What is the appropriate management for a patient presenting with renal contour distortion with prominence, potentially indicating renal tumors, obstructive uropathy, or polycystic kidney disease?

Management of Renal Contour Distortion with Prominence

The appropriate management begins with urgent cross-sectional imaging using CT urography (CTU) without and with IV contrast or renal ultrasound to differentiate between renal mass, obstructive uropathy, and polycystic kidney disease, followed by risk-stratified intervention based on the underlying etiology. 1, 2

Initial Diagnostic Approach

Immediate Clinical Assessment

• Obtain urinalysis to rule out urinary tract infection and hematuria, which is mandatory for all patients with suspected renal pathology 2
• Measure post-void residual volume in patients who can spontaneously void, particularly those with emptying symptoms, enlarged prostate, neurologic disorders, or long-standing diabetes 2
• Perform abdominal examination for distension, tenderness, or palpable masses, and conduct rectal/genitourinary examination to evaluate prostate size in men and pelvic organ prolapse in women 2
• Document symptom duration (flank pain, hematuria, polyuria) and review medications that may affect urinary tract function 2

First-Line Imaging Strategy

CTU without and with IV contrast provides the most comprehensive evaluation and should be the preferred initial imaging modality 1, 2

Alternative imaging options based on clinical context:

• CT abdomen and pelvis without IV contrast is particularly useful when obstructive urolithiasis is the primary concern 1
• Renal ultrasound can differentiate acute from chronic processes by determining renal size, cortical thickness, and presence of hydronephrosis 1
• MAG3 renal scan determines whether true obstructive uropathy is present and is the de facto standard for diagnosing renal obstruction 1

Management Based on Etiology

If Renal Mass is Identified

For solid renal masses, intervention with curative intent should be recommended when oncologic benefits outweigh treatment risks 1

• Patients with pathologically-proven benign renal masses require occasional clinical evaluation and laboratory testing for treatment sequelae but do not need routine periodic imaging 1
• Patients with treated malignant renal masses require periodic medical history, physical examination, laboratory studies (serum creatinine, eGFR, urinalysis), and imaging directed at detecting metastatic spread or local recurrence 1
• Additional laboratory evaluations (complete blood count, lactate dehydrogenase, liver function tests, alkaline phosphatase, calcium) should be obtained if advanced disease is suspected 1

If Obstructive Uropathy is Identified

Bilateral hydronephrosis or hydronephrosis in a solitary kidney requires urgent evaluation within hours, not days, as these conditions pose greater risk to overall renal function 2

• For pyonephrosis (hydronephrosis with infection), percutaneous nephrostomy (PCN) is the preferred decompression method over retrograde ureteral stenting, with technical success rates >95% for dilated systems 2
• PCN is preferred when infection is present, obstruction is at the ureterovesical junction, or extrinsic compression from malignancy is suspected 2
• Bilateral PCN tubes are required for bilateral obstruction, as each kidney must be decompressed separately 2

Common pitfall: Diuretic renography may yield false-negative results in cases of dehydration, early/acute obstruction, extrinsic compression, or intermittent obstruction 3

• MAG3 should be used over DTPA for diuretic renography as it is more efficiently extracted by the kidney, especially in patients with reduced renal function 3
• Ensure adequate hydration before and during the study to maximize test accuracy 3

If Polycystic Kidney Disease is Identified

• Blood pressure treatment goals should be less than 130/80 mm Hg 4
• Treatment should include angiotensin-converting enzyme inhibitors 4
• Patients diagnosed before age 30 have worse renal survival and require more aggressive monitoring 4
• Polycystic kidney disease is the fourth most common cause of end-stage renal disease 4

Advanced Testing Considerations

• Urodynamic studies should not be routinely performed in initial evaluation but may be indicated when diagnostic uncertainty exists, especially with mixed incontinence, obstructive voiding symptoms, elevated post-void residual, or possible neurogenic lower urinary tract dysfunction 2
• Cystoscopy is not routinely needed but is diagnostically helpful in patients with hematuria, history of recurrent UTI, obstructive voiding symptoms, or women with overactive bladder symptoms and history of prior sling for stress urinary incontinence 2

Critical Management Principles

Avoid nephrotoxic medications in patients with acute kidney injury and provide urgent hemodialysis for severe AKI with hyperkalemia 2

• In cases of malignant obstruction, PCN has been shown to improve renal function and survival, but careful patient selection is critical 2
• Correlate findings with multiple imaging modalities (ultrasound, CT urography, or MR urography) to improve diagnostic accuracy when initial imaging is equivocal 3