CT-guided Retrograde Urography as a Diagnostic Tool for Post-kidney Transplantation Evaluation: A Case Report

The vast majority of urological complications occur at the ureterovesical junction and usually occur early after transplantation. The aim of this study is to enhance the quality of medical care provided to patients who undergo kidney transplantation. Cystography was conducted on renal transplant recipients utilizing computed tomography. The utilization of changes in the patient’s position and reconstructed images of the bladder can serve as a diagnostic tool to assess the normal functioning of the urinary tract system subsequent to kidney transplantation. To ensure adequate ﬁ lling of the bladder and ureter, it is necessary to introduce varying amounts of contrast medium through the urinary catheter into these structures. This diagnostic procedure aims to verify the existence of stenosis or leakage occurring at the vesicoureteral junction. The evaluation and diagnosis of urinary tract problems subsequent to kidney transplantation can be eﬀ ectively conducted. Furthermore, it has the potential to mitigate the adverse eﬀ ects and alleviate the strain on the renal system resulting from the administration of contrast agents in computed tomography urography. CT-guided cystography can enhance the medical quality and comfort of Kidney transplantation patients.


Introduction
Kidney transplantation (KTX) is widely recognized as the most ef icacious therapeutic intervention for individuals af licted with chronic kidney disease [1].Can offer patients diagnosed with end-stage renal disease superior long-term survival rates and improved quality of life compared to maintenance hemodialysis.Major urologic complications (MUCs) are associated with increased morbidity and graft loss following KTX, particularly after episodes of rejection [2,3].MUCs are a frequently observed complication following KTX.MUCs occur in approximately 9% of kidney transplants [4].MUCs were de ined as instances of urinary leakage, ureteral stricture, bladder outlet obstruction (BOO) (internal and external), graft stones, and vesicoureteral re lux [5][6][7].Among them, the ureterovesical stricture is due to technical errors or ureteral blood vessels.
MUCs after KTX will cause complications in patients and endanger the function of the transplanted kidney.The vast majority of urological complications occur at the ureterovesical junction (UVJ) and usually occur early after transplantation [8,9].
Early detection and treatment of BOO is essential for maintaining long-term graft function.Indeed, adequate longterm graft function depends on low-pressure urine storage and effective bladder emptying [10,11].In the case report, cystography was performed using computerized tomography (CT) to diagnose the normalcy of the urinary tract system after KTX.The patient's position change and reconstructed images were utilized for this purpose.

Case presentation
A 57-year-old male patient with a medical history of recurrent ureteral obstruction and hydronephrosis underwent ureteric reconstruction and transplantation of the native ureter into the transplanted kidney.https://doi.org/10.29328/journal.jcmei.1001028 CT cystography is a modi ied form of the conventional luoroscopic cystogram.In contrast to CT urography, where anterograde opaci ication of the urinary collecting system is used, retrograde instillation of contrast into the patient's bladder is employed, followed by imaging of the pelvis using CT.
The patient experienced acute tubular necrosis, acute rejection, and the presence of a residual thrombus within one week after KTX.Despite the placement of prophylactic ureteral stents post-surgery and the removal of the thrombus through cystoscopy, the observed urine low did not meet the anticipated levels.This raised concerns regarding the possibility of UVJ stenosis or leakage.As a result, a consultation was made with the radiology department to conduct CT cystography.
Radiologists utilized CT imaging with the Philips Brilliance 64-slice scanner to perform cystography.First, a reconstructed coronal plane image along the UVJ was obtained prior to contrast injection, as depicted in Figure 1.Subsequently, a dilute solution of iodinated contrast agent (ULTRAVIST ® ) was perfused through the urinary catheters.The ratio of iodinated contrast (300 mgI/mL) to water is 1:1.5.To assess the presence of stenosis or leakage at the UVJ and the smoothness of the ureteral stent and normal drainage, the following procedure was performed.A total of 160ml of luid, divided into three equal portions of 60ml, 60ml, and 40ml, was used to ill the bladder and the ureter.The patient was positioned in three different ways: lying lat, lying oblique, and lying on the right side.Changes in angles were observed to con irm the presence of stenosis or leakage at the UVJ and to assess the smoothness of the ureteral stent and normal drainage.

