What Causes Hydronephrosis and How Is It Treated?
Hydronephrosis, a condition characterized by the swelling of one or both kidneys due to a build-up of urine, typically occurs when there's a blockage in the urinary tract that prevents normal urine flow. This accumulation can lead to increased pressure within the kidney, potentially impairing its function if left untreated. Understanding the underlying causes and available treatment options is essential for effective management and long-term kidney health.
Common Causes of Urinary Obstruction Leading to Hydronephrosis
One of the most frequent causes of hydronephrosis is ureteral obstruction, often triggered by kidney stones. When a stone becomes lodged in the ureter—the tube connecting the kidney to the bladder—it prevents urine from draining properly, resulting in kidney swelling. These obstructions can be sudden and painful, requiring prompt medical attention.
Congenital and Structural Abnormalities
In some individuals, hydronephrosis stems from congenital issues, such as a narrow junction between the renal pelvis and the ureter (known as ureteropelvic junction obstruction). This narrowing restricts urine outflow from the kidney, especially in infants and young children, though it may also manifest later in life. Additionally, acquired ureteral strictures, particularly in the distal (lower) portion of the ureter, can impede urine passage and contribute to fluid buildup.
External Compression and Pelvic Conditions
External pressure on the ureters can also lead to hydronephrosis. For example, abdominal or pelvic masses, including tumors or enlarged lymph nodes, may compress the ureters and disrupt normal drainage. In women, conditions like large uterine fibroids or ovarian cysts can exert similar pressure, increasing the risk of kidney swelling.
Bladder-Related Factors Contributing to Kidney Dilation
Problems originating in the bladder can have downstream effects on the kidneys. Benign prostatic hyperplasia (BPH), a common condition in older men, causes the prostate gland to enlarge and obstruct the urethra. This leads to incomplete bladder emptying, increased residual urine, and elevated bladder pressure, which may trigger vesicoureteral reflux—a backward flow of urine into the kidneys—ultimately causing bilateral hydronephrosis.
Other bladder disorders, such as chronic cystitis (including adenocystitis) or bladder tuberculosis, can impair bladder compliance and contractility. These inflammatory conditions reduce the bladder's ability to expel urine efficiently, indirectly contributing to upper urinary tract dilation and potential kidney damage over time.
Treatment Approaches Based on Underlying Causes
Effective treatment of hydronephrosis depends heavily on identifying and addressing the root cause. In cases of acute bilateral obstruction—where both kidneys are affected—immediate intervention is crucial to preserve renal function. Procedures such as ureteral stenting or percutaneous nephrostomy (inserting a tube directly into the kidney to drain urine) are commonly performed to relieve pressure and restore urine flow.
Managing Stone-Induced Obstruction
When kidney stones are responsible, minimally invasive techniques like ureteroscopy or percutaneous nephrolithotomy (PCNL) are used to remove or fragment the stones. These procedures not only alleviate the blockage but also help prevent recurrent episodes of hydronephrosis.
Addressing Prostate and Bladder Dysfunction
In patients with BPH-related reflux, initial management often involves placing a Foley catheter to decompress the bladder and allow proper drainage. Once the acute phase resolves, further evaluation determines whether surgical options—such as transurethral resection of the prostate (TURP)—are appropriate to restore normal urinary flow.
For those with chronic bladder conditions, long-term strategies may include medication, bladder training, or surgical reconstruction, depending on the severity and impact on kidney function.
Early diagnosis and personalized treatment plans play a vital role in preventing complications such as kidney failure, infection, or permanent structural damage. If symptoms like flank pain, reduced urine output, or recurrent urinary tract infections occur, seeking prompt urological evaluation is strongly recommended.