceal system.
Figure 17.11 Both Detour stents have now been brought out to the anterior abdominal wall at the site for siting the drainage bag.
Figure 17.12 The PTFE coating around the inner silicone tubing is carefully cut back to 2 cm deep to the skin making sure that the silicone tube is not inadvertently punctured.
Figure 17.13 The silicone tubes have now been exposed and shortened.
Figure 17.14 The tubing has now been covered with an ileostomy bag.
Figure 17.15 An IVU 10 minutes post injection showing unobstructed pelvicalyceal systems draining into a bag in the right iliac fossa via bilateral extra anatomic Detour stents.
Figure 17.16 This patient had bilateral Detour stents inserted 6 months previously and now has eroded the detour stent through the skin at the site of the nephrostomy puncture.
Figure 17.17 A CT scan on the same patient showing that the initial puncture had passed through the descending colon. Amazingly, the Detour stent had functioned without any problem for 6 months.
Chapter 18
Figure 18.1 Pathway between tandem ureteral stents for extraluminal urine flow, even in the presence of extrinsic compression.
Chapter 19
Figure 19.1 Uriprene
TM
degradable ureteral stent. This stent is composed of three components: an inner coil, an overlaid mesh, and an external coating. Each component is made out of commonly used dissolving suture materials, specifically Glycolide, ε-caprolactone, and trimethylene carbonate. The coating is applied in a gradient fashion with more coating toward the kidney coil and less on the distal end to ensure that it degrades from the bladder end first. Pre-clinical animal studies have shown the stent degrades in 3–4 weeks after implantation. A first-in-human safety study is currently underway.
Chapter 20
Figure 20.1 Metallic prostatic stents.
Figure 20.2 Memokath 051 stents.
Figure 20.3 Memokath stent in malignant stricture 37 F. Ca Breast. Solitary functioning kidney, total ureteric obstruction. 22 cm Memokath.
Figure 20.4 Memokath stent in benign stricgture a) latrogenic injury at PUJ Solitary kidney b) IVU 1 year after stent insertion.
Figure 20.5 Resonance Stent.
Figure 20.6 a) Allium Stent b) Allium Ureteric Stent c) Ureteric obstruction due to Ca prostate d) Allium stent in-situ for 18 months.
Figure 20.7 Uventa Ureteric Stent.
Figure 20.8 Uventa Ureteric Stent a) Left ureteric stricture Recurrent colonic carcinoma b) KUB x ray c) IVU 3 months after stent insertion.
Chapter 21
Figure 21.1 Imaging before stent removal. Heavily encrusted stent.
Figure 21.2 Stent on a string.
Figure 21.3 Stent removal forceps.
Figure 21.4 Memokath stent removal.
Figure 21.5 Uromax balloon.
Figure 21.6 Uri-glow Stent.
Chapter 23
Figure 23.1 Migrated and Fragmented JJ stent.
Figure 23.2 Migrated and Fragmented JJ stent.
Figure 23.3 Misplaced JJ stent. Ante-grade placement of JJ stent in the distal end in vagina. Ureteroscope in distal ureter during re-positioning.
Figure 23.4 Distal migration of Memokath stent a) Bilateral ureteric obstruction due to lymph nodal metastases from carcinoma of anal canal b) Distal migration of left stent 6 months after insertion.
Figure 23.5 Proximal migration of Memokath stents a) Ca rectum. Radiation fibrosis Bilateral Memokath stents b) Migrated stents Bilateral JJ stents and right nephrostomy.
Figure 23.6 Heavily calcified forgotten JJ stent which needed per-cutaneous removal.
Chapter 24
Figure 24.1 Validated patient information leaflet [24].
Figure 24.2 Ureteric stent symptom questionnaire for when stent in situ.
Figure 24.3 Ureteric stent symptom questionnaire for when stented.
