Hydronephrosis is a condition where one or both kidneys become swollen due to a buildup of urine. This swelling occurs because urine outflow is obstructed along the urinary tract, or because of urine flowing backward toward the kidney (reflux). Common causes of this backup include kidney stones, tumors, scar tissue, or congenital abnormalities. Treatment is specialized and depends entirely on identifying and managing the underlying cause that puts pressure on the kidney’s ability to filter waste.
Initial Assessment and Diagnostic Steps
Initial identification often begins with a visit to a primary care doctor or an emergency room due to symptoms like flank pain, nausea, or changes in urination. Initial laboratory work establishes the patient’s overall kidney status and checks for infection. Blood tests measure serum creatinine and blood urea nitrogen (BUN) to assess kidney filtering function.
A urinalysis is standard and can detect blood, bacteria, or crystals that may indicate a kidney stone or infection. The primary diagnostic tool is the renal ultrasound, which visualizes the kidney’s size and swelling. More detailed imaging, such as a computed tomography (CT) urogram or magnetic resonance imaging (MRI), may be ordered to pinpoint the exact location and nature of the obstruction. For precise function measurement, a nuclear medicine scan (e.g., MAG-3 scan) assesses the drainage rate and the contribution of each kidney.
Defining the Adult Hydronephrosis Treatment Team
The two principal specialists involved in adult hydronephrosis care are the urologist and the nephrologist, and their roles are distinct. The urologist is a surgical specialist who focuses on the physical, structural, and obstructive causes of the condition. They address blockages caused by kidney stones, tumors, strictures, or an enlarged prostate. The urologist performs procedures necessary to restore normal urine flow and relieve pressure on the kidney.
The nephrologist, in contrast, is a medical specialist focusing on the function and overall health of the kidneys. They manage the medical consequences of hydronephrosis, such as reduced kidney function, high blood pressure, or electrolyte imbalances. A nephrologist becomes the primary consultant if the cause is non-obstructive, such as systemic diseases, or if the patient develops acute or chronic kidney injury. In complex cases, both specialists work together: the urologist addresses the physical obstruction, and the nephrologist manages the kidney’s medical health.
Specialized Care for Pediatric Cases
Care for hydronephrosis in infants and children is managed by the pediatric urologist and the pediatric nephrologist. Hydronephrosis in this population is often detected before birth during routine prenatal ultrasounds, termed antenatal hydronephrosis. Common causes are congenital, such as Ureteropelvic Junction (UPJ) obstruction or Vesicoureteral Reflux (VUR).
The pediatric urologist is the surgical expert who manages these structural abnormalities. They perform reconstructive procedures like a pyeloplasty to correct a UPJ obstruction. The pediatric nephrologist focuses on non-surgical management, including monitoring kidney function, managing blood pressure, and prescribing prophylactic antibiotics to prevent urinary tract infections. For mild to moderate cases, “watchful waiting” is frequently adopted, as many congenital forms of hydronephrosis spontaneously improve or resolve as the child grows.
Treatment Modalities and Long-Term Monitoring
Treatment for hydronephrosis aims to relieve the obstruction and preserve kidney function. For acute blockage, urologists may perform a minimally invasive procedure to place a ureteral stent, which bypasses the blockage and allows urine to flow from the kidney to the bladder. Alternatively, a percutaneous nephrostomy tube may be inserted through the skin directly into the kidney’s collecting system to drain urine externally, often done for infected or highly severe obstructions.
If a kidney stone is the underlying problem, procedures like lithotripsy may be used to break the stone into smaller fragments. For permanent obstructions, a surgical repair, such as a pyeloplasty for UPJ obstruction, removes the narrowed section and re-connects the healthy parts of the urinary system. Following any intervention, long-term monitoring is necessary and involves serial imaging studies like ultrasound to check for recurrence of swelling and regular blood work to ensure kidney function is stable.