Complications and clinical management of ultrasound-guided renal allograft biopsies

Color Doppler Guided in Early Renal Allograft Biopsy: A Safer and Non-Inferior Technique

BACKGROUND

This study compared a novel technique for renal allograft biopsy, color Doppler ultrasound-guided biopsy (CDUS-Bx), with routine ultrasound-guided biopsy (RUS-Bx).

METHODS

A retrospective review was conducted on 111 patients, with 42 undergoing CDUS-Bx and 69 undergoing RUS-Bx. Urologists used an 18-gauge automatic spring-loaded biopsy needle for all procedures. CDUS-Bx tissue collection was guided by identifying renal vessels with color Doppler mode.

RESULTS

Overall, the adequacy rate was 90.1%, with a higher number of glomeruli obtained in the CDUS-Bx group (25.6 ± 10.3 vs. 20.6 ± 11.3, P = .008). Acute tubular necrosis was the most frequent pathological diagnosis, with a higher prevalence in the CDUS-Bx group (69% vs 40.6%). T cell-mediated rejection had a lower incidence in the CDUS-Bx group (4.8% vs 21.7%), and antibody-mediated rejection was comparable between the 2 groups. The most common complication was microscopic hematuria, which was significantly less frequent in the CDUS-Bx group (48.7% vs 70.1%, P = .028), but there was no significant difference in the rate of gross hematuria between CDUS-Bx and RUS-Bx (11.9% vs 11.6%, P = .961). The number of cores was the only predictor of adequate biopsy, with a 93.2% adequacy rate after 3 cores of allograft biopsy. Multivariate analysis revealed that only the guiding type, CDUS-Bx, was associated with less microscopic hematuria (adjusted odds ratio 0.325, P = .018).

CONCLUSIONS

Color Doppler ultrasound-guided biopsy had comparable tissue adequacy to RUS-Bx, with a lower incidence of microscopic hematuria. These findings suggest that CDUS-Bx may be a safe and effective alternative to RUS-Bx for allograft biopsy.

Magnetic resonance imaging during warm ex vivo kidney perfusion

BACKGROUND

The shortage of donor organs for transplantation remains a worldwide problem. The utilization of suboptimal deceased donors enlarges the pool of potential organs, yet consequently, clinicians face the difficult decision of whether these sub-optimal organs are of sufficient quality for transplantation. Novel technologies could play a pivotal role in making pre-transplant organ assessment more objective and reliable.

METHODS

Ex vivo normothermic machine perfusion (NMP) at temperatures around 35-37°C allows organ quality assessment in a near-physiological environment. Advanced magnetic resonance imaging (MRI) techniques convey unique information about an organ's structural and functional integrity. The concept of applying magnetic resonance imaging during renal normothermic machine perfusion is novel in both renal and radiological research and we have developed the first MRI-compatible NMP setup for human-sized kidneys.

RESULTS

We were able to obtain a detailed and real-time view of ongoing processes inside renal grafts during ex vivo perfusion. This new technique can visualize structural abnormalities, quantify regional flow distribution, renal metabolism, and local oxygen availability, and track the distribution of ex vivo administered cellular therapy.

CONCLUSION

This platform allows for advanced pre-transplant organ assessment, provides a new realistic tool for studies into renal physiology and metabolism, and may facilitate therapeutic tracing of pharmacological and cellular interventions to an isolated kidney.

Complications of Percutaneous Kidney Allograft Biopsy: Systematic Review and Meta-analysis

BACKGROUND

Kidney biopsy is important to guide the management of allograft dysfunction but has a risk of complications. This review aimed to determine the incidence and risk factors of complications after kidney allograft biopsy.

METHODS

This is a systematic review and meta-analysis of randomized controlled trials, cohort studies, or case-control studies indexed on PubMed, Embase, Cochrane Central Register of Controlled Trials, World Health Organization International Clinical Trials Registry, and ClinicalTrials.gov, limited to the English language, from January 2000 to December 2020, including adult and pediatric kidney allograft biopsies. Primary outcomes were gross hematuria, bleeding requiring transfusion, and major complications (requiring interventions such as blood transfusion or surgical or radiological interventions).