Guide
Cover
Table of Contents
Begin Reading
Pages
iii
iv
vii
viii
ix
x
xi
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
Ureteric Stenting
Edited by Ravi Kulkarni
Ashford and St Peter’s Hospitals NHS Foundation Trust, UK
This edition first published in 2017© 2017 by John Wiley & Sons Ltd
Registered OfficeJohn Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK
Editorial Offices9600 Garsington Road, Oxford, OX4 2DQ, UKThe Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK.111 River Street, Hoboken, NJ 07030-5774, USA
For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com/wiley-blackwell
The right of Ravi Kulkarni to be identified as the editor of this work has been asserted in accordance with the UK Copyright, Designs and Patents Act 1988.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher.
Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought.
The contents of this work are intended to further general scientific research, understanding, and discussion only and are not intended and should not be relied upon as recommending or promoting scientific method, diagnosis, or treatment by physicians for any particular patient. In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of medicines, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each medicine, equipment, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. While the publisher and authors have used their best efforts in preparing this work, they make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives, written sales materials or promotional statements for this work. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further information does not mean that the publisher and authors endorse the information or services the organization, website, or product may provide or recommendations it may make. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.
Library of Congress Cataloging-in-Publication Data
Names: Kulkarni, Ravi, 1953– author.Title: Ureteric stenting / Ravi Kulkarni.Description: Chichester, West Sussex ; Hoboken, NJ : John Wiley & Sons Inc., 2017. | Includes bibliographical references and index.Identifiers: LCCN 2016044215 | ISBN 9781119085683 (cloth) | ISBN 9781119085690 (Adobe PDF) | ISBN 9781119085706 (epub)Subjects: | MESH: Ureter–surgery | Stents | Ureteral Obstruction–surgery | Drainage–methods | Urologic Diseases–prevention & controlClassification: LCC RD578 | NLM WJ 26 | DDC 617.4/62–dc23LC record available at https://lccn.loc.gov/2016044215
A catalogue record for this book is available from the British Library.
Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books.
Cover image courtesy of macroworld/GettyimagesCover design by Wiley
List of Contributors
Husain AleneziEndourology FellowDivision of Urology, Department of SurgerySchulich School of Medicine & Dentistry-Western UniversityLondon, OntarioCanada
Justin ChanDepartment of Urologic sciences, The Stone Centre at Vancouver General Hospital, Jack Bell Research CenterVancouver, British ColumbiaCanada
Alex ChapmanConsultant RadiologistAshford and St Peter’s Hospitals NHS Foundation TrustChertsey, SurreyUK
Ben H. ChewAssistant Professor of Urology University of British ColumbiaVancouver, British ColumbiaCanadaDirector of Clinical Research, The Stone Centre at Vancouver General Hospital, Vancouver, Canada
Robin ColeConsultant Urological SurgeonAshford and St Peter’s HospitalsNHS Foundation TrustChertsey, Surrey, UK
Jonathan CloutierConsultant Urologist, Department of UrologyUniversity Hospital Center of Quebec CitySaint-François d’Assise HospitalQuebec CityCanada
John D. DenstedtProfessor of UrologyDivision of Urology, Department of SurgerySchulich School of Medicine & Dentistry-Western UniversityLondon, OntarioCanada
Steeve DoiziResearch Fellow, Endourology and Stone Disease, Department of UrologyUniversity of Texas Southwestern Medical CenterDallas, TexasUSA
Rami EliasLaparoscopy and Endourology FellowDivision of Urology, McMaster UniversityHamilton, OntarioCanada
Helena GrestyDepartment of Academic SurgeryThe Royal Marsden NHS FoundationTrust,London, UK
