Reflux Anuria After Prophylactic Ureteral Catheter Removal: A Case Description and Review of the Literature

Introduction

U reteral injury is an uncommon but feared complication of colorectal and gynecologic operations, occurring in 0.2% to 5.7% of cases. ^{1 –6} Prophylactic ureteral catheters are commonly used in complex cases to better identify the ureteral anatomy via visual (lighted catheters) or tactile (classic catheters) feedback. Recent literature, however, has shown that ureteral catheterization does not reduce the incidence of iatrogenic ureteral injury and may, in fact, cause its own complications. ^{6 –11}

Cases of hematuria, urinary tract infection, anuria, and direct ureteral injury during catheterization have led some authors to suggest that the risks of prophylactic catheters outweigh their potential benefits. ^1,9,12 Alternatively, several other studies have recognized that prophylactic ureteral catheters lead to earlier recognition and treatment of ureteral injuries and may improve outcomes. ^{6 –8,10, 11,13} Currently, the necessity for ureteral catheter placement is determined preoperatively by the operating surgeon based on expectations for difficulty and location of each individual procedure.

Transient ureteral obstruction after prophylactic catheter removal, also known as reflux anuria, has long been recognized as a potential complication of retrograde catheterization. ^{14 –16} Incidence ranges from 0% to 7.6% in various retrospective studies (Table 1). ^{1,6,8 –11,17 –19} The proposed mechanism of obstruction is urothelial edema secondary to catheter placement. ^14,16 Given the local obstruction associated with the urothelial edema, there is no retrograde flow of urine and “catheter-induced obstructive anuria” may be a more appropriate term for this phenomenon than reflux anuria. Unrecognized, obstructive anuria may lead to acute kidney injury and electrolyte abnormalities. These metabolic disturbances, if severe, may necessitate hemodialysis before resolution of the edematous obstruction. ¹⁰

This study describes a case of catheter-induced obstructive anuria after prophylactic ureteral catheter removal and reviews the current literature on this rare complication regarding presentation, treatment, and prevention.

Case Report

A 61-year-old man was found to have an intermediate-grade rectal adenocarcinoma on colonoscopic evaluation of hematochezia and was treated with neoadjuvant chemoradiation. Before definitive surgical management, bilateral 5F ureteral catheters were placed without complication. The operation included a laparoscopic-assisted low anterior resection and diverting loop ileostomy; hemodynamics remained stable throughout the procedure. The ureteral catheters were removed immediately after the operation. After surgery, urine output trended to zero and did not respond to fluid boluses. The patient remained anuric, and his creatinine level rose from 0.7 mg/dL at baseline to 6.3 mg/dL over subsequent days despite hydration. Fractional excretion of sodium was 2.6%. Renal ultrasonography did not reveal any acute hydronephrosis.

Because of high suspicion of postrenal obstruction, the patient was returned to the operating room on postoperative day 3 and underwent cystoscopy with placement of bilateral indwelling ureteral stents. Marked edema at the ureteral orifices was noted intraoperatively with brisk efflux of urine after stent placement. Over subsequent days, the patient underwent a postobstructive diuresis without electrolyte disturbances. His renal function returned to baseline, and he was discharged to home with stents in place. Indwelling stents were removed at 5 weeks postoperatively, and renal function remained stable.

Medline was searched for all relevant case reports, case series, and trials that included prophylactic ureteral catheters and described complications of their use with attention to catheter-induced obstructive anuria.

Discussion

Prophylactic ureteral catheters are commonly used in low abdominal and pelvic surgeries to better expose the ureteral anatomy and identify iatrogenic ureteral injuries. Although relatively innocuous, placement of ureteral catheters may be complicated by hematuria and urinary tract infection (UTI). Transient hematuria will occur in a majority of patients and typically resolves over a few days without need for intervention or sequelae. Recent studies have failed to show a positive correlation between prophylactic catheterization and UTI, despite the theoretical risk ^9,19 ; rather, Nam and Wexner ¹⁸ showed a significantly reduced incidence of UTI in catheterized vs noncatheterized patients.

Anuria after the use of prophylactic ureteral catheters in a complicated pelvic surgery is another potential complication that often proves difficult to evaluate and treat. The surgeon faces a differential diagnosis, including ureteral injury, transient obstruction (catheter-induced obstructive anuria), and acute tubular necrosis (ATN). Unless there is a high suspicion of bilateral ureteral injury, iatrogenic injury will not typically manifest with a total absence of urine output, like that seen in our patient. ATN and obstructive anuria will have similar presentations, but cases of ATN generally will involve intraoperative hypotension and tissue damage.

