Urinary reconstruction in kidney transplantation

1. Particularities of the transplanted ureter

Urinary reconstruction is a fundamental step of kidney transplantation. Even when the graft's vascular perfusion is adequate, a ureteral complication can seriously compromise its function.

Unlike the native ureter, which receives segmental blood supply from multiple sources, the graft ureter depends fundamentally on the proximal vascularization preserved during organ procurement.

The ureteral blood supply of the graft comes mainly from branches related to the renal artery and the proximal periureteral vascular system, which run through the periureteral tissue. Therefore, excessive dissection of the ureter during retrieval, bench surgery, or implantation can lead to distal ischemia.

2. Preservation of periureteral tissue

During procurement and graft preparation, the adipose and connective tissue accompanying the ureter must be preserved, especially in its relationship with the renal pelvis and the lower pole. Extensive skeletonization of the ureter must not be performed.

The goals are:

• Preserve the periureteral vascularization.
• Avoid thermal or traumatic injury.
• Maintain sufficient length for the reconstruction.
• Prevent necrosis of the distal end.

Preserving length must not come at the expense of keeping ischemic tissue.

3. Relationship between ureteral length and complications

An excessively long ureter can favor:

• Kinking.
• Torsion.
• Redundancy.
• Impaired drainage.
• Greater vulnerability of the distal segment to ischemia.

An excessively short ureter can create tension on the anastomosis. The goal is to use the minimum necessary length that allows reaching the recipient urinary tract without tension.

4. Conditions for a safe reconstruction

Every reconstruction must meet five principles:

Principle	What it involves
1. Vascularization	Viable ends and preserved periureteral tissue.
2. Tension-free	The anastomosis must not depend on traction.
3. Adequate course	Avoid torsion, kinking, and redundancy.
4. Watertight closure	Correct tissue apposition and careful suturing.
5. Drainage	Avoid obstruction and maintain decompression when appropriate.

5. Urinary tract reconstruction techniques

The most commonly used technique in kidney transplantation is ureteroneocystostomy, which connects the graft ureter to the recipient's bladder. The main alternatives are:

• Lich-Gregoir extravesical ureteroneocystostomy.
• Politano-Leadbetter transvesical ureteroneocystostomy.
• Ureteroureterostomy with the native ureter.
• Pyeloureterostomy.
• Other individualized reconstructions in complex situations.

6. Lich-Gregoir extravesical ureteroneocystostomy

It is a widely used technique because of its extravesical approach and the possibility of creating an antireflux mechanism through a muscular tunnel.

Bladder preparation

Once the vascular anastomosis is complete and graft reperfusion has been verified, an area of the bladder is identified that allows the reconstruction to be performed without tension. The bladder may be partially filled with saline through the Foley catheter to facilitate its identification and handling. An area of the bladder wall close to the graft ureter is selected.

It is important to consider the final position of the kidney, making sure the ureteral course is not compromised by the arrangement of the vascular pedicle or by neighboring structures.

Ureteral preparation

The viability of the distal end is assessed. Any clearly devitalized segment is resected and the length is adjusted to avoid redundancy. Spatulating the ureteral end widens the diameter of the future anastomosis and lowers the risk of stricture.

Bladder incision

A longitudinal incision is made in the detrusor until the bladder mucosa is exposed, taking care to keep it intact at first. The length of the muscular incision will depend on the technique and the anatomy. The mucosa is then opened to a size appropriate for the anastomosis.

Ureterovesical anastomosis

The ureter is brought up to the bladder mucosa and a mucosa-to-ureter anastomosis is performed with fine absorbable suture. Either continuous or interrupted stitches may be used, depending on team preference and tissue characteristics. It is essential to avoid excessive inversion of the edges, tension, and narrowing of the anastomosis.

Double-J stent

If a ureteral stent is to be used, it can be placed during the reconstruction, verifying the position of both ends.

Muscular closure

The detrusor is approximated over the ureter, forming the extravesical tunnel. This closure must not compress the ureter excessively: a muscular reconstruction that is too tight can cause functional or mechanical obstruction.

Final check

• Verify that there is no tension.
• Make sure the ureter is not kinked.
• Check the position of the double-J stent if one was placed.
• Assess the watertightness of the reconstruction.
• Confirm adequate bladder drainage.

