Early and late postsurgical complications are common.
CT is an accurate method for detecting these complications.
MDCT urography must be performed after the oral administration of water or of furosemide intravenously 15-20 minutes before the study (to increase renal excretion and urinary tract distention).
Oral contrast is administered if there is a suspicion of an intestinal leak presence.
It is important to scanning three phases:
Without contrast: to detect stones or any other calcifications.
- Nephrogenic phase at 80-100s: to characterize renal or urethral lesions,
and fluid collections.
- Excretory phase at 10 min.
A longer delay may be necessary in patients with urinary tract obstruction or delayed excretion.
The excretory phase images are useful for assessment of urinary leaks or fistulas and for the detecting and evaluating another urothelial lesions.
Early complications usually occur in the first 30 days after surgery and are frequently related with the surgical procedure performed and include:
1.
Bowel transit disorders:
- Adynamic ileus is an intestinal complication and it is the most common bowel complication,
affecting approximately 20% of patients.
On CT generalized dilatation of both small and large bowel obstruction associated with gas-fluid levels,
without an apparent cause,
can be seen.
It is resolved generally after 5 to 7 days after surgery.
- Small-bowel mechanical obstruction is frequently caused by adhesions adjacent to the anastomosis and can manifest as an early or late complication.
On CT,
small bowel proximal to the obstruction point appears dilated with gas-fluid levels.
CT findings of adhesive small-bowel obstruction may be made in the presence of an abrupt change in bowel caliber.
Intravenous contrast administration may useful in the diagnosis of bowel ischemia associated with obstruction.
2.
Urinary extravasation or anastomosis dehiscence is now an uncommon complication and arises most frequently from the uretero-ileal anastomosis.
Urinary leakage should be suspected when there is an increased in debit from any drainage catheters or urinary drainage from the abdominal surgical wound.
It is important to evaluate excretory imaging phase in order to make the correct diagnosis of contrast leakage.
3. Leakage of fecal contents from bowel leak is a rare complication of urinary diversion.
Bowel leak most often occurs in the ileal-ileal anastomosis.
Multiple factors may contribute for bowel leakage as ischemia,
previous radiotherapy,
steroid use,
inflammatory bowel disease and distal bowel obstruction.
It is imperative to detect this complication as soon as possible because peritonitis and abscess formation can occur.
4. Wound infections are easily diagnosed at physical examination and imaging in such cases has a lesser important role.
5.
Fluid collections as urinoma,
abscess,
lymphocele or hematoma are common complications in the early postoperative period and are frequently confined in the location of the excised bladder.
- Patients with an urinoma commonly present with signs of peritoneal irritation and fever but it is suspected when a leaked urine is not collected by the postoperative drainage catheters.
The time of excretory phase imaging is crucial for the diagnosis and allows the differential diagnosis from other types of postoperative fluid collections.
The contrast accumulation within the collection can be identified on excretory phase images and is diagnostic of urinoma.
Percutaneous drainage of an urinoma is usually required.
(Figure 2)
- A non-infected hematoma typical is a heterogeneous,
nonenhancing collection near the surgical area.
- Lymphoceles may be seen in patients who have performed lymphadenectomy associated with radical cystectomy.
CT shows a homogeneous water attenuation collection with a very thin wall,
in proximity to the surgical clips.
- Any of the previously collections described may become infected,
resulting in an abscess.
Abscess may sometimes be difficult to differentiate it from an uninfected collection.
A fluid collection with an enhancing thickened wall and the presence of air-bubbles inside the collection are suggestive CT findings of abscess.
(Figure 3).
6.
After urinary diversion surgery,
fistulas are usually located in the intestinal anastomosis and may be entero-urinary,
entero-genital,
or entero-cutaneous (Figure 4).
Previous pelvic radiation therapy is a predisposing risk factor. A complete medical history may be helpful for determining the suspected fistula localization.
Fistulas may resolve with conservative management if there is good drainage and there is no sepsis. Sometimes surgical intervention is required.
7. Urinary obstruction is a rare complication in the first 30 days after surgery.
When it occurs in the early postoperative period is often due to an error in surgical technique or the presence of edema at the uretero-intestinal anastomosis.
Another possible causes of obstruction are extrinsic compression as fluid collections or masses that should be excluded.
Long term complications of urinary diversion occur 1 month or more after surgery and include:
1. Tract urinary infection may appear as early or late complication.
Some of the normal urinary tract and urothelium defense mechanisms are impaired in patients with a urinary diversion who are more susceptible to bacterial infections.
Among patients with an ileal conduit,
bacteriuria was found in approximately 85%.
Ureteral obstruction,
presence of urolithiasis or urinary reflux are risk factors for pyelonephritis occurrence.
The diagnosis of pyelonephritis is commonly based on clinical and laboratory findings,
but the typical features of pyelonephritis also may be seen at CT.
2. Ureteral or ileal stenosis
Ureteral stricture is an uncommon complication of incontinent urinary diversion and it usually occurs at the uretero-ileal anastomosis.
The most common cause of ureteral stricture is ischemia of the distal ureter with consequent fibrosis.
Others causes such an improperly created anastomosis (causing early obstruction) or a recurrent tumor may be responsible for ureteral strictures.
The left distal ureter has a particularly high risk for strictures due to its increased angulation.
Uretero-enteric stricture is often suspected when there is an increase in the serum creatinine level or a progressive hydronephrosis at follow-up CT imaging examinations.
It is important to remember that some degree of hydronephrosis can be present due to urinary reflux after surgery and it is not necessarily indicative of a urinary tract obstruction.
3. Parastomal herniation and stomal stenosis
- Parastomal intestinal hernias (figure 5) are frequently seen in patients with ileal conduit reconstruction.
Obesity and advanced age may be contributing factors for development of these type of hernias.
CT is useful for detecting these hernias,
particularly in obese patients and allows the detection of associated complications such infection (figure 6).
- Stomal stenosis (figure 7) is a common late complication of the ileal conduit procedure and appears as narrowing of the distal aspect of the conduit near its outlet with the skin surface.
Stomal stenosis is best appreciated with fluoroscopic study.
This complication can lead to hydronephrosis,
renal failure and infection.
4. Lithiasis
Urinary tract calculi is a common complication of urinary diversion procedures (figure 8).
Patients who undergone urinary diversions have a higher risk of urinary calculi formation.
Calculi may be located along the urinary conduit or in the upper urinary tract.
They appear more frequently within the left ureter than the right ureter due left ureter angulation.
It is essential to detect calculi early because they may cause urinary tract obstruction and consequently affect renal function.
CT is the most sensitive imaging modality for stone detection.
Calculi may not be detectable on delayed phase CT because of the excretion of intravenous contrast,
so unenhanced CT is essential to detect calculi.
5. A tumor recurrence must be excluded.
Recurrence of urothelial neoplasm may occur locally or in the upper urinary tract (figures 9 and 10).
The incidence of tumor recurrence is related to the disease stage: patients with advanced disease stage or with nodal disease has a greater risk for recurrence.
CT is most useful for evaluating recurrent pelvic tumor,
lymph node involvement and distant metastases.
Knowledge of the expected postsurgical anatomy is essential to prevent misdiagnosis.
At CT,
local recurrence may present as a pelvic soft-tissue mass,
an obstructing ureteral stenosis,
including at the uretero-ileal anastomosis (usually associated with an enhancing soft-tissue mass) or lymphadenopathy.