Sonography: a useful tool to detect the mechanical causes of renal transplant dysfunction

Adverse Clinical Outcomes among Inflammatory Bowel Disease Patients Treated for Urinary Tract Infection

Background: Urinary tract infection (UTI) is the most common urologic complication among patients with inflammatory bowel disease (IBD). However, data regarding UTI outcomes in this population are scarce. We aimed to evaluate adverse outcomes of UTI among patients with IBD. Methods: This was a retrospective cohort study of consecutive adult patients who visited the emergency room (ER) at Sheba Medical Center due to a UTI between 2012 and 2018. Data included demographic and clinical variables. UTI cases were extracted using ICD-10 coding. Results: Of 21,808 (ER) visits with a UTI, 122 were IBD patients (Crohn’s disease—52, ulcerative colitis—70). Contrary to non-IBD subjects, patients with IBD had higher rates of hospitalization, acute kidney injury (AKI) and 30 day-recurrent hospitalization (59.3% vs. 68.9%, p = 0.032; 4.6% vs. 13.9%, p < 0.001; 7.3% vs. 15.6%, p = 0.001, respectively). Among patients with IBD, advanced age (p = 0.005) and recent hospitalization (p = 0.037) were associated with increased risk for hospitalization, while hydronephrosis (p = 0.005), recent hospitalization (p = 0.011) and AKI (p = 0.017) were associated with increased 30-day recurrent hospitalization. Neither immunosuppressants nor biologics were associated with UTI outcomes among patients with IBD. Conclusions: Patients with IBD treated for a UTI had higher rates of hospitalization, AKI and 30-day recurrent hospitalization than non-IBD patients. No association was observed between immunosuppressants or biologics and UTI outcomes.

Urothelial Carcinoma Detected by Ultrasonography in a Renal Transplant Recipient

Urothelial cell carcinoma in renal transplant recipients has been rarely reported. Here, we report a case of high-grade papillary urothelial carcinoma in a renal transplant recipient who presented with hematuria. Sonographic evaluations (gray-scale ultrasonography, Doppler imaging, and strain sonoelastography) helped with diagnosis in our initial approach to the patient. Computed tomography was performed to confirm solid ureteral masses and staging of the disease. The patient, who underwent nephro-ureterectomy of the graft kidney, had that kidney for 6 years, 6 months. After surgery, the patient was symptom free and without evidence of recurrence or metastasis in 3 years of follow-up. Sonographic examinations have an important role in the evaluation of urothelial carcinoma of transplanted kidneys.

Acute Kidney Injury in Transplant Setting: Differential Diagnosis and Impact on Health and Health Care

Acute kidney injury (AKI) is common in kidney transplant recipients. In addition to the usual causes of AKI in native kidneys, certain features and risk factors are unique to kidney allografts. In this article, we will present an overview of the common transplant-specific AKI etiologies that include increased susceptibility to hemodynamic-mediated AKI, acute rejection, medication-induced AKI, recurrence of native kidney disease, infections, urinary tract obstruction, vascular thrombosis and post-transplant lymphoproliferative disorder. AKI is independently associated with allograft loss and patient mortality. It is, therefore, prudent for transplant centers to address it as a major quality measure.

Novel imaging techniques in acute kidney injury

Imaging of the kidneys can provide valuable information in the work up and management of acute kidney injury. Several different imaging modalities are used to gather information on anatomy of the kidney, to rule out obstruction, differentiate acute kidney injury (AKI) and chronic kidney disease and to obtain information on renal blood flow and GFR. Ultrasound is the most widely used imaging modality used in the initial work up of AKI. The utility of contrast enhanced computerized tomography and magnetic resonance imaging is limited because of toxicities associated with contrast agents used. In this review the basics of ultrasonography are reviewed with an emphasis on findings in AKI. The new developments in different imaging modality and their potential uses in AKI are reviewed as well.

Obstructive uropathy and acute renal failure due to ureteral calculus in renal graft: a case report

INTRODUCTION

Obstructive uropathy caused by kidney stones is quite rare in transplant kidneys.

CLINICAL CASE

The authors report the case of a patient, previously gastrectomized for gastric carcinoma. He underwent renal transplantation using uretero-ureterostomy, and presented an episode of acute renal failure 7 years after surgery. Ultrasound (US) examination showed no sign of rejection but allowed detection of moderate hydronephrosis in the transplant kidney. Subsequent computed tomography (CT) revealed a kidney stone in the middle ureter at the crossing of the iliac vessels. The patient therefore urgently underwent percutaneous nephrostomy of the graft and recovered diuresis and renal function. The patient was transferred to the Transplant Center where he underwent ureterotomy with removal of the stone and subsequent ureteropyelostomy. Also transureteral resection of the prostate (TURP) was performed due to urinary retention of prostatic origin. Histological examination showed prostate carcinoma, Gleason stage 3, which was treated conservatively using radiotherapy without suspension of the administered low dose of immunotherapy.