Chad M. GridleyDepartment of UrologyThe Ohio State University Wexner Medical CenterOhio, USA
David I. HarrimanDepartment of Urologic Sciences University of British ColumbiaVancouver, BCCanada
Alexander P. JayClinical FellowThe Royal Marsden NHS Foundation Trust, LondonUK
Navroop JohalDepartment of Academic SurgeryThe Royal Marsden NHS Foundation Trust,London, UK
Hrishi B. JoshiConsultant Urological Surgeon and Honorary Lecturer, Department of UrologyUniversity Hospital of Wales and School of Medicine, Cardiff UniversityWalesUK
Panagiotis KallidonisUrology SpecialistDepartment of Urology University Hospital of PatrasPatrasGreece
Wissam KamalDepartment of Urology University Hospital of PatrasPatrasGreece
Bodo E. KnudsenInterim Chair, Program DirectorAssociate Professor and Henry A. Wise II Professorship in UrologyDepartment of UrologyThe Ohio State University Wexner Medical CenterUSA
Ravi KulkarniConsultant Urological SurgeonAshford and St Peter’s Hospitals NHS Foundation TrustChertsey, Surrey, UK
Pardeep KumarConsultant Urological Surgeon Department of Academic SurgeryThe Royal Marsden NHS FoundationTrust, LondonUK
Dirk LangeDirector of Basic Science Research, Assistant Professor of UrologyThe Stone Centre at Vancouver GeneralHospital, Jack Bell Research CenterVancouver, British ColumbiaCanada
David A. LeavittThe Smith Institute for UrologyHofstra-North Shore-LIJ Health SystemNew Hyde Park, NYUSA
Evangelos LiatsikosProfessor of UrologyDepartment of UrologyUniversity Hospital of PatrasPatras, Greece
Stuart Nigel LloydConsultant Urological SurgeonHinchingbrooke Park, HuntingdonUK
Edward D. MatsumotoProfessor of UrologyDivision of UrologyDepartment of SurgeryDeGroote School of MedicineMcMaster UniversityHamilton, OntarioCanada
Piruz MotamediniaThe Smith Institute for UrologyHofstra-North Shore-LIJ School of MedicineNew Hyde Park, NYUSA
David L. NicolChief of Surgery/Consultant UrologistThe Royal Marsden NHS Foundation Trust, LondonUKProfessor of Surgical OncologyInstitute of Cancer Research, UKProfessor of SurgeryUniversity of QueenslandAustralia
Zeph OkekeThe Smith Institute for UrologyHofstra-North Shore-LIJ School of MedicineNew Hyde Park, NYUSA
Vasilis PanagopoulosDepartment of Urology University Hospital of PatrasPatras, Greece
Margaret S. PearleProfessor of Urology and Internal MedicineUniversity of Texas Southwestern Medical CenterDallas, Texas,USA
Stephen PerrioAshford and St Peter’s Hospitals NHS Foundation TrustChertsey, SurreyUK
Aditya RajaResearch Fellow in Urology University Hospital of Wales and School of Medicine, Cardiff UniversityCardiff, WalesUK
Ravindra SabnisProfessor of UrologyDepartment of UrologyMuljibhai Patel Urological HospitalNadiad, GujaratIndia
Arthur D. SmithProfessor of UrologyThe Smith Institute for UrologyHofstra North Shore-LIJ School of MedicineNew Hyde Park, NYUSA
Thomas O. TaillyDivision of Urology, Department of SurgeryGhent University HospitalsGhentBelgium
Dominic A. TeichmannSpecialist Registrar in UrologyUniversity Hospital of Wales and School of MedicineCardiff University, WalesUK
Andrew M. ToddDepartment of UrologyThe Ohio State University Wexner Medical CenterOhioUSA
Olivier TraxerProfessor of UrologyDepartment of UrologyTenon University HospitalPierre & Marie Curie UniversityParis, France
Graham WatsonConsultant Urologist and Chairman, Medi Tech TrustBMI The Esperance HospitalEastbourneUK
Philip T. ZhaoThe Smith Institute for UrologyHofstra North Shore-LIJ School of MedicineNew Hyde Park, NYUSA
Foreword
The Urology World has long awaited a book entirely devoted to ureteral stents.
Dr. Kulkarni has assembled an impressive selection of contributors to this book all of whom are experts in the field. Various types of stents are described and all aspects of stenting, including techniques of insertion and the complications that may ensue, are discussed.
It is now a relatively simple matter to insert a ureteral stent either to overcome an obstruction or to prevent it. Indeed, too frequently, ureteral stents are inserted with no thought given to the problems that may arise when they are subsequently removed (see chapter 20).
