Ureteral Stricture Workup

• Important laboratory studies in ureteral strictures include the following:

  • Urinalysis
  • Urine culture and sensitivities
  • Serum electrolytes with serum blood urea nitrogen and creatinine

• Renal ultrasonography

  • Renal ultrasonography is often the initial imaging study performed to evaluate for ureteral strictures because the findings are highly sensitive for hydronephrosis, the study is noninvasive, and the evaluation requires no intravenous contrast.
  • Limitations of ultrasonography include fairly poor ureteral imaging, especially in patients who are obese, and the fact that this study is anatomic rather than functional.
• Computed tomography

  • Noncontrast helical computed tomography (NCCT) is now commonly used to evaluate patients with acute flank pain and is therefore often performed in patients with a history of calculus disease.
  • NCCT findings are highly sensitive and specific for helping reliably identify hydroureteronephrosis and the site of dilatation. In addition, ureteral wall thickness, imbedded or extruded calculi, and urinary extravasation can be appreciated.
  • Secondary signs of obstruction (eg, periureteral stranding) can also be appreciated and do not require intravenous contrast for detection; however, NCCT is not a functional study and cannot be used to reliably estimate the degree of obstruction or relative renal function.
  • The addition of intravenous contrast to the CT scan allows assessment of the degree of obstruction, and a delayed nephrogram is often present. Delayed views provide important information regarding anatomic relationship of the strictured ureter to the adjacent structures. Contrast use must be counterbalanced by the nephrotoxicity of the contrast and the risk of adverse contrast reaction. Contrast CT scanning may be the best test for evaluating extrinsic causes of obstruction and evaluating regional or metastatic disease when malignant ureteral obstruction is evaluated.
• Intravenous pyelography

  • Intravenous pyelography (IVP) was once the traditional functional imaging study of choice. Since the widespread availability of CT scanning, IVP is rarely used.
  • IVP is particularly valuable in patients who have partial obstruction with normal renal function, but this imaging study is impaired by the risks of intravenous contrast. See the images below. Ureteral stricture. Intravenous pyelogram (IVP) in a woman 4 weeks after a total abdominal hysterectomy for endometriosis. A ureteral injury was identified intraoperatively and repaired by the gynecologist. The IVP image reveals a high-grade right distal ureteral stricture. Ureteral stricture. The same patient as in the image above, after a combined antegrade and retrograde endoureterotomy of the completely obliterated stricture with holmium:YAG laser, subsequent dilation to 15F with a ureteral dilating balloon, and stenting with a double-J ureteral stent. The image is an antegrade nephrostogram prior to removal of the nephrostomy tube. The patient is asymptomatic and stent-free without obstruction 3 months after the procedure.
• Retrograde pyelography

  • This study very useful because it yields excellent ureteral-mucosal detail in the absence of intravenous contrast and is often used in preparation for endoscopic or open surgery to repair a ureteral stricture.
  • Limitations include relative invasiveness and a requirement for cystoscopy. See the image below.Ureteral stricture. This right retrograde pyelogram reveals a tight right midureteral stricture in a man 3 years after an aortobifemoral bypass for obstructive peripheral vascular disease. The man presented with azotemia and bilateral hydroureteronephrosis to the mid ureters. Bilateral stents were placed, and subsequent bilateral ureterolysis with omental wrapping was performed. Both ureters were encased in a dense inflammatory process anterior to the vascular graft.
• Nuclear medicine diuretic scan

  • This the most widely used test to measure the degree of obstruction and to quantify relative renal function.
  • The diuretic renal scan is used to measure clearance of the radiopharmaceutical over time and to calculate renal blood flow, which correlates with relative renal function.
  • The most common radiopharmaceuticals currently used to evaluate relative function and obstruction include technetium Tc 99m mercaptoacetyltriglycine, which is primarily a tubular agent, and technetium Tc 99m diethylenetriamine pentaacetic acid, which is primarily a glomerular agent.
  • At the peak uptake of the radiopharmaceutical, intravenous furosemide, usually 20 mg, may be administered to induce diuresis and to allow the assessment of urinary clearance.
  • Relative disadvantages of nuclear medicine diuretic scans include its qualitative nature, user dependence, and lack of informative anatomic data.
• Intraluminal ultrasonography^[7]

  • According to some authors, this is useful to help evaluate ureteral obstruction.
  • Advantages include the ability to assess ureteral submucosal and periureteral abnormalities (eg, fibrosis, vascular structures).
  • Disadvantages include an invasive nature and an inability to assess complete or near-complete obstruction.
• Magnetic resonance imaging: MRI may be useful for evaluating patients with a renal transplant who have renal failure and in whom ultrasonographic findings are normal or equivocal.

Histologic findings of benign ureteral strictures are nonspecific. Scar formation with collagen deposition and inflammatory infiltrate may be prominent. Radiation strictures may demonstrate a lack of cellularity and vascular hypertrophy with acellular matrix. Malignant strictures have characteristics of the specific carcinoma pathology, most commonly TCC.

Strictures may be staged based on location and severity. Location is divided into proximal (UPJ to sacrum), mid (over sacrum), and distal (inlet of pelvis to UVJ). Severity commonly refers to the patient's degree of obstruction (ie, mild, moderate, severe).