Lecture Notes on Ureteric Strictures and Retroperitoneal Fibrosis

Urology Lecture Series (23/02/2026)

Instructor and Supervisors
  • Dr. Abdalla Hamza, Mmed Year 3 Urology
  • Supervisors: Dr. Waihenya, Consultant; Dr. Ikol, Consultant

Lecture Focus: Ureteric Strictures and Retroperitoneal Fibrosis

Objectives

  • Discuss the anatomy of the ureter
  • Discuss causes and pathophysiology of upper tract stricture formation
  • Review endoscopic and surgical methods for stricture management, along with their benefits and drawbacks
  • Present adjunctive technologies and materials designed to aid in ureteral reconstructive and other surgeries

Anatomy of the Ureter

  • Structure: Bilateral muscular retroperitoneal tubes as extensions of the renal pelvis.
  • Dimensions:
      - Length:
        - Adults: 22-30 cm
        - Neonates: 6.5-7.0 cm
      - Diameter: 1.5 - 6.0 mm; Lumen: 1.8 - 3.0 mm
  • Anatomical Path:
      - Lateral to the tips of the transverse processes of the lumbar vertebrae.
      - Lateralization: LEFT slightly longer than right.
  • Physiological Narrowing: Occurs at UPJ (Ureteropelvic Junction), crossing over the iliac vessels, and VUJ (Vesicoureteral Junction).
  • Key Functions:
      - Peristalsis, compliance, and non-absorbing properties.

Vascular Supply

  • Arterial Supply:
      - Proximal: branches of renal and gonadal artery and aorta.
      - Mid-ureter: Gonadal, aortic and CIA (Common Iliac Artery) branches.
      - Distal: IIA (Internal Iliac Artery), superior vesical, and inferior in males; uterine and vaginal arteries.
  • Adventitial Arterial Network:
      - Consists of smaller vessels and capillaries that penetrate to the lamina propria.
      - Abdomen = medial supply; Pelvis = lateral supply.

Histology of the Ureter

  • Layers:
      - Mucosa: Urothelium, Lamina Propria
      - Muscularis:
        - Inner longitudinal layer
        - Middle circular layer
        - Outer longitudinal layer
      - Adventitia: outer layer containing the vascular plexus.
  • Proximal Ureter: 2 muscularis layers, thinner urothelium, more compliant, prone to injury.
  • Distal Ureter: 3 muscularis layers, thicker urothelium, more resilient to injury.
  • Stricture Formation: Muscle layer disruption is a major cause (dilation, injury).

Pathophysiology of Ureteric Strictures

Wound Healing Cascade Leading to Stricture Formation

  • Phases:
      - Hemostasis Phase:
        - Platelet activation, clot formation (fibrin).
      - Early Inflammatory Phase:
        - Neutrophil recruitment.
      - Late Inflammatory Phase:
        - Macrophage involvement.
      - Proliferative Phase:
        - Fibroblast presence, collagen III deposition.
      - Remodeling Phase:
        - Collagen maturation and cross-linking, which leads to luminal narrowing and stricture formation.
  • Factors Contributing to Ureteric Fibrosis:
      - Excessive extracellular matrix deposition due to injury or chronic inflammation.
      - Damage-associated molecular patterns (DAMPs), which trigger immune responses.

Key Cytokine Involved

  • Transforming Growth Factor β (TGF-β):
      - Produced by macrophages and fibroblasts.
      - Promotes recruitment of inflammatory cells and collagen synthesis.
  • Isoforms: TGFβ1, TGFβ2, TGFβ3; mediate pro-fibrotic signaling pathways.
  • Difficulty in direct therapeutic modulation due to its diverse roles.

Etiology of Ureteric Strictures

Causes

  • Ischemic:
      - Radiation, Surgery.
  • Non-Ischemic:
      - Impacted stones, idiopathic causes, primary ureterovesical junction obstruction.
  • Extrinsic Factors:
      - Iatrogenic ligation, retroperitoneal malignancy, aneurysm.
  • Intrinsic Factors:
      - Bilharziasis, endometriosis, fibrosis, submucosal stone.
  • Intraluminal Factors:
      - Fungus ball, sloughed papilla, stones, transitional cell carcinoma.
  • Inflammatory Factors:
      - Tuberculosis, retroperitoneal fibrosis, schistosomiasis.