For example, patients with bilateral ureteral obstruction caused by a malignancy are invariably stented without discussing with the patient and/or family the alternative of non-intervention. In many instances, a fairly rapid demise from uraemia may in fact be preferable to stenting a patient and extending a life of poor quality and severe pain.
My single message to the readers of this book is that the possible consequences of stenting should always be considered before embarking on this form of therapy.
I congratulate Dr. Kulkarni for this major contribution to the urologic literature. This book will certainly be appreciated by its readers and will be invaluable in the treatment of their patients.
Professor Arthur SmithThe Arthur Smith Institute of UrologyLong IslandNew Hyde ParkNew York
Preface
Ureteric stenting is one of the most common urological procedures. The idea of writing a book on the subject seemed like stating the obvious. But when I thought about the subject, it lent itself as a little challenge. The changes in designs, materials and the evolution of technical alternatives over the past decades alone have been so extensive that a compilation felt worthwhile.
Many enthusiasts have done sterling work on different aspects of stents. These contributions have been published and are well recognised. However, not many have reached the operating theatres of the practicing urologist nor have these advances passed on to the patients who would benefit from these modifications. Making the urological community aware of these seemed like a good idea.
Original research on the physiology of the ureter to the new biodegradable materials has enriched our knowledge and has provided a platform to consider alternatives. The quantification of stent related morbidity and the cost benefits have also been brought to our attention in the new cost-conscious world in which clinical practice is critically evaluated.
This treatise of a wide spectrum of chapters written by some of the well-recognised authorities in the world will provide a valuable source of scientific and practical information to all those involved in managing ureteric obstruction. Aimed at all levels of urologists and radiologists, this book will hopefully offer some technical as well as conceptual hints. I anticipate, it will also generate enthusiasm so necessary to keep innovation at the forefront of this field.
I am most grateful to all the authors for their efforts and the time. Special thanks to Prof Arthur Smith, whose advice from the very concept to the selection of topics has been of enormous value.
I would like to thank my wife Meena for putting up with me during this work!
Ravi Kulkarni MS FRCSConsultant Urological SurgeonAshford and St Peter’s Hospital NHS Foundation TrustChertsey, Surrey, UK
1Anatomy of the Human Ureter
Ravi Kulkarni
Consultant Urological Surgeon, Ashford and St Peter’s Hospitals NHS Foundation Trust, Chertsey, Surrey, UK
The ureter is a muscular tube, which connects the renal pelvis to the urinary bladder. Approximately 25 to 30 cm long, it has a diameter of about 3 mm. It has three natural constrictions. The first at the pelvi-ureteric junction, the second at the pelvic brim where it crosses the iliac vessels, and finally at the uretero-vesical junction (Figure 1.1). The narrowest part of the ureter is the intra-mural segment at the uretero-vesical junction [1].
Figure 1.1 Anatomy of the ureter.
The ureter traverses the retro-peritoneal space in a relatively straight line from the pelvi-ureteric junction to the urinary bladder. Lying in front of the psoas major muscle, its course can be traced along the tips of the transverse processes of the lumbar vertebrae [2].
Its posterior relations in the abdomen are the psoas major muscle and the genito-femoral nerve. The right ureter is covered anteriorly by the second part of the duodenum, right colic vessel, the terminal part of the ileum, and small bowel mesentery. The anterior relations of the left ureter are the left colic vessels, the sigmoid colon, and its mesentery. The gonadal vessels cross both the ureters anteriorly (Figure 1.2) in an oblique manner [3–6].
Figure 1.2 Blood supply of the ureter.
The ureter enters the pelvis at the bifurcation of the common iliac artery. The segment of the ureter below the pelvic brim is approximately of the same length as the abdominal part. It traverses postero-laterally, in front of the sciatic foramen and then turns antero-medially. In its initial course, it lies in front of the internal iliac artery, especially its anterior division and the internal iliac vein – an important relationship for the pelvic surgeon [6, 7]. It crosses in front of the obliterated umbilical artery, obturator nerve and finally the inferior vesical artery (Figure 1.2).
The relations with the adjacent organs from this part vary in both the sexes and are of clinical significance.
