Obstructive uropathy is a condition where a blockage prevents urine from draining properly through the urinary tract. This interruption can occur at any point from the kidneys to the urethra. The backup of urine causes pressure and swelling in the kidneys, a condition known as hydronephrosis, which can affect one or both. If left unaddressed, this persistent pressure can lead to kidney damage.
Causes of Urinary Obstruction
The reasons for urinary obstruction are diverse and can be categorized as structural, congenital, or acquired. Structural issues include physical impediments like kidney stones, which are hard mineral deposits that can lodge in the ureters or urethra. In men, a common cause is benign prostatic hyperplasia (BPH), a noncancerous enlargement of the prostate gland that can squeeze the urethra. Tumors located within or near the urinary tract can also press on and obstruct these passages.
In women, pelvic organ prolapse, where organs descend and press on the bladder or urethra, can lead to a blockage. Some individuals are born with congenital abnormalities that cause obstruction, such as a ureteropelvic junction (UPJ) obstruction, a blockage where the ureter connects to the kidney.
Acquired problems can also lead to blockages. Scar tissue, known as a stricture, can form in the ureter or urethra, narrowing the passage as a result of previous surgeries, infections, or injuries. Radiation therapy in the pelvic area can also cause strictures to develop.
Recognizing the Symptoms
The signs of a urinary blockage differ if the obstruction develops suddenly (acute) or gradually (chronic). An acute obstruction often presents with severe symptoms, including intense pain in the flank (the side of the body between the ribs and hip) or lower abdomen. This pain can be accompanied by nausea, vomiting, and a complete inability to urinate despite a strong urge.
In contrast, chronic obstruction may have subtle symptoms that are easily overlooked. These include a weak or dribbling urine stream, a feeling that the bladder is not completely empty, and the need to urinate more frequently, especially at night. Recurrent urinary tract infections (UTIs) can also be a sign of an underlying blockage, as stagnant urine creates a breeding ground for bacteria.
If the obstruction persists and affects kidney function, other symptoms may appear. Swelling in the legs or feet can occur as the kidneys lose their ability to regulate fluid balance. The presence of blood in the urine is another indicator that warrants medical attention.
The Diagnostic Process
Identifying the location and cause of a urinary blockage begins with a physical examination and a discussion of symptoms and medical history. Based on this assessment, a doctor will order laboratory tests to evaluate the urinary system’s function.
Blood tests are used to measure levels of substances like creatinine and blood urea nitrogen (BUN). Elevated levels of these waste products in the blood can indicate that the kidneys are not filtering effectively. A urinalysis examines a urine sample and can reveal blood, white blood cells, or bacteria, suggesting infection or inflammation.
Imaging studies are used to confirm the diagnosis and pinpoint the source of the blockage. An ultrasound is often the first test performed because it is non-invasive and can visualize the kidneys and bladder. It can detect the swelling caused by urine backup and may identify the obstruction. For a more detailed view, a computed tomography (CT) scan provides cross-sectional images of the urinary tract, allowing doctors to identify the precise nature of the blockage.
Treatment Approaches
The management of obstructive uropathy focuses on two primary goals: draining the backed-up urine and addressing the underlying cause. The initial step is to decompress the urinary system to prevent further kidney damage. A urethral catheter, a thin tube inserted through the urethra into the bladder, is a common method for draining urine when the blockage is in the lower urinary tract.
If the blockage is higher up in the ureters, a ureteral stent may be placed. A stent is a small, flexible tube inserted into the ureter to hold it open and allow urine to bypass the obstruction. In situations where a stent cannot be placed or the obstruction is near the kidney, a nephrostomy tube may be used. This involves inserting a tube directly into the kidney through the skin on the back to drain urine externally into a collection bag.
Once the immediate pressure has been relieved, treatment shifts to resolving the root cause of the obstruction. The specific approach depends on the diagnosis. Kidney stones may be broken up with sound waves in a procedure called lithotripsy or removed surgically. An enlarged prostate (BPH) might be treated with medications to shrink the gland or with surgical procedures to remove excess tissue. If the cause is a tumor, treatment could involve surgery, while strictures may require surgical repair to widen the narrowed passage.