7. Politano-Leadbetter transvesical ureteroneocystostomy

This is a transvesical reconstruction that creates a submucosal tract for the ureter.

Technical concept

The bladder is opened and a submucosal tunnel is constructed through which the ureter is passed. The goal is to create an antireflux mechanism by means of the intramural tract.

Main steps

1. Opening the bladder.
2. Identifying the chosen implantation site.
3. Creating the submucosal tunnel.
4. Passing the ureter through the tunnel.
5. Adjusting the length and spatulating the ureter.
6. Anastomosing the ureter to the bladder mucosa.
7. Placing a double-J stent if appropriate.
8. Closing the bladder.

Advantages and limitations

It provides an antireflux mechanism, but requires a wider bladder opening and more manipulation of the bladder. Today, in many transplant programs, the extravesical technique is preferred for its simplicity and less bladder dissection. The choice should be individualized.

8. Comparison of techniques

Characteristic	Lich-Gregoir	Politano-Leadbetter
Approach	Extravesical	Transvesical
Wide bladder opening	Usually not	Yes
Antireflux mechanism	Muscular tunnel	Submucosal tunnel
Bladder manipulation	Less	More
Current use	Very common	More selective
Main consideration	Avoid compression of the tunnel	Avoid tension and angulation of the tract

9. Ureteroureterostomy with the native ureter

This consists of an anastomosis between the graft ureter and the recipient's native ureter. It can be used as a primary reconstruction or as a rescue alternative.

Indications

• Short graft ureter.
• Bladder that is difficult to access.
• Anatomical bladder abnormalities.
• Injury to or resection of the distal transplanted ureter.
• Secondary reconstruction for complications.

General technique

The ipsilateral native ureter is identified and its viability and patency are assessed. A suitable segment is selected, preserving its blood supply. An end-to-end or end-to-side anastomosis may be performed depending on the anatomy and the reconstructive plan. The ends are spatulated when appropriate and a careful suture is placed, avoiding tension or twisting. A double-J stent is usually considered to facilitate drainage during healing.

Advantages

It makes use of the native urinary tract and avoids a ureteroneocystostomy under tension.

Limitations

It requires a native ureter that is viable, patent, and functionally adequate. It should not be assumed that every recipient has a usable native ureter.

10. Pyeloureterostomy

This consists of an anastomosis between the renal pelvis of the graft and the recipient's native ureter. It is especially useful when the transplanted ureter cannot be used safely.

Possible situations

• Very short graft ureter.
• Extensive ureteral necrosis.
• Ureteral injury during procurement.
• Complex secondary reconstruction.

It requires assessing the accessibility of the renal pelvis and whether a tension-free anastomosis is possible.

11. When should a double-J stent be used?

The double-J stent promotes drainage during healing and can reduce early ureteral complications, especially leaks and obstructions. Routine use is common in many transplant programs.

It is particularly useful when there is:

• A technically complex anastomosis.
• A small-caliber ureter.
• Significant edema.
• Secondary reconstruction.
• Higher risk of early obstruction.

However, it can also promote urinary tract infection, bacterial colonization, hematuria, and encrustation if left in place too long. In uncomplicated transplants, many protocols use early removal, often between two and four weeks, individualized to the case.

12. What to do if the graft ureter is short?

The first step is to review the final position of the graft and check whether the bladder can be brought closer without compromising the vascular pedicle. If the bladder cannot be reached safely, alternatives should be considered:

1. Direct ureteroneocystostomy if there is sufficient length.
2. Selective bladder mobilization.
3. Ureteroureterostomy with the native ureter.
4. Pyeloureterostomy if the graft ureter cannot be used.
5. Other individualized reconstructions.

The choice depends on the length, vascularization, and position of the graft and on the characteristics of the bladder.

13. When should the native ureter be used?

It can be used in the setting of:

• Short graft ureter.
• Ureteral injury during procurement.
• Distal ischemia or necrosis.
• A small or complex bladder.
• Ureteral stricture or urinary leak requiring secondary reconstruction.

Before selecting it, its patency, vascularization, length, and relationship to the distal urinary tract must be assessed. Ureteroureterostomy is appropriate when a viable segment of the transplanted ureter allows the anastomosis. Pyeloureterostomy may be an alternative when there is no sufficiently viable graft ureter.

