Evaluation of Results of Diagnostic Ureteroscopy in Chronic Hemodialysis Patients

Introduction

Current semirigid ureteroscopes with advanced optics and lens systems allow easy manipulation and enable visualization of whole ureter easily and smoothly. ¹ Therefore, ureteroscopy has an important place in the diagnosis of ureteral disorders.

Diagnostic ureteroscopy (dURS) has been widely used in evaluation of gross hematuria and ureteral filling defects that cannot be diagnosed with radiological methods, determination of etiology of positive cytology obtained during cystoscopy and hydroureteronephrosis of unknown origin, prediagnosis of urinary tract urethelial carcinoma (UTUC) before nephroureterectomy, diagnosis and treatment of ureteral strictures, and diagnosis of congenital ureteral abnormalities. ^{2 –4}

Hemodialysis patients are more vulnerable to surgery due to their comorbidities, uremia, chronic anemia, and bleeding disorders, and surgeons must be careful more than ever in this patient group.

The aim of the present study was to evaluate the efficiency and safety of dURS in hemodialysis patients.

Materials and Methods

After obtaining approval of the Institutional Review Board, the data of consecutive patients who underwent primary dURS to determine etiologies of benign short ureteral stricture (<1 cm stricture length), tortuosity, or kinking (preventing flow of radio-opaque agent on retrograde pyelography to a large extent), unknown hydronephrosis or recurrent microscopic/macroscopic hematuria, or underwent dURS due to suspicion of UTUC (undetermined cytology with no evidence of a lesion on radiological imagings) between December 2004 and August 2014 were reviewed. Chronic hemodialysis patients (n = 76) (group I) and patients with normal estimated glomerular filtration rates (eGFRs) (n = 84) (group II) were included in the study. The etiologic factors in the patients requiring chronic hemodialysis were chronic glomerulonephritis (26.3%), type 1 or type 2 diabetes (25%), high blood pressure (19.7%), urological diseases (19.7%), and others (22.3%).

eGFR was calculated using the Chronic Kidney Disease (CKD) Epidemiology Collaboration formula. ⁵

The patients (n = 3216) with kidney or ureteral stones, acute renal failure, previous ureteral treatment (URS, antegrade percutaneous, laparoscopic or open ureteral surgery, Double-J stent placement) were excluded. Eighty-four patients whose eGFR levels had been determined and had dURS were included in the study as the control group. All patients had kidney function tests, urinalysis, ultrasonography, and computed tomography or magnetic resonance imaging before surgery when needed.

In all patients, the bladder was inspected systematically with a 17F, 30° cystoscope when the patient was in lithotomy position and under spinal or general anesthesia. Then dURS was performed using an 8.9/9.8F semirigid ureteroscope (Richard Wolf, Knittlingen, Germany). The initial maneuvers were performed for the diagnosis of ureteral lesions; the ureteroscope was introduced directly up to the renal pelvis through the benign ureteral lesions or ureteral strictures with safety guidewire. Usually, the surgeons do not use a guidewire when there is suspicion for UTUC. We tried to advance in the ureter without using a guidewire when there was a suspicion for UTUC (no touch technique). If the semirigid ureteroscope could not be introduced into the ureteral orifice or lumen, or more maneuvers were needed in the lumen, a safety guidewire (0.035 inch) was placed into the ureteral orifice through the ureteroscope, and the procedure was performed under the guidance of the hydrophilic safety guidewire. The ureteral orifice or ureteral stricture was dilated with balloon dilators when needed. Entire ureter was examined by endoscope to determine the presence of any strictures, kinking, or tumoral or mucosal lesions.

Any suspicious mucosal masses were biopsied with the cold cup biopsy technique. If present, the tumors (<1 cm, unifocal, no infiltrative lesion on radiological imagings) were biopsied and resected using Holmium: yttrium-aluminum-garnet laser at an energy setting of 8–10 J and a pulse frequency of f 10–15 Hz. A flexible ureterorenoscopy procedure was performed to patients with UTUC at follow-up period.

A Double-J stent or ureteral catheter was placed when dilatation, biopsy, or tumor ablation were done. All complications were graded according to modified Satava ⁶ and Clavien ⁷ classifications. The ureteral catheter was removed 1–2 days and the Double-J stent was removed 2–4 weeks after surgery. All operations were performed by surgeons with an experience of at least 3 years.

The statistical analysis was performed with PASW 18 (SPSS/IBM, Chicago, IL) software. Kolmogorov–Smirnov and P-P plot tests were performed to verify the normal range of the distribution of continuous variables. Descriptive statistics were shown as mean ± standard deviation for variables with a normal distribution and the number of cases and percent for the categorical variables. Student's t-test was performed for intergroup analyses of continuous variables. Categorical variables were analyzed with the chi-square test. p < 0.05 was considered as statistically significant.

Results

The patients were divided into two groups as dialysis patients and control patients. There were 76 patients in group I and 84 patients in group II. The mean operation time was longer in group I, and the difference between two groups was statistically significant (p = 0.01). Need for dilatation was higher in group I compared with group II (42.1% vs 15.5%, p = 0.01).

