From the Guidelines
Bilateral dilation of the renal pelvis, known as hydronephrosis, is most commonly caused by obstruction of urine flow, which can be due to various factors such as kidney stones, blood clots, tumors, or strictures in the urinary tract, as well as pregnancy, vesicoureteral reflux, neurogenic bladder dysfunction, and certain medications 1.
Causes of Hydronephrosis
The causes of hydronephrosis can be classified into several categories, including:
- Obstructive causes, such as kidney stones, blood clots, tumors, or strictures in the urinary tract 1
- Non-obstructive causes, such as pregnancy, vesicoureteral reflux, and neurogenic bladder dysfunction 1
- Medications, such as anticholinergics, that can reduce bladder contractility and contribute to hydronephrosis 1
- Congenital abnormalities of the urinary tract, which can result in bilateral renal pelvis dilation 1
Diagnosis and Treatment
Prompt diagnosis and treatment of the underlying cause of hydronephrosis are essential to prevent permanent renal damage and impairment of renal function 1.
Key Points
- Hydronephrosis can be unilateral or bilateral, and its diagnosis and treatment depend on the underlying cause 1
- Ultrasound (US) has a high sensitivity for detecting hydronephrosis and bladder distension, and can be used to guide intervention such as Foley catheter placement or nephrostomy/stenting 1
- CT urography (CTU) is an imaging study that can be used to evaluate the upper and lower urinary tracts, and can help to identify the underlying cause of hydronephrosis 1
From the Research
Causes of Bilateral Dilation of the Renal Pelvis
- Bilateral dilation of the renal pelvis can be caused by various factors, including obstructive uropathy, which can be due to calculous or noncalculous causes 2
- Noncalculous causes of obstruction include ureteral stricture, bladder or ureteral tumors, extraurinary collection, and retroperitoneal fibrosis 2
- In some cases, bilateral dilation of the renal pelvis may not be present, even in the presence of obstructive uropathy, especially in cases of malignant diseases encasing the distal parts of the ureters, retroperitoneal fibrosis, urinary calculi, and urinary infections 3, 4
- Congenital anomalies of the urinary tract can also cause urinary tract dilation, which can lead to renal failure if not treated properly 5
- The diagnosis of the cause of bilateral dilation of the renal pelvis can be made using various imaging modalities, including noncontrast computerized tomography (NCCT), magnetic resonance urography (MRU), and combined abdominal radiography (KUB) and ultrasonography (US) 2
Diagnostic Approaches
- NCCT has superior diagnostic accuracy for detecting calculous causes of obstruction, while MRU is superior for identifying noncalculous lesions 2
- Ultrasonography can be used to evaluate the presence and severity of renal pelvic dilation, but may not always be accurate in diagnosing the underlying cause 3, 4
- A combination of imaging modalities and clinical evaluation is often necessary to determine the cause of bilateral dilation of the renal pelvis and to guide management 2, 5