14. What to do when ureteral vascularization is doubtful?

Vascular compromise should be suspected when the ureter shows:

• Abnormal coloration.
• Extensive loss of adventitia.
• Excessive dissection.
• Friable or devitalized tissue.
• No bleeding from the cut edge, interpreted together with other findings.

Management

1. Assess overall perfusion of the graft.
2. Identify the viable ureteral segment.
3. Resect clearly devitalized tissue.
4. Reassess the available length.
5. Select a tension-free reconstruction.
6. Consider the native ureter if the remaining segment is insufficient.

Indocyanine green fluorescence can provide complementary information in experienced centers, but there is no validated universal threshold for ureteral perfusion.

15. Small-capacity bladder

Patients with advanced kidney disease and prolonged anuria may have low-capacity bladders. This does not automatically mean they require a complex reconstruction, but it does make it necessary to assess capacity, compliance, and storage pressure.

A small but low-pressure bladder can behave differently from a poorly compliant, high-pressure bladder. In selected patients, urodynamic studies and treatment of bladder dysfunction may be required before transplantation.

16. Neurogenic bladder

In these patients, urinary reconstruction must be part of a functional plan. It is important to assess:

• Bladder capacity.
• Compliance.
• Storage pressures.
• Emptying.
• Postvoid residual.
• Vesicoureteral reflux.
• Need for intermittent catheterization.

The priority is to protect the graft from a high-pressure reservoir or inadequate emptying.

17. Patients with previous bladder surgery

Previous pelvic surgery, bladder reconstructions, or urinary diversions can significantly change the strategy. The technique should be planned with appropriate anatomical and functional studies, ideally before transplantation.

18. Kidneys with a duplicated ureter

When the graft has a duplicated ureter, the options include implanting both ureters separately or performing a joint reconstruction, depending on the anatomy and vascularization. There is no universal solution. The decision should minimize dissection and avoid compromising the blood supply of both segments.

19. Urinary leak

It can result from:

• Anastomotic failure.
• Ureteral ischemia or necrosis.
• Distal obstruction.
• Increased intravesical pressure.
• Inadvertent injury to the urinary tract.

Manifestations

• Increased drain output.
• Perigraft collection.
• Pain or distension.
• Decreased urine output.
• Deterioration of renal function.

Diagnosis

Ultrasound can identify fluid collections, although it does not always establish their nature. Measuring creatinine in the drain fluid and comparing it with serum creatinine helps identify a urinary leak. Additional studies may be needed to localize it.

Treatment

It depends on the magnitude, location, ureteral viability, infection, and condition of the graft. It may include:

• Bladder drainage.
• Ureteral stent.
• Percutaneous nephrostomy.
• Drainage of collections.
• Surgical reconstruction.

Extensive ureteral necrosis or a persistent leak through nonviable tissue usually requires surgical repair.

20. Ureteral stricture

It can arise from:

• Ischemia.
• Scar fibrosis.
• Extrinsic compression.
• Kinking.
• Technical problems with the anastomosis.

Presentation

Because the graft is denervated, obstruction may present mainly as deterioration of renal function, without typical colicky pain.

Diagnosis

• Graft ultrasound.
• Assessment of renal function.
• Contrast or functional studies as needed.
• Antegrade pyelography in patients with a nephrostomy.

Treatment

The options include dilation, endourological procedures, or surgical reconstruction. The choice depends on the length, location, etiology, and recurrence of the stricture.

21. Postoperative management of the reconstruction

During the postoperative period, the following should be monitored:

• Urine output.
• Serum creatinine.
• Characteristics and volume of the drains.
• Patency of the urinary catheter.
• Hematuria and clots.
• Perigraft collections.
• Dilation of the urinary tract.
• Signs of infection.

The duration of the urinary catheter, the drain, and the double-J stent should be individualized according to the technique, the recipient's condition, and the clinical course. Devices should not be removed automatically when there are doubts about the watertightness of the anastomosis.

1. Assess the graft ureter

Viability · length · course · tension.

2. Does it reach the bladder with good perfusion and without tension?

• Yes → ureteroneocystostomy. Consider a double-J stent and verify drainage.
• No → correct the tissue and position, and reassess length and perfusion.

3. If it is still not possible: alternative reconstruction

Native ureter or another option depending on the anatomy.