RESULTS

The review included 72 studies (40 082 biopsies). The quality of included studies was suboptimal. Pooled rates of gross hematuria, bleeding requiring transfusion, and major complications were 3.18% [95% confidence interval (95% CI), 2.31-4.19], 0.31% (95% CI, 0.15-0.52) and 0.89% (95% CI, 0.61-1.22), respectively. Gross hematuria rates were lower in high-income compared with middle-income countries (2.59% versus 6.44%, P < 0.01) and biopsies performed by radiology as compared with nephrology departments (1.25% versus 3.71%, P < 0.01). Blood transfusion rates were lower in pediatrics than adults (0.0% versus 0.65%, P < 0.01). Major complications were lower in biopsies performed by specialists as compared with trainees (0.02% versus 3.64%, P < 0.01). Graft loss and mortality were extremely rare. Limitations included missing data, few randomized controlled trials, and possible publication bias.

CONCLUSIONS

The risk of complications after kidney allograft biopsy was low. Given the low quality of included studies, risk factors for complications should be further examined in future studies.

The Tangential Extraperitoneal Retrorenal Approach in Kidney Transplant Biopsy: An Observational Study to Assess Complication and Adequacy Rates

Introduction: Ultrasound-guided percutaneous kidney allograft biopsy is the gold-standard for pathology work-up. Recent studies postulate better safety and efficacy for tangential approaches, however, there is no recommendation regarding biopsy needle path. In this context, we previously described the unified tangential extraperitoneal retrorenal (TER) approach for standard allograft biopsy.

Methods: A single-center retrospective observational study evaluated safety and efficacy of the TER biopsy approach among 250 patients that underwent 330 ultrasound-guided kidney transplant biopsies between January 2011 and May 2020.

Results: The overall major complication rate was 0.56% per biopsy attempt (1.21% per biopsy) including blood transfusion, arterial embolization and bladder catheterization for gross hematuria in 0.28, 0.14 and 0.14% of biopsy attempts, respectively (0.61, 0.30 and 0.30% of biopsies, respectively). Minor complications included subcapsular and/or perinephric hematoma, superficial bleeding, arteriovenous fistula and gross hematuria in 12.6, 3.0, 2.5 and 1.4% of biopsy attempts, respectively (27.0, 6.4, 5.5 and 3.0% of biopsies, respectively). Sample adequacy rate was 86.7%, ranging from 82.2 to 94.1% if one or ≥two cores were analyzed, respectively. Residents and consultants yielded similar complication and adequacy rates.

Conclusion: According to current literature, ultrasound-guided TER kidney transplant biopsy is a safe and efficient approach eligible for nephrology training.

Rupture of Arteriovenous Fistula After Transplant Kidney's Biopsy: A Case Report

Background

To comment on the diagnosis and management of a rupture of arteriovenous fistula which is a rare but serious complication after transplant kidney’s biopsy.

Case Presentation

The report was performed on a serious case with rupture of arteriovenous fistula after transplant kidney’s biopsy in 108 Military Central Hospital. On the 7th day after biopsy, after moving out of the technical room for double J-stent removal, the patient suddenly felt a sharp pain in the transplanted kidney, followed by constant and increasing pain, also complete anuria. We revealed an arteriovenous fistula at the lower pole causing the parenchymal rupture and a large hematoma surround the graft and occupying the retroperitoneum. The emergency operation was done to remove the hematoma and suture the graft’s wound containing the arteriovenous fistula to stop the bleeding and eventually salvage the graft.

Conclusion

Rupture of arteriovenous fistula after transplant kidney’s biopsy is a rare but severe complication likely lead to graft loss. The patient should be carefully monitored with blood tests and Doppler ultrasound as a routine at least 2 weeks after biopsy.

MRI for diagnosis of post-renal transplant complications: current state-of-the-art and future perspectives

Kidney transplantation has developed into a widespread procedure to treat end stage renal failure, with transplantation results improving over the years. Postoperative complications have decreased over the past decades, but are still an important cause of morbidity and mortality. Early accurate diagnosis and treatment is the key to prevent renal allograft impairment or even graft loss. Ideally, a diagnostic tool should be able to detect post-transplant renal dysfunction, differentiate between the different causes and monitor renal function during and after therapeutic interventions. Non-invasive imaging modalities for diagnostic purposes show promising results. Magnetic resonance imaging (MRI) techniques have a number of advantages, such as the lack of ionizing radiation and the possibility to obtain relevant tissue information without contrast, reducing the risk of contrast-induced nephrotoxicity. However, most techniques still lack the specificity to distinguish different types of parenchymal diseases. Despite some promising outcomes, MRI is still barely used in the post-transplantation diagnostic process. The aim of this review is to survey the current literature on the relevance and clinical applicability of diagnostic MRI modalities for the detection of various types of complications after kidney transplantation.