In the male, it is crossed by the vas deferens from the lateral to the medial side. The ureter then turns infero-medially into the bladder base just above the seminal vesicles.
In a female, the ureter passes behind the ovary and its plexus of veins – an important relation that makes it vulnerable to trauma during the ligation of these veins (Figure 1.2). It lies in the areolar tissue beneath the broad ligament. It is then crossed by the uterine artery, which lies above and in front of the ureter and yet again renders the ureter to injury. The subsequent part of the ureter bears a close relationship to the cervix and the vaginal fornix. It lies between 1 and 4 cm from the cervix. The course in front of the lateral vaginal fornix can be variable. The ureter may cross the midline and therefore, a variable part may lie in front of the vagina [8–10].
The intra-mural part of the ureter is oblique and is surrounded by the detrusor muscle fibres. Both these features result in the closure of the lumen and are responsible for prevention of reflux of urine during voiding. The two ureteric orifices are approximately 5 cm apart when the bladder is full. This distance is reduced when the bladder is empty.
1.1 Structure
The ureter does not have a serosal lining. It has three layers: the outermost, fibrous and areolar tissue, the middle, muscular, and innermost, the urothelial. The fibrous coat is thin and indistinct (Figure 1.3).
Figure 1.3 Histology of the ureter.
The smooth muscle fibers that provide the peristaltic activity are divided in circular and longitudinal segments. The inner, circular bundles are mainly responsible for the forward propulsion of urine. The longitudinal coat is less distinct in its proximal part. Additional longitudinal fibers are seen in the distal part of the ureter. The muscle coat of the ureter is rarely arranged in two specific layers.
The inner, urothelial lining is of transitional epithelium. It is four to five cell layers thick in the main part of the ureter but is much thinner in its proximal part where it is two to three cell layers (Figure 1.3). It has very little sub-mucosa. Mostly folded longitudinally, it merges with the urothelium of the bladder at the distal end.
1.2 Blood Supply
The ureter draws its blood supply in a segmental fashion (Figure 1.2). There is a good anastomosis between the arterial branches arising from renal artery, abdominal aorta, gonadal vessels, common iliac, internal iliac, superior and inferior vesical arteries. Ureter also has branches arising from the uterine artery in females. Despite the extensive internal anastomoses, the blood supply of the distal 2–3 cm of the ureter is unpredictable [9]. This makes this segment vulnerable to ischemia if dissected excessively.
The venous drainage of the ureter follows the arteries and ultimately leads into the inferior vena cava.
Lymphatic drainage of the ureter is also segmental. The internal, communicating plexus of lymphatics within the walls of the ureter drain into the regional lymph nodes. The lymphatics from the proximal part of the ureter drain into the para-aortic lymph nodes near the origin of the renal artery. The distal abdominal segment drains in the para-aortic as well as common iliac lymph nodes. The lymphatics from the pelvic segment of the ureter drain into the internal and subsequently into the common iliac lymph nodes [10–12].
1.3 Nerves
The autonomic nerve supply of the ureter arises from the lumbar and sacral plexuses. The proximal part of the ureter derives the nerve supply from the lower thoracic and the lumbar plexus whereas the distal and pelvic part from the sacral. Pain fibers to the ureter predominantly arise from L1 and L2 segments, which explain the referred pain to the relevant dermatome. The nerve fibers are sparse in the proximal part but plentiful in the distal segment. Ureteric peristalsis is largely independent of its innervation. A downward wave, initiated in the collecting system, much like the sino-atrial node in the heart, is believed to be responsible for the forward propulsion of urine towards the bladder. A paralysis of this intrinsic neuro-muscular activity can occur due to an obstructive or inflammatory process.
1.4 Embryology
Ureteric buds develop and grow in a cephalad fashion from the embryonic bladder. The superior ends of these buds are capped with the meta-nephros, which develops in to the adult kidney (Figures 1.4 and 1.5). The proximal extension of the ureteric bud develops into the renal pelvis, calyces and the collecting tubules. Meta-nephros, which develops from the mesoderm, forms up to 1000,000 nephrons, which join the collecting tubules to form the final functional units of the adult kidney. Once the meta-nephros and the developing collecting system have reached its lumbar destination, it gains attachment to the adrenals. Medial rotation of the embryonic kidney results in alteration of relationship of both kidneys to the neighbouring organs.