Results
A contrast medium of 60mL was retrogradely administered through the urinary catheters into the bladder and ureter in order to enhance visualization of the stricture of the UVJ, as depicted in Figure 2.
The patient's left side should be elevated by 45 degrees, followed by the injection of 60mL of contrast medium to ill the bladder and ureter.This procedure allows for a clear observation of the narrowness of the UVJ, as depicted in Figure 3.The patient's position was altered to a prone position on the table, with the left side elevated by 60 degrees, while simultaneously administering a continuous infusion of 60mL of contrast medium.It can be observed from Figure 4 that the contrast medium has been administered to the renal pelvis of the transplanted kidney.
Following the excretion of the contrast medium from the bladder, a notable decrease in the volume of the contrast medium was observed in both the renal pelvis and bladder.This observation provides empirical evidence that demonstrates the functional adequacy of the urinary system following KTX, as depicted in Figure 5.
The bladder is fully illed with a retrograde contrast agent infusion, extending through the ureteral stent and     reaching the transplanted renal pelvis.After implementing adjustments in body position and conducting image reconstruction, it can be ascertained that there is no evidence of leakage at the anastomosis site between the bladder and ureter.Additionally, the drainage function of the ureteral stent appears to be functioning normally.
One month later, the patient's daily urine output was 1000-1300 mL, and he experienced nocturia 3-4 times per night.Two weeks later, the double-J stent was removed through cystoscopic retrograde pyelography, and the patient was able to resume a normal life.

Discussion
Urinary tract system examinations are commonly performed utilizing a range of diagnostic techniques, such as intravenous urography (IVU), computed tomography urography (CTU) with contrast agent administration, cystoscopy, and retrograde pyelography (RP).
Compared to CT-guided cystography, IVU exhibits a lengthier examination duration and lacks the capability to capture images from multiple angles.Cystoscopy, despite its relative ease of execution, can induce pain and discomfort in patients and is associated with potential risks such as urinary tract infection or bleeding [12,13].On the contrary, CTU necessitates the administration of a greater contrast dosage, which could potentially place an additional burden on KTX postoperatively and may not yield urinary tract images in a timely manner [14,15].However, this case is not representative of all transplant recipients, as it is well-known that UVJ anastomosis methods are different.

Conclusion
Prompt diagnosis and treatment are essential in cases of renal transplant obstruction.Once the presence of ureteric obstruction is con irmed or strongly suspected, it is imperative to promptly initiate urinary diversion in order to mitigate potential kidney damage.Once renal function has shown improvement, the medical team proceeds with the de initive treatment of the obstruction in the ureter.
CT-guided cystography, utilizing CT guidance, offers the potential to integrate the bene its of the aforementioned examinations.This technique allows for the effective evaluation and diagnosis of urinary tract issues following KTX, while also mitigating the potential harm associated with contrast media injection during CTU and reducing the risks associated with invasive examinations.Consequently, the implementation of CT-guided cystography can signi icantly enhance the overall medical quality of KTX patients.

Figure 1 :
Figure 1: (a) A reconstructed coronal plane image was obtained at the UVJ without the use of contrast injection.(b)(c) Acquire an image of the UVJ.

Figure 3 :
Figure 3: (a) The patient's left side was elevated by 45 degrees.(b) Demonstrate the UVJ more prominently.(c) Backfl ow of contrast agent into the transplanted kidney.(Indicated by the red circle).

Figure 4 :
Figure 4: (a) Position the patient in a prone position, with a 60-degree inclination on the lower right side and upper left side.(b) The UVJ is clearly evident.(c) Retrograde fl ow of the contrast agent into the transplanted kidney.(Indicated by the red circle).

Figure 5 :
Figure 5: (a) The patient was positioned in a right lateral posture subsequent to the introduction of the contrast agent into the bladder.(b)(c) A notable reduction in the concentration of the contrast agent was observed in both the bladder and renal pelvis exhibited a signifi cant decrease (indicated by the red circle).

Figure 2 :
Figure 2: (a) A reconstructed coronal plane image was obtained at the UVJ following contrast injection.(b)(c) The stricture of the UVJ is clearly observable.