Syllabus - CTisus.com CT Scanning

Additional Resources ❯ Syllabus ❯ Bladder: Role of CT in Postoperative Evaluation of Patients Undergoing Urinary Diversion

Role of CT in Postoperative Evaluation of Patients Undergoing Urinary Diversion

1. Satomi Kawamoto1 and

2. Elliot K. Fishman

Abstract

OBJECTIVE. The purpose of this article is to discuss and illustrate the MDCT findings of potential complications after cystectomy and urinary diversion.

CONCLUSION. Multiple complications may occur after urinary diversion. Tumor recurrence is a major concern in patients with bladder cancer. CT has an important role in postoperative evaluation of patients with urinary diversion to identify correctable causes early to prevent deterioration in renal function and detect tumor recurrence in patients who had bladder cancer.

Introduction

Urinary diversion is a well-established urologic procedure. The main indication for urinary diversion is to improve or replace the function of the urinary bladder in patients with bladder cancer, neurogenic bladder dysfunction, detrusor overactivity, and chronic inflammatory diseases of the bladder. For treatment of muscle-invasive and refractory superficial bladder cancer, radical cystectomy with a urinary diversion is considered the reference standard. The three most common types of urinary diversions are the incontinent, cutaneous diversion (conduit); continent, cutaneous catheterizable reservoir (pouch); and continent, urinary diversion to the intact native urethra (orthotopic neobladder) [1]. During the past decade, there has been increasingly frequent use of orthotopic reconstruction [2].

Multiple complications may occur after urinary diversion. They may be classified as early and late complications and may also be classified as directly or not directly related to the conduit or neobladder itself.

Early complications (< 30 days after surgery) include bowel complications (ileus, obstruction, anastomotic leak, ischemia), infections (urinary tract infection–pyelonephritis, abscess), postoperative fluid collections (urinomas, hematomas, lymphoceles), and urinary tract complications (anastomotic leak, obstruction, ischemia) [3]. Chang et al. [4] reported that the overall early complication rate after radical cystectomy was 30.9%, with postoperative ileus being the most common minor complication, affecting 54 (18%) of 304 patients.

Late complications include stone formation, infection, transmission of high bladder pressure to the upper urinary tract (reflux or functional obstruction), and physical obstruction at any site, most commonly at ureteroenteric anastomosis. These complications may cause deterioration in renal function [3]. Correctable causes should be identified early to prevent deterioration in renal function. CT has an important role in detection of postoperative complications and recurrent tumor in patients with urinary diversion. The objective of this article is to discuss and illustrate the normal and abnormal findings after urinary diversion on MDCT.

CT Technique

CT was performed with 16-MDCT or 64-MDCT scanners. For patients referred for routine follow-up, CT was performed with oral and IV contrast administration at the venous and excretory phases. When complications or recurrence of tumor of the urinary tract were suspected after urinary diversion, CT was performed using a CT urography protocol, which typically included unenhanced, corticomedullary, venous–nephrographic, and excretory phases. Multiplanar reformation images were created routinely, and 3D images were created when requested by the referring physician.

Normal Postoperative Appearance After Urinary Diversion

The anatomy of the urinary diversion may vary depending on the types of urinary diversions. In ileal conduit urinary diversion, ureters extend to the ureteroileal anastomosis, with ileal conduit extending to the urostomy (Figs. 1 and 2). In orthotopic neobladder urinary diversion, neobladder is seen extending to the midline lower pelvis and anastomosed to the urethra (Figs. 3 and 4A, 4B). The ureters may be anastomosed to a segment of the bowel in a separate (Bricker procedure) or conjoined (Wallace procedure) fashion (Figs. 1 and 3). In the classic Bricker procedure, each ureter is sutured to the lateral aspect of the ileal conduit. In the Wallace procedure, both ureters are conjoined and sutured to the ileum. In right colonic urinary diversion, the colonic pouch is seen in the right lower quadrant. Intrarenal collecting systems are typically slightly wide after urinary diversion, either due to prior obstruction or to reflux.

Urinary Leakage and Rupture

Urinary leakage from anastomosis is an uncommon early complication and previous studies reported incidence of up to 1.1% [5]. On CT, intraperitoneal urinary leak from ileal conduit or neobladder may be detected as extravasation of contrast material into the peritoneal space. Ascites may contain radiodense fluid, reflecting extravasated contrast material (Fig. 5A, 5B, 5C). Associated ileus may also be seen. If excretory images are not obtained, extravasation may not be seen. The leakage may also emanate from the anterior portion of the conduit that may not be entirely distended with contrast material.

Postsurgical Fluid Collection/Hematoma

Postsurgical fluid collections such as urinoma, abscess, hematoma, and lymphocele can be seen as early postoperative complications. On CT, hematoma is seen as a dense fluid collection (Fig. 6A, 6B) that typically decreases in attenuation over time. The use of IV contrast enhancement helps to differentiate fluid collection, such as hematoma, from vascular complications, such as pseudoaneurysm (Fig. 6A, 6B).