DISCUSSION

Calculosis is one of the least common causes of obstructive uropathy in transplant kidneys. In the described case, US examination performed after onset of renal insufficiency led to subsequent radiological investigation and resulting interventional procedures (nephrostomy and surgical removal of the stone) with complete recovery of pre-existing renal function.

Reversed diastolic flow in the renal transplant: perioperative implications versus transplants older than 1 month

OBJECTIVE

The purpose of our study was to evaluate the causes, waveform morphology, and clinical outcomes of high-resistance reversed diastolic flow in transplanted kidneys.

MATERIALS AND METHODS

To identify patients with reversed diastolic flow, we performed a review of 5,089 renal transplant Doppler sonograms obtained over a 10-year period. Waveform morphology was correlated with surgical-histologic findings and clinical outcomes.

RESULTS

Fifty-nine patients (33 male, 26 female; age range, 14-69 years) with reversed diastolic flow fell into three chronologic groups: acute group (six patients), transplant < 24 hours; perioperative group (34 patients), transplant < or = 30 days; and long-term group (19 patients), transplant > 30 days. Acute reversed diastolic flow was associated with higher likelihood of graft survival (p = 0.001, Fisher's exact test) compared with reversed diastolic flow discovered in the perioperative or long-term group. In the acute group, hematoma, acute tubular necrosis, renal vein thrombosis, and vascular kink produced reversed diastolic flow. The causes of reversed diastolic flow for the perioperative group were acute tubular necrosis, rejection, and renal vein thrombosis; for the long-term group, reasons for diastolic reversal were rejection, glomerulosclerosis, low cardiac output, and diabetic nephrosclerosis. The causes of reversed diastolic flow were not differentiated by waveform morphology.

CONCLUSION

The causes of reversed diastolic flow cannot be distinguished by waveform morphology. Patients with reversed diastolic flow < 24 hours after transplantation warrant emergent exploration because correction of treatable causes may lead to recovered function. Long-standing renal transplants with reversed diastolic flow are not likely salvageable.

Renal transplant failure due to urologic complications: Comparison of static fluid with contrast-enhanced magnetic resonance urography

PURPOSE

Postrenal reasons of renal transplant failure can be assessed by magnetic resonance urography. This study was designed to retrospectively compare the diagnostic accuracy of static fluid (T2-)MRU compared to contrast enhanced (CE-)MRU in patients with renal transplant failure.

MATERIAL AND METHODS

Thirty-five consecutive patients (14 female, 21 men; mean age 48.6 years) with renal transplant failure and sonographically detected hydronephrosis were examined both with T2-MRU as well as CE-MRU resulting in 39 MRU examinations. MRU was performed both using T2-weighted HASTE-sequence (T2-MRU) as well as Gadolinium-enhanced 3D-FLASH-sequence (CE-MRU) on a 1.5-T clinical MRI scanner (Magnetom Vision, Siemens Medical Solutions). Subjective image quality of resulting maximum intensity projection was assessed in consensus by two readers blinded to the final diagnosis, using a five point scale. MRU findings were correlated to sonography, operative results or clinical follow up.

RESULTS

CE-MRU yielded a sensitivity of 85.7% (T2-MRU 76.2%), and a specificity of 83.3% (T2-MRU: 73.7%), however statistical significance was not reached. The subjective image quality was significantly better in CE-MRU.

CONCLUSIONS

Only concerning subjective image quality CE-MRU proved superior to T2-MRU. Yet, there was no significant difference in diagnostic accuracy between T2- and CE-MRU. Thinking of incipient nephrogenic systemic fibrosis, T2-MRU can be used as reliable alternative in patients with decreased renal transplant function due to urological complications.

Imaging of the renal transplant: comparison of MRI with duplex sonography

Renal transplantation is an established treatment for patients with end-stage renal disease. Many causes of graft dysfunction are treatable, making prompt detection and diagnosis of complications essential. Sensitive, noninvasive imaging procedures, which do not use iodinated contrast media, are therefore highly desirable to evaluate graft function. Duplex sonography (US) has traditionally been the initial investigation of graft dysfunction. US offers many advantages, particularly during the postoperative period, when it can be performed portably regardless of renal function and can guide percutaneous procedures. However, US lacks specificity in assessing hydronephrosis, cannot differentiate parenchymal causes of dysfunction, and may have difficulty assessing transplant vessels. Recently comprehensive magnetic resonance imaging (MRI) protocols including MR urography, gadolinium-enhanced MR angiography, and MR renography have evolved as a "one-stop" diagnostic technique in the evaluation of the entire graft and peritransplant region. Multiplanar capabilities enable MRI to identify the site of urinary obstruction and assess renal vessels in their entirety. The evolving technique of MR renography may also differentiate parenchymal causes of dysfunction. By combining these three components into a single examination, further information may be obtained regarding the graft when compared with US and other conventional studies, with improved patient convenience, less morbidity, and a potential cost saving.