Figure 1.4 Ureter embryology, part one.
Figure 1.5 Ureter embryology, part two.
The separation and proximal growth of the ureteric buds has an important bearing on the ureteric and renal anomalies. The lack of separation of the meta-nephros will lead to the development of a horseshoe kidney (Figure 1.6). Similarly, any deviation in the normal development of the bud will lead to duplex or fused ectopia.
Figure 1.6 Horse-shoe kidney.
1.5 Congenital Variations
1.5.1 Reto-caval ureter
The right ureter may cross behind the inferior vena cava (retro-caval ureter). The incidence is reported to be 1 in 1500 patients. More common in males than in females, this congenital variation is considered an anomaly of the development of the vena cava rather than the ureter. So, the term pre-ureteral cava is more appropriate (Figure 1.7).
Figure 1.7 Retro-caval ureter.
1.5.2 Duplex
Duplication of the ureteric bud may result in a variety of anomalies. This may be in the form of two separate systems on both sides or a duplex ureter at variable levels which get fused anywhere from the PUJ to the ureteric orifice. The location of the ureteric orifices of a duplex system is governed by what is known as the Weigert-Meyer law, which states that the ureteric orifice of the upper moiety is more medial and caudal where as that of the lower segment is more cranial and lateral (Figure 1.8). The upper moiety is usually small and its ureter is more likely to suffer with obstruction or an ureterocoele. The lower moiety is more prone to reflux.
Figure 1.8 Duplex ureter.
1.5.3 PUJ Obstruction
A functional narrowing of the uretero-pelvic junction results from muscular hypoplasia or a neuro-muscular abnormality. A lack of the progression of the peristaltic wave at this location results in functional obstruction. Progressive dilatation of the renal pelvis follows and causes stasis. These two features lead to complications such a formation of calculi, infection, pain, and a progressive loss of renal parenchyma if corrective surgery is delayed.
Other variations include a high attachment of the ureter to the pelvis, a long segment of atresia and segmentation of the renal pelvis. Associated with a PUJ obstruction, the renal artery or its branches may cross the ureter, potentially leading to obstruction. The role of crossing vessels near the pelvic-ureteric junction and their influence on obstruction to the upper tract is often difficult to assess. Whether they lead to the dilatation of the renal pelvis or the latter appears obstructed due to the over-hang is often debatable.
1.5.4 Ectopic Ureteric Orifice
This rare form of anomaly is often seen with the upper moiety of a duplex system. In a fully developed single renal unit, the ureter may drain in the posterior urethra, seminal vesicle, or the vas deferens. In a female, the orifice may be in the urethra, vagina, or the perineum, and presents with incontinence.
1.5.5 Ureterocoeles
Usually seen in the upper moiety of a duplex system or an ectopic ureter, these are due to the failure of canalization of the ureteric bud.
1.5.6 Mega-Ureter
A grossly dilated ureter with a narrow uretero-vesical junction is the typical appearance of this condition. An a-peristaltic segment of the distal segment is the possible cause. There may be an associated reflux. This anomaly may be seen with other abnormalities such as prune belly and other syndromes.
1.5.7 Ureteric Diverticulae
This rare anomaly is due to the variation in the development of the ureteric bud.
1.6 Clinical Significance
The importance of anatomy of any organ cannot be over-emphasised to a surgeon.
Awareness of the normal anatomy and its variations can help the surgeon to avoid trauma during procedures that involve dissection of the ureter. Accidental tears, trans-section, ligation, heat damage caused by diathermy, ligasure, harmonic scalpel, or laser energy can be reduced by careful separation of the ureter. Such heat damage can be subtle and manifest much later when tissue necrosis develops following ischemia. The knowledge of the blood supply is important. Avoiding excessive mobilization can prevent the development of ischemic strictures following ureteric surgery. Although distensible, the diameter of the ureter should be respected. Insertion of wide-bore instruments invariably leads to tears and subsequent scarring. Increasing use of ureteroscopy and the use of devices such as lasers has led to a rise of iatrogenic ureteric trauma.
