Figure 15. Contrast leak at the distal ureteral anastomosis.
Figure 15. Contrast leak at the distal ureteral anastomosis.
Urinary fistulae may also occur from the calyces as a consequence of excessive dissection of polar renal arteries during transplantation (Fig 16) [34]. Late postoperative leaks are usually due to ureteral or parenchymal necrosis from rejection [32].
Figure 16. Calyceal urinary fistula.
Urine leaks may be undetectable by ultrasound when small, but present as localized fluid collections or urinary ascites as they enlarge (Fig 17). Urinomas typically manifest as cystic fluid collections in the pelvis adjacent to the ureter and separate from the bladder. They may enlarge rapidly, but generally do not have septations unless infected. Diagnosis can be established by ultrasound-guided needle aspiration which shows a high creatinine level in the fluid. Needle aspiration readily distinguishes a urinoma from postoperative hematoma or lymphocele, the latter having a creatinine level comparable to serum. The exact site of leak is best delineated by antegrade pyelography [35]. This procedure can be performed with minimal risk through a 21 or 22-gauge needle, with little or no pain since the kidney is denervated.
Figure 17. Urinoma visible on ultrasound.
The treatment of choice for small leaks in the immediate postoperative period is short-term urinary diversion with nephrostomy or ureteral stenting for one to two weeks. Surgical repair is reserved for small leaks which fail conservative therapy, and leaks which are initially large or associated with complete disruption of the ureteroneocystostomy [36]. Surgical reimplantation has a 93% technical success rate and a 2-year graft survival approaching 70%. Among patients in whom surgery is impossible or technically difficult due to scarring or adhesions, long-term diversion with nephrostomy or ureteral stenting may be a satisfactory alternative, having a success rate of 87% [37]. Disadvantages of this technique include a long mean closure time (>60 days) and a greater risk of urinary infection [37].
Only half of the 18% of patients who develop hydronephrosis are truly obstructed [38]. Ureteral edema, acute rejection and ureteral reflux may cause nonobstructive dilatation. The sonographic pattern of hydronephrosis is very useful in predicting whether functional obstruction is present. Dilatation confined to the renal pelvis alone (Fig 18) is rarely associated with obstruction except when it occurs within a month of transplantation. In this group, the risk of obstruction is approximately 33% [38].
Figure 18. Dilatation confined to the renal pelvis in the early post operative period.
Conversely, obstruction is present in over two-thirds of kidneys when dilatation involves both the pelvis and calyces (Fig 19).
Figure 19. Pelvic and calyceal dilatation is associated with obstruction in over two-thirds of cases.
Ultrasound shows the exact site of obstruction in only 13-15% of cases (Figs 20, 21, 22) - add some text here [38].
Figure 20. Hydronephrosis secondary to a ureteral stone (arrow). Dilated renal pelvis (p) and lower pole pf the transplant kidney (K) are visible. A ureteral stent is present.
Figure 21. Normal branching of the main renal vein (arrows) in the central renal sinus can be mistaken for hydronephrosis.
Figure 22. CDI readily confirms that this is a vessel.
Antegrade pyelography and the Whitaker test are complementary to ultrasound and provide valuable anatomic and physiologic information about the site and clinical significance of obstruction (Fig 23).
Figure 23. Antegrade pyelogram depicting distal ureteric stricture.
The immediate treatment of choice for obstructive hydronephrosis is decompression by percutaneous nephrostomy. Ureteral strictures can be managed by percutaneous balloon dilatation and stenting, long-term stenting alone, or open repair [10]. Percutaneous techniques have long-term success rates of 50-70% and are most effective for soft, short segment strictures [39]. Long-term success rates for surgical repair exceed 80% (Fig 24) [39].
Figure 24a. Longitudinal sonogram demonstrates transplant hydronephrosis and a lower pole stone.
Figure 24b. The nephrostogram shows a second stone in the distal ureter (lower black arrow) above a tight stricture. A second long mid ureteral stricture is present (white arrows). The upper stricture was not judged suitable for balloon dilatation due to its length. Surgical reimplantation was required.
Next: Lymphocoele
Dr C V Zwirewich
Last updated 11th August 1998