Obstructive anuria cases will not necessarily have these variable hemodynamics. Urine output in obstructive anuria may vary from day to day with a low specific gravity, but in ATN, specific gravity is normal and urine output remains low until the tubular injury starts to resolve. ¹⁰ Both diagnoses will show progressive renal failure in the acute phase. Renal ultrasonography may indicate obstructive anuria if hydronephrosis is seen, but the acute nature of the obstruction often does not allow the development of hydronephrosis, as demonstrated by our patient. Our patient remained hemodynamically stable throughout his course and did not have other risk factors for ATN; therefore, there was a high suspicion for postrenal obstruction.

The pathophysiology of catheter-induced obstructive anuria is poorly understood. Studies from the 1950s and 1960s have purported the theory of local urothelial edema secondary to catheterization leading to obstruction and anuria after catheter removal. ^14,16 This reaction is likely secondary to the release of inflammatory mediators with urothelial manipulation, but further studies are needed. In cases of renal obstruction, renal blood flow decreases and then increases above baseline after resolution of the obstruction. Resistive index inversely increases in acute obstruction and decreases in the postobstruction phase. In ATN, both renal blood flow and resistive index remain normal, therefore providing another possible means of differentiating it from obstructive anuria. Prompt recognition of obstructive anuria is needed to quickly institute treatment.

The mainstay of treatment for obstructive anuria is supportive therapy. Electrolytes and renal function should be monitored closely and an indwelling urinary catheter maintained to follow urine output. Hemodialysis may be necessary for severe cases of hyperkalemia, acidosis, or fluid overload. In a series by Chahin and associates, ¹¹ two of four patients with obstructive anuria needed temporary hemodialysis before resolution of their anuric renal failure. For persistent anuria and progressive renal failure, series by Sheikh and Khubchandani ¹⁰ and Leff and colleagues ⁶ provide anecdotal evidence supporting cystoscopy and again performing stent placement in the ureters to alleviate the edematous obstruction.

Because of progressive uremia in our patient, the decision was made to perform a second cystoscopy and place indwelling ureteral stents. Subsequently, his uremia quickly improved without the need for invasive line placement and hemodialysis treatments. In all available case series, patients with catheter-induced obstructive anuria who were treated with indwelling stent placement have not needed hemodialysis. Therefore, we suggest that acute kidney injury in cases of obstructive anuria should not be allowed to progress to necessitating dialysis without attempts at endoscopic management.

Recent attention has focused on preventative measures to reduce complications of obstructive anuria. No patient predisposing factors have been found to date. Bothwell and coworkers ⁸ were able to eliminate reflux anuria by performing 24-hour staged removal of the ureteral catheters postoperatively (Table 1). Although anuria has still been reported after staged catheter removal, the stepwise removal shows a trend toward reduced obstructive anuria incidence. ¹⁰ Conversely, Kuno and colleagues ⁹ report a series of 469 gynecologic patients receiving prophylactic ureteral catheters with immediate postoperative removal and no reported anuria. Further prospective studies are needed to determine the impact of staged catheter removal on anuria incidence and possible predisposing patient factors.

Levine and associates ²⁰ report the same phenomenon of ureteral obstruction observed with use of large-diameter (8F or larger) antegrade ureteral catheters. Stamey ¹⁶ postulated that obstructive anuria is caused by the tissue reaction to large catheters pressing outward on the ureter. Under this assumption, smaller-diameter catheters will result in fewer anuric cases after prophylactic catheterization. No studies have been performed to date looking at the incidence of obstructive anuria with various catheter sizes. Newer lighted ureteral catheters allow for the passage of a thin fiberoptic wire up the ureter. Commercially available lighted catheters from Cook Medical (Bloomington, IN) and Stryker Endoscopy (San Jose, CA) are 5F and 6F, respectively, however, and provide no size benefit over commonly used 5F open-ended catheters. Studies are needed to analyze the potential reduction of anuria with smaller-diameter lighted ureteral catheters.

Our patient underwent an uncomplicated cystoscopy with bilateral placement of 5F catheters. Despite their relatively small diameter, catheter-induced obstructive anuria developed after immediate removal of both catheters. The patient's acute kidney injury progressed before a second cystoscopy with insertion of indwelling ureteral stents. Our institution has now changed to a staged removal protocol to reduce prophylactic catheter complications. Further evaluation is needed to determine if the change in protocol affects the incidence of obstructive anuria.

Conclusions

Prophylactic ureteral catheters have a proven role in complicated colorectal and gynecologic surgeries. Catheters are not innocuous, however, and may cause hematuria, infection, oliguria, or anuria. Cases of catheter-induced obstructive anuria can progress to severe renal failure necessitating hemodialysis if endoscopic management with indwelling stent placement is not performed promptly. Although no proven methods for prevention exist, staged removal of stents may reduce the incidence of obstructive anuria.