References
[1]
Davies DV, Coupland RE.
Grey’s anatomy
,
34th ed
. Orient Longman, Harrow, Essex, UK, 1989, 1538–1540.
[2]
McMinn RMH.
Last’s Anatomy, Regional and Applied
,
9th ed
. Churchill Livingstone, Elsevier, UK, 2013, 371.
[3]
Schenkman NS. Standard anatomy and variants. In: Ureter Anatomy, (Gest TR, ed). Medscape, New York, US. 2013.
[4]
Knipe H, Butler, I. Ureter. Available at:
https://Radiopaedica.org/articles/ureter
(accessed October 19, 2016).
[5]
Butler P, Mitchell A, Healy JC.
Applied radiological anatomy
,
2nd ed
. Cambridge University Press, 2012, 110–113.
[6]
Ryan S, McNicholas M, Eustace S.
Anatomy for diagnostic imaging, 2e
. Saunders Ltd., 2004.
[7]
Pal M. Urogynecology & pelvic reconstructive surgery. April 2016. Available at:
http://www.teachMeanAtomy.info
(accessed October 19, 2016).
[8]
Schlossberg L, Zuidema GD. 1997. The John Hopkins Atlas of Human Functional Anatomy. Available at:
http://www.radiopaedia.org/articles/ureter
(accessed October 19, 2016).
[9]
Uninary Systems. Ureter. Chapter 33. 2016. Available at:
http://www.www.mananatomy.com/body-systems/urinary-system/ureter
(accessed October 19, 2016).
[10]
My KenHub. The Ureter. n.d. Available at:
http://www.kenhub.com/en/library/anatomy/the-ureters
(accessed October 19, 2016).
[11]
Anatomy of the Ureter. 2015. Available at:
http://www.emedicine.medscape.com/article/378075-overview
(accessed October 19, 2016).
[12]
Anatomy of the Ureter. December 2015. Available at:
http://www.anatomyatlases.org/AnatomicVariants
(accessed October 19, 2016).
2Anatomic Variations of the Ureter
Piruz Motamedinia1, David A. Leavitt2, Philip T. Zhao1, Zeph Okeke1 and Arthur D. Smith3
1The Smith Institute for Urology, Hofstra North Shore-LIJ School of Medicine, New Hyde Park, NY, USA
2The Smith Institute for Urology, Hofstra-North Shore-LIJ Health System, New Hyde Park, NY, USA
3Professor of Urology, The Smith Institute for Urology, Hofstra North Shore-LIJ School of Medicine, New Hyde Park, NY, USA
A normal ureter is a narrow, tubular structure that carries urine between the renal pelvis and the bladder. Far from a passive tube, the ureter has three distinct muscular layers surrounding a specialized urothelium, which actively propels urine to the bladder. The ureter narrows at distinct points along its course including the ureteropelvic junction (UPJ), the ureteral segment over the iliac vessels/pelvic brim, and the ureterovesical junction (UVJ). These act as common points of obstruction for a passing stone. However, variations in normal anatomy result in a higher likelihood or even increased degree of obstruction, and present several challenges to stent placement.
2.1 Horseshoe Kidney
Horseshoe kidney (HSK) is the fusion of the right and left kidneys at their lower pole across the midline. The point of fusion is referred to as the isthmus and varies in quality from a thin, fibrous band to thicker, functional renal parenchyma. HSK occurs in about 1 in 400 to 666 individuals and is twice as common in men [1, 2]. The higher incidence of HSK seen in children can be explained by the co-occurring non-urologic comorbidities limiting their overall survival. Associated urologic abnormalities include UPJ obstruction (17%), vesicoureteral reflux (20–50%), and ureteral duplication (10%).
