The renal pelvis is a funnel-shaped structure in the center of each kidney that collects urine before it travels to the bladder. Pelviectasis refers to the abnormal dilation or swelling of this renal pelvis due to a backup of urine. While often monitored in infants, its discovery in an adult signals a significant underlying issue requiring prompt attention. This fluid backup creates pressure that can ultimately impair kidney function, making it important to understand the cause and management of this adult presentation.
Defining Renal Pelviectasis
The urinary system is designed for one-way flow, moving urine from the kidney into the renal pelvis and then through the ureter to the bladder. When a blockage occurs, urine cannot drain properly, causing it to pool and create pressure within the kidney. This pooling results in the characteristic ballooning of the renal pelvis, defining pelviectasis.
Pelviectasis is often considered a milder form of dilation, confined primarily to the renal pelvis itself. It exists on a spectrum with hydronephrosis, a more severe condition where dilation involves both the renal pelvis and the calyces. Both conditions stem from the same fundamental problem: impaired urine outflow causing internal pressure and swelling. The extent of the dilation guides the urgency of diagnosis and intervention.
Common Causes of Obstruction in Adults
The primary reason for pelviectasis in adults is a physical or functional obstruction that impedes urine flow, categorized as intrinsic (within the urinary tract) or extrinsic (compression outside the tract).
Intrinsic Obstruction
The most frequent intrinsic cause is kidney stones (urolithiasis), especially when a stone lodges in the ureter. This can completely block the passage, leading to a rapid buildup of pressure in the renal pelvis. Another intrinsic cause involves strictures, which are areas of abnormal narrowing within the ureter resulting from prior inflammation, surgery, or congenital issues.
Extrinsic Compression
Extrinsic compression occurs when masses or structures outside the urinary tract press upon the ureter or bladder neck. Tumors are a major concern, including cancers of the kidney, bladder, prostate, or larger abdominal and pelvic masses like ovarian or colorectal tumors. These growths physically squeeze the ureter, restricting urine flow.
In men, Benign Prostatic Hyperplasia (BPH), or an enlarged prostate, is a common cause, particularly in older age groups. As the prostate grows, it compresses the urethra where it exits the bladder, transmitting pressure backward into the renal pelvis. Less commonly, functional issues like vesicoureteral reflux (VUR), where urine flows backward from the bladder toward the kidney, can also contribute to dilation.
Recognising Symptoms and Diagnostic Methods
The clinical presentation of pelviectasis in adults varies widely, ranging from entirely asymptomatic to causing debilitating pain. In chronic cases where obstruction develops slowly, the condition may be discovered incidentally during imaging for an unrelated issue.
Symptoms typically relate to the suddenness and severity of the pressure buildup. The classic symptom is renal colic, a severe, intermittent flank pain that often radiates to the abdomen or groin, commonly associated with a passing kidney stone. Accompanying symptoms include nausea, vomiting, and hematuria (blood in the urine). If the trapped urine becomes infected, patients may develop fever, chills, and painful urination, indicating pyelonephritis.
Diagnostic Imaging
Diagnosis is primarily established through medical imaging, starting with a renal ultrasound. Ultrasound allows the clinician to visualize the kidney and measure the degree of dilation in the renal pelvis, which is often graded from mild to severe. If obstruction is suspected, a Computed Tomography (CT) scan is frequently used to identify the precise location and nature of the cause, such as a kidney stone or a tumor.
To assess kidney function, especially when standard imaging is unclear, a nuclear renal scan (diuretic renography) may be performed. This test uses a radioactive tracer and a diuretic to evaluate how quickly the kidney clears the tracer. This helps differentiate between non-obstructive dilation and a true functional obstruction requiring intervention.
Treatment Strategies and Prognosis
Treatment for adult pelviectasis depends entirely upon identifying and resolving the underlying cause of the obstruction. When severe obstruction or infection is present, immediate acute management is necessary to relieve pressure and protect the kidney. This often involves temporarily diverting urine flow by placing a ureteral stent to bypass the obstruction, or by performing a percutaneous nephrostomy to drain the urine externally.
Once the acute crisis is managed, definitive treatment targets the source of the blockage. For kidney stones, options range from observation to non-invasive procedures like shock wave lithotripsy, or surgical removal via ureteroscopy. If a tumor is the cause, treatment involves surgical excision, chemotherapy, or radiation therapy, depending on the cancer’s type and stage.
An enlarged prostate may be managed with medication to shrink the gland or relax the bladder neck, or with minimally invasive surgical procedures. Prompt intervention is important because chronic, unaddressed obstruction can lead to permanent kidney damage, known as obstructive nephropathy. If the cause is quickly removed, the affected kidney often recovers function fully, but a delay can result in irreversible loss of filtration capacity.