The mean eGFR was found to be 35.3 in patients who had dilatation, and it was 65.4 in the ones who did not have dilatation (p = 0.01). The mean urine outputs were 817 and 1572 mL in the ones who had dilatation and in the ones who did not have dilatation, respectively (p = 0.01).

Postoperative catheter placement rates were 71% and 23.8% in groups I and II, respectively (p = 0.01). There were no significant differences between two groups for gender, age, side of stone, or overall complication rates (Table 1). Intraoperative and postoperative complications were graded according to modified Satava and Clavien classification systems, respectively (Table 2).

Of five patients, 2 (2.6%) patients with high-grade UTUC in group I and 5 (5.9%) patients in group II underwent unilateral nephroureterectomy early after the diagnosis. Three patients with small low-grade UTUC were treated with complete endoscopic resection. Mean follow-up of all patients was 63.1 months. In patients with UTUC tumors, the 5-year metastasis-free survival rate after nephroureterectomy and endoscopy was 66.6% and 50%, respectively.

There were benign ureteral strictures in 42 (55.2%) patients in group I and in 20 (23.8%) patients in group II (p = 0.001). The strictures were located in the distal ureter in 23.8%, mid-ureter in 35.7%, and proximal ureter in 40.4% of the patients in group I; however, those rates were 40%, 40%, and 20%, respectively, in group II (p = 0.03). Other ureteral disorders such as kinking, dilated ureter, and extensive edema were seen in 10 (13.5%) patients in group I and in 4 (4.7%) patients in group II (p = 0.52).

The procedures were converted to open surgery in 1 (0.13%) patient in group I due to severe ureteral strictures. The majority of the intraoperative complications were modified Satava grades I or II. Only 1 (0.13%) patient in group I had a grade III injury. Hematuria was the most frequent postoperative complication (13%), particularly in group I (p = 0.01). Modified Clavien grade IV and V injuries were not seen in either group. Although fever and hematuria were the most common postoperative complications (Clavien II) in group I, Double-J stents or percutaneous nephrostomy tubes were not inserted into any patients for drainage.

Discussion

Hemodialysis patients are vulnerable to intraoperative and postoperative complications of surgery owing to their higher tendency for infection, sepsis, and bleeding. ^8,9 Longer bleeding time and higher rate of macroscopic hematuria due to platelet dysfunction impair vision during dURS, hence they may decrease the efficiency and safety of URS procedure. ⁹

Although some studies investigated efficiency and safety of minimally invasive surgical procedures in patients with CKD, ^10,11 no studies to date have investigated efficiency and safety of dURS in hemodialysis patients. Yuruk et al. ¹⁰ reported the stone-free rate of URS as 87.1% in patients with CKD. In our study, we found a similar result (85.5%). Doluoglu et al. ¹¹ showed that the URS procedure did not significantly affect renal function in CKD patients not requiring dialysis. The authors of both studies concluded that URS was efficient and safe in CKD patients treated for renal stones. In our study, 42.1% of hemodialysis patients needed balloon dilatation during URS. This rate is quite high when compared with other studies in the literature. A multicenter, randomized controlled study performed on patients without CKD found the rate of need for balloon dilatation to be approximately 25%. ¹² Our results indicated that ureteral strictures were more frequent in dialysis patients when compared with the controls. Higher rate of ureteral balloon dilatation in those patients increased the postoperative Double-J stent insertion rate (71%).

In case of long-lasting total obstruction, resulting from stones or other factors that prevent urine passage to the ureter, peristaltic activity increases first, and then the ureteral lumen narrows. If obstruction is not treated and urine passage is not provided, intraluminal pressure increases causing aperistalsis, which may result in narrowing of the ureteral lumen. ¹³ Recovery of ureteral peristalsis after treatment of obstruction takes some time. Erythropoietin (EPO) is one of the most important factors for recovery of ureteral peristalsis. Ninety percent of EPO is produced by kidneys alone and it allows erythropoiesis. ¹⁴ One of the factors that activate EPO release is urinary tract dilatation. ¹⁵ EPO release is not sufficient in dialysis patients owing to insufficient kidney reserve. This causes chronic anemia, and normal peristaltic activity of ureter may be absent in chronic dialysis patients with insufficient renal function with a urine output less than 200 mL/day. ¹⁶ There is a risk for ureteral stricture when urine does not pass through the lumen of ureter, and the ureter cannot gain its normal peristaltic activity. We suppose that this was the main reason for the increased need for balloon dilatation in our study.

There are some limitations of this study. It has a retrospective design, and the nature of retrospective study may be a potential source for selection bias. However, our study is the first study in the literature that investigated the results of dURS in hemodialysis patients.

Conclusions

Parallel to the technological advancements, it is possible to safely visualize the entire ureter with URS in hemodialysis patients as well as in other ones. However, we observed that balloon dilatation and postoperative stent placement rates were higher in those patients due to a high rate of intraluminal ureteral strictures.