Normally, kidneys ascend to the upper retroperitoneum, just below the liver or spleen. They rest on the psoas muscles resulting in a line with the upper pole slightly more medial to the lower pole. With HSK, the isthmus is tethered by the inferior mesenteric artery limiting kidney ascent resulting in the lateral rotation of the upper poles with an anterior displacement of the renal pelvises [3].
The ureter has a high insertion into the renal pelvis in HSK with an increased incidence of ureteropelvic junction (UPJ) obstruction of about 13–35% [2]. Moreover, the ureter courses over the isthmus creating another point of obstruction and urinary stasis, raising the risk of nephrolithiasis and urinary tract infection (UTI) [4–6].
Management of stones offers several challenges in patients with HSK given their abnormal renal and ureteral anatomy. Shock wave lithotripsy (SWL) is an option; however, the reliance on passive clearance results in poor stone free rates (31–70%) [7, 8]. Ureteroscopy is plausible and one series was able to demonstrate excellent stone-free rates in patients with stones ≰10 mm [9]. Larger stones up to 16 mm were more likely to have residual fragments or require multiple procedures.
PCNL offers the best outcomes regarding stone-free rates (75–100%) [7, 8, 10]; however, major complications including bleeding, sepsis and bowel injury are more common, albeit still rare. Given the lower position and abnormal rotation of HSK pre-operative cross-sectional imaging is paramount to accurately assess stone burden and also proximity of major blood vessels and organs including bowel and pleura. The anterio-medial rotation of the lower pole results in the upper poles being the most posterior region of the HSK and so the preferred point of access. Patients with HSK have a higher incidence of retrorenal colon (3–19%) and as such are at an increased risk of bowel perforation during percutaneous access [11, 12].
In other cases of renal ectopia with or without fusion are far less common than HSK [13]. Ureteral anomalies similar to HSK continue to occur and their course is dependent on the kidneys final position relative to the intended ipsilateral trigone.
2.2 Duplex Ureter
The incidence of upper tract duplication is 0.5 to 0.7% of the asymptomatic population and 1% to 10% of children with UTIs [14]. The most common variation is a partial duplication (70%) with a common ureter entering the bladder [15]. Complete duplications are more likely to have additional comorbidities including reflux, ureteral obstruction, or ureterocele. Ureteral duplication is difficult to appreciate on a non-contrast CT scan and contrast enhancement is suggested when suspicion is high [16]. The Weigert-Meyer rule dictates that in a completely duplicated system, the lower-pole moiety implants more laterally in the bladder with a shorter intramural segment more prone to reflux [17]. Conversely, the upper-pole moiety implants caudally and is more likely to be ectopic and obstructed.
Stent placement in a partially duplicated ureter can be challenging. If electing to only stent a single system, the surgeon should chose a stent with side holes throughout its entire length. If retrograde wire placement does not preferentially cannulate the desired moiety, an angled-tip catheter can direct a glidewire at the point of bifurcation. Alternatively, ureteroscopy with direct visualization of the desired ureter at its bifurcation may be required. If a retrograde approach is unsuccessful, percutaneous antegrade ureteral stent is preferred. Surgeons should consider stenting both moieties to prevent de novo compression and obstruction of the unstented moiety.
2.3 Megaureter
A normal ureteral diameter is between 3–5 mm. Dilation greater than 7 mm may be considered a megaureter [18]. Etiologies include primary or secondary (due to bladder outlet obstruction) reflux, or ureteral obstruction attributable to segmental narrowing or aperistalsis. Megaureters have been described as obstructing and refluxing; however, this combination is less common [19]. Aperistaltic dilation without obstruction is thought to be secondary to abnormal muscle fibers or collagen deposition [20].
Congenital megaureter is primarily a pediatric diagnosis, often diagnosed in utero given the near ubiquitous use of neonatal sonographic screening. For children who escape discovery or remain asymptomatic, about half spontaneously resolve without the need for intervention [21, 22]. Congenital megaureter diagnosis in adults is rare and proceeded by symptoms secondary to obstruction or infection. Ureteral stones, which developed due to urine stagnation in the dilated segment have been described in 36% of patients with symptomatic megaureter [23].
