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Urologic complication rates after kidney transplantation using donor kidneys with duplicated or multiple ureters: a systematic review and meta-analysis of case series

This systematic review and meta-analysis of 226 recipients found that kidney allografts with duplicated or multiple ureters have low urological complication rates comparable to standard single-ureter grafts, suggesting that routine discard of these anatomically variant kidneys is not supported by current evidence.

Original authors: Azza Fithra Alhanifa, Azza Mi’raj Alfadhila, I Putu Krisna Agastya Artawan, Pande Wisnu Tirtayasa

Published 2026-07-02

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CC BY 4.0

Original authors: Azza Fithra Alhanifa, Azza Mi’raj Alfadhila, I Putu Krisna Agastya Artawan, Pande Wisnu Tirtayasa

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine you are a chef running a busy restaurant (a hospital) that needs fresh ingredients (kidneys) to save lives. Sometimes, the delivery truck brings a special, slightly unusual ingredient: a kidney that comes with two plumbing pipes (ureters) instead of the usual one. This is called "ureteral duplication."

Because this plumbing looks weird, many chefs (transplant surgeons) are scared to use it. They worry the pipes might leak, get clogged, or break because they are harder to connect to the sink (the bladder). So, they often throw these kidneys away, even though they might be perfectly healthy.

This paper is like a group of food critics (researchers) who decided to taste-test these "double-pipe" kidneys to see if they are actually safe to serve. They gathered data from 11 different kitchens around the world, looking at 226 patients who received these special kidneys.

Here is what they found, explained simply:

1. The "Leak" Test

The biggest fear was that the extra pipes would leak urine into the body.

The Finding: Only about 3 out of every 100 patients had a leak.
The Analogy: This is actually a very low leak rate. It's about the same as using a standard, single-pipe kidney. The "weird" plumbing didn't cause more spills than the "normal" plumbing.

2. The "Clog" Test

The other fear was that the pipes would get narrow or blocked (stricture).

The Finding: This was even rarer, happening in less than 1 out of every 100 patients.
The Analogy: The pipes stayed open just fine. The extra pipe didn't seem to get clogged more often than a single pipe.

3. The "Fix-It" Test

Sometimes, after the surgery, the plumbing needs a second visit from a plumber to fix a small issue.

The Finding: About 3 out of every 100 patients needed a minor surgery to fix the plumbing later.
The Analogy: This is a standard rate for any plumbing job, whether it's a simple single pipe or a complex double pipe.

4. Why Do Some Kitchens Do Better Than Others?

The researchers looked at what made the "double-pipe" kidneys work better or worse. They found three main "secret ingredients" for success:

Newer Recipes: Kitchens using more modern techniques (published in recent years) had fewer problems.
Younger Customers: Patients who were younger tended to have fewer complications.
Fresh Ingredients: Kidneys from living donors (who are carefully screened) worked better than those from deceased donors.

5. The Big Conclusion

The researchers concluded that throwing away a kidney just because it has two pipes is a waste.

Think of it like this: If you have a car with two spare tires instead of one, you don't scrap the car. You just need a mechanic who knows how to install the extra tire correctly. Similarly, kidneys with duplicated ureters are safe to use, provided the surgeon knows the right way to connect them.

The Catch:
The researchers admitted that their "taste test" wasn't perfect. The studies they looked at were old, some had missing details, and the total number of patients was small. So, while the evidence suggests these kidneys are safe, they can't say it with 100% certainty yet. They need more data to be absolutely sure.

In short: Don't throw away the kidney just because it has two pipes. With the right surgical technique, it works just as well as a kidney with one pipe.