B-mode sonography in acute renal failure

B-mode sonography is an extremely useful and cost-effective method to eliminate urinary obstruction as a cause of acute renal failure and should be performed on all patients in whom obstruction is likely or in whom the cause of renal failure is not apparent. The threshold should be reduced in patients with solitary kidneys and sonography is probably indicated in all transplant patients. Sonography has very little utility in the management of other patients with acute renal failure. Although sonographic changes do occur in acute tubular necrosis, they are difficult to detect in the absence of baseline studies and are nonspecific.

Ultrasound score is more predictive than serum creatinine in assessment of cellular rejection in cynomolgus monkey renal allografts

RATIONALE AND OBJECTIVES

To investigate whether ultrasound (US), in particular the use of an ultrasound scoring system, can provide more diagnostic information than clinical parameters, such as serum creatinine, for the diagnosis and determination of the degree of cellular rejection in renal allografts in the cynomolgus monkey (Macaca fascicularis).

METHODS

Sixty-eight cynomolgus monkeys with life-supporting renal allografts were examined with a 7.5MHz linear ultrasound transducer. One-hundred fifty two-dimensional, spectral, and power Doppler examinations were performed and four ultrasound parameters, percentage increase in graft volume, cortical thickness, resistive index (RI) of the renal arcuate artery, and power Doppler (PD) scores were recorded from serial examinations. An ultrasound score was assigned to each graft based on the number of those parameters that were abnormal; a score of 1 indicated that all four were normal, and a score of 5 that all four were abnormal. Each parameter and the combined score were compared with serum creatinine values and histology and evaluated statistically using Spearman rank correlation.

RESULTS

In animals with dysfunctioning allografts (serum creatinine elevations >200 micromol/L), Spearman rank correlation showed a significant correlation between the US score and the histology score: between 200 and 500 micromol/L, r = 0.309, P = 0.046, n = 31 and if > 500 micromol/L, r = 0.486, P = 0.005, n = 30. In those same animals, no correlation could be shown between serum creatinine values and the US score or between the serum creatinine values and the histologic diagnosis. In contrast to the US score, single ultrasound parameters were not found to correlate to histologic findings.

CONCLUSION

The application of ultrasound imaging in nonhuman primate renal transplant models provides valuable information concerning the presence and severity of cellular rejection in cases of graft dysfunction and the US score has a better predictive value of histology than serum creatinine values alone.

Ultrasonography in renal transplantation

Sonography is a simple, inexpensive, and readily available imaging modality that has become an essential component of the management of renal transplantation. It is indicated in almost all patients with acute renal failure and also is useful in the evaluation of pain, infection, and hematuria and the performance of percutaneous biopsy. Although many aspects of sonography are similar in native and transplanted kidneys, there are important differences and problems unique to the renal allograft, which form the basis for this review. The anatomy of renal transplantation and changes that accompany parenchymal disorders are discussed, but particular attention focuses on problems related to the urinary tract, fluid collections, and vascular disorders. By becoming more familiar with transplant sonography, nephrologists will be better able to incorporate this indispensable tool into the care of their patients.

Postural renal transplant obstruction: a case report and review of the literature

A 48-year-old woman underwent cadaveric renal transplantation for end-stage renal failure secondary to polycystic kidney disease. Nine months after transplantation, intermittent renal dysfunction and severe graft hydronephrosis developed despite the presence of a ureteric stent. A Tc-99m MAG3 scan performed with the patient standing showed complete transplant obstruction. Rapid tracer clearance with progressive bladder filling was present when the patient was imaged in the supine position. Ureteric obstruction is the most common urologic complication of renal transplantation. However, postural ureteric obstruction has been described only rarely. This case indicates that posture may affect ureteric patency and highlights this potential pitfall in the evaluation of intermittent graft dysfunction by diuretic renography.

Ureteral obstruction in a transplant kidney caused by an ovarian tumor

Ureteral obstruction in the transplant recipient can provide a diagnostic challenge. We report a case of ureteral obstruction 5 years after cadaveric renal transplantation due to an ovarian tumor. Magnetic resonance imaging provided essential anatomic information that eventually led to the diagnosis. To our knowledge, this is the first reported case of ureteral obstruction in a transplant kidney caused by an ovarian tumor.