Acquired Ureteral Strictures and Their Causes

  • Impacted Calculi (~65%): Causes localized ischemia and inflammation leading to microdamage.
      - Impaction for >2 months has a 24% chance of stricture formation (Roberts et al., 1998).
  • Retroperitoneal Fibrosis (~15%): Involves extrinsic inflammation and compression, often idiopathic (Ormond's syndrome) thought to be part of IgG4 syndrome.
  • Endometriosis (~1%): Chronic inflammation leads to distortion and compression of the ureter.

Iatrogenic and Surgical Causes:

  • Medical and Surgical Interventions: Significant contributors to ureteral injury.
  • Gynecologic Surgery (45-74%): Most common source, particularly during hysterectomy (0.02-0.40% incidence).
  • General/Colorectal Surgery (4-17%): 0.3-10% of distal colectomies result in distal ureteric injury.
  • Surgical Risks: Recent studies indicate minimally invasive surgeries have lower injury risks than open surgeries.

Ureteroscopic Causes:

  • Ureteral Access Sheath Use: Up to 46.5% reported injury risk (Traxer & Thomas, 2013).
  • Open Surgical Anastomotic Sites: Higher incidence of strictures at sites like ureteroenteric junctions.

Radiation Therapy Effects:

  • Leads to DNA damage and microvascular injury, resulting in delayed stricture disease (e.g., cervical, endometrial cancers).
  • Cervical cancer has a risk of ≤ 0.15% annually, increasing to 2.5% after 20 years (McIntyre et al., 1995).

Evaluation of Ureteral Strictures

Diagnostic Methodologies

  • Initial Investigation: Ultrasound.
  • CT Abdomen/Pelvis with Contrast: Delayed imaging to visualize lesions (e.g., goblet sign).
  • Retrograde or Antegrade Pyelography: To confirm obstructions.
  • Diagnostic Ureteroscopy +/- Biopsy: Allows direct visualization and potential intervention.
  • Nuclear Medicine Renogram: Assess renal function and drainage.

Indications for Intervention

  • Malignancy assessment
  • Obstruction identification
  • Renal failure assessment
  • Recurrent infections
  • Persistent pain symptoms

Surgical Techniques for Ureteral Reconstruction

General Principles and Strategies
  • Surgical Goals:
      - Preservation of renal function, restoration of anatomical continuity.
  • Key Considerations:
      - Patient's general condition, timing of detection, site and extent of the defect.

Specific Surgical Techniques

  • Ureteral Stent Placement: Effective in treating intrinsic strictures with the potential for chronic management in poor surgical candidates.
      - Pros: Initial management option, facilitating drainage.
      - Cons: Chronic stenting requires frequent exchanges and is less effective for external compressions.

Endourologic Techniques for Managing Strictures

Balloon Dilation
  • Begins with a retrograde pyelogram; guidewire passed across the stricture, followed by high-pressure balloon inflation.
  • Success rates range from 50% to 76%. Best outcomes in non-anastomotic strictures.
Endoureterotomy
  • Full-thickness incision through the stricture, which can be performed using various energy sources (laser, electrocautery).
  • Particularly effective for shorter non-ischemic strictures.

Ureteral Reconstruction Strategies

Surgical Reconstruction Options

  • Techniques include ureteroureterostomy, Boari flap, or ileal interposition, depending on the location and extent of the stricture.
Autologous Ureteral Substitution Techniques
  • Ileal Ureteral Substitution:
      - Utilizes a segment of ileum, with careful consideration of bowel health and vascular integrity.
      - Commonly used in cases where ureteral length is inadequate for standard repair.
Buccal Mucosal Graft (BMG)
  • Indications:
      - For proximal/mid ureteral strictures.
  • Technique: Release ureter, excise disease, apply graft, and secure with omental wrap for vascularization.
Appendiceal Interposition
  • Utilizes appendix segment; preferred as an onlay due to lower risk compared to interposition.

Research and Future Directions in Ureteric Stricture Management

  • Advances in biomaterials for ureter management are ongoing and focus on regenerative medicine applications in reconstructive urology.

Conclusion

  • Early recognition and intervention are key in managing ureteral injuries to mitigate long-term complications including renal failure and hydronephrosis.