Renal pelviectasis is the dilation, or swelling, of the renal pelvis, the central collecting area within the kidney. This finding is often discovered incidentally during imaging tests performed for other reasons. Pelviectasis signifies that urine is accumulating and causing pressure inside the kidney. In adults, this condition frequently points to an underlying obstruction in the urinary tract that needs evaluation. Prompt diagnosis and management are necessary to prevent potential long-term damage to kidney function.
Defining Renal Pelviectasis
The kidney filters waste and produces urine, which drains through an internal system. The renal pelvis is a funnel-shaped structure in the center of the kidney that collects urine before it passes into the ureter, the tube leading to the bladder. In pelviectasis, impaired urine flow causes the pelvis to distend due to backup and increased pressure.
This dilation is a physical response to accumulating fluid. When the dilation is confined mostly to the renal pelvis, it is termed pelviectasis, often considered the mildest form. If pressure increases further, the dilation can extend into the calyces—the cup-like structures feeding into the pelvis—a condition called hydronephrosis. Healthcare providers classify the degree of dilation as mild (e.g., 5 to 9 millimeters), moderate, or severe, which guides further investigation and intervention.
Primary Causes in Adult Patients
The most frequent reason for renal pelviectasis in adults is a physical blockage along the urinary tract that impedes urine flow. Kidney stones (nephrolithiasis) are a common culprit, as a stone migrating down the ureter can obstruct the path. The stone’s location determines the severity of the obstruction and the degree of dilation.
Another cause involves the formation of scar tissue, known as a ureteral stricture, which narrows the ureter and restricts flow. These strictures can develop following previous surgeries, infections, or trauma. External compression is also a factor, where surrounding masses like tumors, cysts, or uterine fibroids press directly on the ureter.
Obstruction can also originate lower in the urinary system, such as in the bladder or prostate. For example, in men, an enlarged prostate (Benign Prostatic Hyperplasia or BPH) can block the bladder outlet, creating back pressure that travels up to the kidneys. Less commonly, pelviectasis may stem from a congenital issue, such as Ureteropelvic Junction Obstruction (UPJO), an inherent narrowing where the renal pelvis meets the ureter that may only become symptomatic later in life.
Recognizing the Signs and Symptoms
The experience of pelviectasis varies widely, depending on the severity and speed of the obstruction. In many mild cases, patients remain asymptomatic, and dilation is only discovered incidentally during imaging for an unrelated reason. When symptoms occur, they are typically related to pressure buildup or the underlying cause of the obstruction.
A common presentation is flank or back pain, often described as renal colic, which can be severe and episodic. Other urinary changes may include blood in the urine (hematuria), or increased frequency and urgency. If the obstruction leads to a urinary tract infection, systemic symptoms such as fever, chills, and nausea may develop, signaling an urgent medical situation.
Diagnostic Procedures and Treatment Approaches
Diagnosis begins with a medical history and initial screening tests. Blood work checks kidney function using measurements like serum creatinine. A urinalysis looks for signs of infection, red blood cells, or crystals that might indicate kidney stones. Imaging studies are the primary tool for confirming dilation and identifying the source of the blockage.
The initial and most common imaging modality is a renal ultrasound, which non-invasively visualizes the kidney and measures the degree of renal pelvis dilation. If obstruction is suspected, a Computed Tomography (CT) scan provides detailed anatomical information, particularly to locate stones or masses. For complex cases, specialized tests may be used to map the entire urinary tract and pinpoint the exact location of the obstruction.
Treatment for pelviectasis is directly tied to its underlying cause and severity. For mild, asymptomatic cases, management is often conservative, involving observation and regular follow-up ultrasounds. If a kidney stone is the cause, treatment options include lithotripsy (using shock waves to break the stone) or ureteroscopy (using a scope to remove the stone).
Relieving Obstruction
For conditions causing significant obstruction or kidney damage, immediate pressure relief is necessary. This is often achieved by placing a ureteral stent, a small tube inserted into the ureter to bypass the blockage. Alternatively, a percutaneous nephrostomy tube can be placed through the skin directly into the kidney to drain the urine externally. Surgical correction, such as pyeloplasty for UPJO or removal of an obstructing mass, is pursued when less invasive methods are insufficient to permanently resolve the issue.