Obstruction/Stricture at Anastomosis or Reservoir

The incidence of ureteral stricture after radical cystectomy with urinary diversion is reported with rates varying from 3% to 10% in the literature [6]. Ureteral ischemia is the most common cause of ureteroenteric anastomotic stricture. Ureteroenteric obstruction often is silent clinically and is detected by increased serum creatinine or on follow-up imaging studies [7]. Most cases of ureteroenteric anastomotic strictures occur within the first 1–2 years postoperatively but can occur several years after surgery [7]. On CT, ureteral stricture is usually associated with hydronephrosis and delayed contrast excretion (Figs. 7A, 7B, 7C and 8A, 8B, 8C). The involved ureteral wall may be thickened, and it may be difficult to differentiate a stricture with fibrosis from recurrent tumor.

Urinary diversion–enteric fistula is an uncommon complication after radical cystectomy and urinary diversion (Fig. 9A, 9B) and reportedly occurred in 12 (2.2%) of 553 patients with a mean follow-up of 28.4 months [6].

Stone Formation

Patients who undergo urinary tract diversion procedures have an increased risk of developing urolithiasis, particularly patients with an ileal conduit. In patients after urinary diversion, the underlying cause of urinary stone formation is multifactorial and includes metabolic, structural, infectious, and idiopathic factors. Most stones are primarily of struvite and are thus thought to be secondary to infection by urea-splitting organisms [8]. Stones may be seen within the kidney, ureter, or ileal conduit or in multiple locations (Fig. 10). The incidence of upper tract stones after ileal conduit diversion as reported in the literature varies from 2.6% to 13.4% [8].

Urinary Tract Infection

Normal urothelium has several defense mechanisms against bacteria, such as voiding function to wash out bacteria and inhibitory action against bacterial adherence [7]. After urinary diversion, some of the normal defense mechanisms are impaired and patients are susceptible to bacterial infection [7]. Madersbacher et al. [9] reported that clinically evident urinary tract infection occurred in 30 (23%) of 131 patients with ileal conduit who were followed for more than 5 years, and uro-sepsis occurred in five patients (3.8%). CT findings of upper urinary tract infection include pyelonephritis and renal or perirenal abscess (Fig. 11A, 11B).

Deterioration of renal function may occur because of recurrent urinary tract infection, stone formation, and obstruction or reflux. Madersbacher et al. [9] found that radiographic (shrunken kidney or hydronephrosis) or functional (increased serum creatinine greater than 150 μmol/L [1.7 mg/dL]) deterioration was observed in 27% of patients at minimum follow-up of 5 years after ileal conduit urinary diversion.

Local or Distant Tumor Recurrence

Cancer recurrence remains a major concern after cystectomy and urinary diversion in patients with bladder cancer. Tumor recurrence may present as local recurrence in the pelvis or as distant metastasis manifested as lymphatic or remote organ spread (Fig. 12A, 12B).

Transitional cell carcinoma (TCC) of the urothelium is often multifocal. Subsequent tumors may occur anywhere in the urinary tract after treatment of the initial carcinoma. Upper tract TCC after cystectomy for muscle invasive or refractory non-muscle-invasive bladder cancer are reported to occur in 2–8% of patients [10]. Possible risk factors include the presence of TCC in the distal ureter at cystectomy [11], multifocality, association with bladder carcinoma in situ [12], locally advanced stage at surgery (stage pT3a or greater) [13], and involvement of the prostatic urethra by TCC [10]. Upper tract TCC after cystectomy is usually high grade and the prognosis is poor [10].

Although the role of routine imaging of the upper urinary tract in patients with bladder cancer is controversial, particularly for low-risk patients [10], CT urography can be useful in the detection and assessment of upper urinary tract tumors in patients who are suspected to have upper tract TCC after urinary diversion for bladder cancer. To detect upper urinary tract TCC, excretory phase CT should be included [14]. Using high-resolution images obtained with thin-section MDCT, detection of upper tract TCC may be improved. On CT, TCC of the upper urinary tract is often seen as a focal intraluminal mass (Fig. 13A, 13B), urothelial wall thickening with luminal narrowing (Fig. 14A, 14B, 14C), and infiltrating mass. However, flat or early-stage tumors may be difficult or impossible to detect at CT [15]. To evaluate TCC in the renal collecting system and ureter on excretory phase imaging in patients with bladder cancer, optimal opacification and distention are essential [14].

Late Complications Not Directly Related to Urinary Diversion

The most common late complications unrelated to neobladder reconstruction leading to open surgery were incisional hernia (1.5%) and small-bowel obstruction (1.6%) [16] (Fig. 15A, 15B).

Conclusion

MDCT can detect potential early and late complications of the urinary tract, recurrent tumors, and complications not directly related to urinary diversion. CT has an important role to identify tumor recurrence and correctable causes of urinary complications early to prevent deterioration in renal function.

View larger version: