eMedicine Specialties > Urology > Hydronephrosis and Ureter Disorders

Ureterocele: Workup

Author: Eugene Minevich, MD, Assistant Professor, Department of Surgery, Division of Pediatric Urology, University of Cincinnati
Coauthor(s): Leslie Tackett, MD, Fellow, Departments of Surgery and Pediatrics, Division of Pediatric Urology, Children's Hospital Medical Center at Cincinnati
Contributor Information and Disclosures

Updated: Jan 27, 2008

Workup

Laboratory Studies

• Urinalysis: In any child with an unexplained fever or suspicion of a UTI, a urinalysis with urine culture is indicated. Presence of pyuria, leukocyte esterase, and nitrites suggests a UTI.
• Urine culture is obtained to identify the offending pathogen and to assess for appropriate antibiotic susceptibility.
• Complete blood cell count is obtained to determine the degree of systemic infection that may be present, as well as to ascertain responsiveness to antibiotic therapy.
• Serum chemistries, especially BUN and serum creatinine, are obtained to determine baseline information and to assess the degree of renal function.
• Blood cultures are obtained in the setting of fever or urosepsis.
• Fungal cultures are obtained in infants who have been on long-term antibiotic therapy or in immunocompromised patients with clinical evidence of UTI.

Imaging Studies

• Renal or bladder ultrasonography
  • Renal and bladder ultrasonography is the first-line imaging study for evaluating the upper and lower urinary tract in the pediatric population.
  • A ureterocele is seen as a fluid-filled cystic intravesical mass. It is also known as a "cyst within a cyst."
  • Hydroureteronephrosis is noted as a dilatation of renal pelvis and the proximal ureter.
  • Renal duplication can be assessed easily with renal ultrasonography.
  • Renal ultrasonography also provides information on the thickness of renal cortex and echogenicity of renal parenchyma. The degree of echogenicity is indirectly proportional to the degree of renal dysplasia that is present.
  • Bladder ultrasonography documents the efficiency of bladder emptying by noting the amount of postvoid residual urine that is present.
• Voiding cystourethrography
  • Voiding cystourethrography (VCUG) is essential to evaluate the lower urinary tract for a ureterocele, urethral diverticulum, posterior urethral valve (PUV), ectopic ureter, and vesicoureteral reflux.
  • Ureterocele appears as a smooth, round filling defect along the base of the bladder.
  • Urethral diverticulum appears as an outpouching of the urethra. A urethral diverticulum may also represent an everting ureterocele.
  • VCUG can be used to document the efficiency of bladder emptying with assessment of the amount of postvoid residual urine that is present.
  • Posterior urethral valves are included in the differential diagnoses of antenatal hydronephrosis. On VCUG, they are characterized by visualization of the valve leaflets, dilatation and elongation of the posterior urethra, and bladder neck hypertrophy.
  • Vesicoureteral reflux of the ipsilateral lower pole ureters approaches 50%, whereas only 25% of the contralateral renal units have vesicoureteral reflux. Vesicoureteral reflux into the ureterocele is rare, but it may occur following spontaneous ureterocele rupture or after unroofing of the ureterocele.
• Diuretic nuclear renography (nuclear renal scan)
  • Nuclear renal scan using technetium 99m diethylenetriaminepentaacetic acid (DTPA) is an excellent study for establishing the differential renal function objectively and the efficiency of drainage of the dilated collecting system (washout times). DTPA is cleared almost exclusively by glomerular filtration. Its rate of clearance provides an excellent estimate of glomerular filtration rate (GFR).
  • Alternatively, technetium 99m mercaptoacetyltriglycine (MAG3) may be used. This radioisotope is rapidly cleared by tubular secretion and is not retained by the kidneys. MAG3 is an excellent replacement for DTPA (eg, diuretic renography) in the pediatric population.
• Intravenous pyelography
  • Intravenous pyelography (IVP) is useful for delineating renal anatomy and providing a subjective estimation of relative renal function. The following may be seen on IVP:
    • Hydronephrosis, revealing dilatation of collecting system
    • Hydronephrotic upper pole displacing the lower pole moiety laterally and inferiorly (ie, the "drooping lily")
    • Ureteral displacement by the hydroureter or hydronephrotic upper pole moiety
    • Cobra-head extension of the distal ureter (ureterocele) (seen in adults)
  • The diagnosis of an adult ureterocele primarily is radiologic and is based on IVP and endoscopy (urethrocystoscopy) studies.
• Magnetic resonance imaging: MRI is an excellent anatomical study for evaluating rare cases with suspected dysplastic, nonfunctioning, ectopic renal moieties and ectopic ureteral insertion.
• CT scanning of the abdomen and pelvis: If renal ultrasonography and IVP findings are equivocal, CT scanning may provide additional clues for diagnosing simple or ectopic ureterocele. CT scanning can reveal the presence of a duplicated collecting system, hydronephrotic upper pole segment, or dysplastic upper pole moiety. Although CT scanning is an excellent screening tool to detect ureteral calculi, abnormal ureteral anatomy and ureteral dilatation are better imaged with MRI.

Other Tests

• Pressure-perfusion study (Whitaker test)  
  • The Whitaker test is an invasive test, which requires percutaneous renal access to measure differential pressures between the renal pelvis and the bladder. In children, general anesthesia may be required. This procedure is used only when other methods for determining obstruction produced equivocal results and the clinical suspicion of obstruction remains high.
  • The test may be useful in evaluating equivocal urinary tract obstruction. It may be used if results of the diuretic renal scan (DTPA) are uncertain.
  • Briefly, after percutaneous renal access is achieved and a urethral catheter is placed, the renal pelvis is perfused at a constant rate. Renal pelvic pressures are then compared to bladder pressures. If the maximum renal relative pressure (renal pelvic pressure minus bladder pressure) is below 12-15 cm H₂ O, the system is considered nonobstructed. If the renal relative pressure is above 20-22 cm H₂ O, obstruction is thought to be present. Renal relative pressures between 15 and 20 cm H₂ O are equivocal. Interpretation of the Whitaker test may be complicated by anatomic issues such as persistent hydronephrosis following prior decompression of the system (relief of obstruction in posterior urethral valves) and technical issues such as determination of the appropriate perfusion flow rate.

Diagnostic Procedures

• Cystoscopy, vaginoscopy, or retrograde pyelography
  • These are endoscopic procedures that allow direct inspection and examination of the lower urinary tract, as well as the female genitalia.
  • For optimal demonstration of a ureterocele, one must examine the bladder when it is both full and empty.
  • When radiologic suspicion of a ureterocele in an adult is aroused, cystoscopy often confirms radiographic findings.
  • If clinically indicated, the ureterocele may be treated with endoscopic incision or unroofing at the same setting.

Histologic Findings

Usually, the walls of ureteroceles demonstrate loss of muscle and collagen. It appears that incomplete muscularization of the distal ureter may be responsible for expansion of the ureterocele out of proportion to the rest of the normal ureter. However, the walls of stenotic ureteroceles appear to have greater muscle composition than other types of ureteroceles.

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