Technical Summary: Urologic Complication Rates in Kidney Transplantation with Duplicated or Multiple Ureters

Problem Statement
The scarcity of donor kidneys has led to the frequent rejection of anatomically variant grafts, particularly those with duplicated or multiple ureters, due to concerns regarding ischemic vulnerability and subsequent urological complications. While these anomalies present technical challenges—such as the need for tailored reconstruction (e.g., separate ureteroneocystostomies or common ostium formation) and the risk of compromising the delicate periureteral vascular arcade—existing literature consists primarily of scattered retrospective studies and case reports. This lack of systematic evidence forces transplant centers to rely on anecdotal experience, potentially leading to the unnecessary discard of viable organs. There is a critical need to quantify the actual risk of urological complications in these grafts to inform acceptance criteria and operative planning.

Methodology
This study is a systematic review and meta-analysis conducted according to the PRISMA 2020 statement and registered with PROSPERO.

Data Sources: A comprehensive search was performed across Scopus, PubMed, Europe PMC, Epistemonikos, and Web of Science up to June 2026.
Inclusion Criteria: The analysis included primary, peer-reviewed case series or cohort studies involving at least five patients who received kidney transplants with duplicated or multiple ureters. Studies were required to report specific urological outcomes: total structural complications, urinary leak/fistula/urinoma, ureteral stricture/obstruction, urological surgical revision, and delayed graft function (DGF).
Data Synthesis: Pooled prevalence rates were estimated using a generalized linear mixed model (GLMM) with binomial likelihood and a logit link, a method chosen to handle rare events without zero-cell continuity correction.
Heterogeneity and Moderators: Between-study variability was assessed using the $I^2$ statistic. Meta-regression was performed to evaluate the impact of four moderators: year of publication, recipient age, ureteral stent utilization rate, and the proportion of living-donor grafts.
Quality Assessment: Methodological quality was appraised using the Joanna Briggs Institute (JBI) critical appraisal checklist for case series, and the certainty of evidence was evaluated using the GRADE methodology.

Key Results
Eleven retrospective studies comprising 226 transplant recipients were included in the quantitative synthesis.

Overall Complications: The pooled prevalence of overall structural urological complications was 5.35% (95% CI 2.02–13.4%), with no statistical heterogeneity ( $I^2 = 0\%$ ).
Specific Complications:
- Urinary leak, fistula, or urinoma: 3.42% (95% CI 0.87–12.46%).
- Ureteral stricture or obstruction: 0.88% (95% CI 0.06–11.32%).
- Urological surgical revision: 3.33% (95% CI 1.22–8.8%).
- Delayed graft function (DGF): 9.38% (95% CI 2.73–27.61%), based on only three studies.
Moderator Analysis:
- Overall complications were significantly associated with a more recent publication year, younger recipient age, and a higher proportion of living-donor grafts (all $p < 0.05$ ).
- Urinary leak was significantly associated with a higher proportion of living-donor grafts.
- Ureteral stricture was significantly associated with a more recent publication year.
- Stent utilization rate did not show a statistically significant association with any of the primary outcomes in the meta-regression.
Evidence Certainty: The certainty of evidence for all outcomes was rated as very low due to the retrospective nature of the studies, risk of bias (non-consecutive enrollment, incomplete follow-up), and imprecision resulting from the small sample size and wide confidence intervals.

Significance and Claims
The authors conclude that kidney allografts with duplicated or multiple ureters exhibit urological complication rates broadly comparable to those reported for standard single-ureter grafts (which typically range from 2% to 15%). Consequently, the study argues that routine discard of these grafts based solely on ureteral anatomy is not supported by the available evidence.

The paper emphasizes that acceptable outcomes are achievable through careful surgical technique, specifically:

Preservation of the vascularized periureteral tissue to prevent distal ureteral ischemia.
Tension-free ureteral implantation.
Appropriate stenting protocols.

While the findings suggest that these anatomical variants are viable for transplantation, the authors maintain a modest stance, noting that the "very low" certainty of evidence necessitates cautious interpretation. They call for prospective multicenter registries with standardized documentation to better validate these findings and reduce the current reliance on anecdotal experience.