From the Guidelines
The diagnostic workup for mild hydronephrosis should begin with a renal ultrasound, as it can confirm hydronephrosis and potentially identify obstructing lesions, according to the most recent study by Whitworth et al 1. The workup for mild hydronephrosis begins with a thorough clinical assessment including a detailed history and physical examination to identify potential causes and associated symptoms. Initial laboratory tests should include:
- Urinalysis to check for infection or hematuria
- Complete blood count to assess for infection
- Comprehensive metabolic panel to evaluate renal function through blood urea nitrogen and creatinine levels Imaging studies are essential, starting with renal ultrasound which can confirm hydronephrosis and potentially identify obstructing lesions. Depending on findings, additional imaging may include:
- CT urography or MR urography to better characterize the anatomy and identify specific causes of obstruction such as stones, tumors, or strictures
- CT abdomen and pelvis without IV contrast, which can be useful in evaluating symptomatic patients when US is inconclusive, as noted by Pathan et al 1 In cases where obstruction is suspected but not clearly visualized, a diuretic renal scan (MAG-3 or DTPA) can help assess the functional impact of the obstruction. Voiding cystourethrogram may be indicated if vesicoureteral reflux is suspected, particularly in pediatric patients. Cystoscopy might be necessary if lower urinary tract obstruction is suspected. The workup should be tailored to the patient's age, sex, and clinical presentation, as hydronephrosis can result from various conditions including urinary stones, pregnancy, ureteropelvic junction obstruction, or malignancy. Close follow-up with repeat imaging is important to monitor for progression, especially if the initial workup does not identify a clear cause requiring immediate intervention, as suggested by Claudon et al 1.
From the Research
Diagnostic Workup for Mild Hydronephrosis
The diagnostic workup for mild hydronephrosis involves various imaging modalities to determine the cause and extent of the condition.
- Imaging modalities used to diagnose hydronephrosis include:
- Sonography
- Radiography
- Magnetic resonance imaging
- Nuclear medicine technology 2
- Post-voiding repeated renal ultrasonography can be useful in avoiding unnecessary further examination to determine whether upper urinary tract obstruction exists, when slight hydronephrosis is observed upon screening by simultaneous renal and urinary bladder ultrasonography for asymptomatic microhematuria 3
- Diuretic excretory urography, ultrasonography, and renal scans can be used to diagnose intermittent hydronephrosis, a difficult condition to diagnose due to the mild degree of dilatation encountered in imaging studies 4
- A diagnosis algorithm should be used to evaluate unknown hydronephrosis, and further investigation is recommended to define the precise etiology of the condition 5
Diagnostic Techniques
Diagnostic techniques for hydronephrosis include:
- Ultrasonography to evaluate the renal collecting system and detect any obstructions
- Computed tomography to evaluate the abdominal and pelvic pathology
- Magnetic resonance imaging to evaluate the urinary system and detect any abnormalities
- Nuclear medicine technology to evaluate the renal function and detect any obstructions 6, 2
Grading Scale and Treatment Options
A grading scale for hydronephrosis is presented, and treatment options are explained, including the role of various imaging specialists in the diagnosis and management of the condition 2