Hydroureteronephrosis: Causes, Diagnosis and Treatment

Hydroureteronephrosis is the widening of the ureter and kidney drainage system when urine cannot flow normally to the bladder. Procedures are chosen to drain urine and treat the cause; recovery and long-term results depend mainly on how quickly the obstruction is relieved and whether kidney damage or infection is present.

Hydroureteronephrosis: what it means

Hydroureteronephrosis occurs when urine backs up above a blockage or functional problem in the urinary tract. The ureter, the tube carrying urine from the kidney to the bladder, becomes widened (hydroureter), and the kidney’s collecting system also expands (hydronephrosis). It may affect one side or, less commonly, both sides.

This finding is usually identified on an ultrasound or CT scan. It does not automatically mean permanent kidney damage, but prolonged pressure within the kidney can reduce its ability to filter waste. The priority is to determine where the urine flow is impaired, whether infection is present, and how urgently drainage is needed.

Symptoms can be mild or absent when swelling develops gradually. In other situations, especially with a sudden stone blockage, pain can be intense. Care is individualized because the best approach depends on the cause, severity, symptoms, kidney function, and overall health.

Symptoms and possible complications

Symptoms vary widely. A sudden obstruction may cause sharp pain in the side or back, often called flank pain, that can move toward the lower abdomen or groin. Nausea, vomiting, urinary urgency, burning during urination, cloudy urine, or blood in the urine can also occur.

Gradual obstruction may cause few symptoms and may first be detected through imaging, recurrent urinary infections, or changes in kidney blood tests. In children, it may be discovered before birth or during evaluation for urinary tract infections or poor growth.

An obstructed urinary tract can allow bacteria to multiply. Infection behind a blockage can become serious because infected urine may not drain properly. Untreated or recurrent obstruction may also lead to loss of kidney function, particularly if both kidneys are affected or a person has only one functioning kidney.

• Flank, abdominal, or groin pain
• Fever or chills, particularly with urinary symptoms
• Nausea or vomiting
• Blood in the urine
• Reduced urine output or difficulty passing urine
• Repeated urinary tract infections

Causes and risk factors

Urinary stones are a common cause of sudden hydroureteronephrosis. A stone may lodge in the ureter and prevent urine from reaching the bladder. The condition may also result from ureteral narrowing, called a stricture, which can develop after prior surgery, inflammation, radiation treatment, injury, or repeated stone passage.

Other causes include an enlarged prostate, pelvic organ prolapse, pregnancy-related urinary tract compression, blood clots, bladder emptying problems, and masses in or near the urinary tract. Some people are born with structural differences at the junction between the kidney and ureter or where the ureter enters the bladder.

Risk factors depend on the underlying cause. A history of stones, recurrent urinary infection, urologic surgery, prostate disease, pelvic cancer treatment, or neurological conditions that affect bladder emptying may increase risk. Identifying the cause is essential because treating swelling alone without addressing the obstruction can allow it to return.

How hydroureteronephrosis is diagnosed

Assessment begins with medical history, symptoms, examination, and urine and blood tests. A urine test can look for blood, infection, or crystals, while blood tests help assess kidney function and signs of inflammation. Urine culture may be needed when infection is suspected.

Ultrasound is often the first imaging test because it can show kidney swelling without radiation. A CT scan may provide more detailed information, especially when a stone is suspected or the level of obstruction is unclear. Depending on the situation, clinicians may also use MRI, contrast imaging of the urinary tract, or a nuclear medicine scan to assess drainage and each kidney’s function.

In some cases, a urologist may examine the bladder and ureter directly with a small camera through the urinary passage. The diagnostic plan is adapted for pregnancy, children, reduced kidney function, and people who should avoid certain contrast agents.

Procedures and treatment options

Treatment aims to protect kidney function, relieve symptoms, treat infection if present, and correct the cause of obstruction. A small stone may pass with pain relief, fluids as advised, and monitoring. Larger or persistent stones may require a stone-removal procedure, such as ureteroscopy or shock-wave treatment, depending on the stone’s size and location.

When urine must be drained promptly, a clinician may place a ureteral stent. This thin internal tube passes from the kidney to the bladder and keeps the ureter open. Another option is a percutaneous nephrostomy, in which a drainage tube is inserted through the skin into the kidney. These measures may be temporary while infection settles, kidney function improves, or definitive treatment is planned.

For strictures, congenital narrowing, prostate-related blockage, or other structural causes, surgery or another targeted procedure may be recommended. Treatment of kidney stones can prevent repeat obstruction when stones are the cause. Antibiotics are used for confirmed or strongly suspected infection, but an infected obstruction often also needs prompt drainage.

The procedure selected should be discussed with a urologist, including expected benefits, alternatives, anesthesia, possible stent symptoms, and the plan for stent or tube removal. A stent or nephrostomy tube must be followed carefully because it is not intended to remain in place indefinitely without medical supervision.

Recovery, follow-up and expected results

Recovery depends on the procedure and the cause of obstruction. After ureteral stent placement, many people return to light activities within a short time, although temporary urinary frequency, urgency, discomfort in the bladder or flank, and small amounts of blood in urine can occur. A nephrostomy tube requires instruction on dressing care, drainage-bag handling, and watching for infection or tube displacement.

Following stone treatment or corrective surgery, the care team may recommend temporary activity limits, hydration guidance, symptom control, and a follow-up appointment. It is important to attend planned imaging and blood-test visits, since they confirm that urine is draining and kidney function is recovering as expected.

Results are generally best when obstruction is recognized and relieved early. Kidney function can improve after drainage, but the extent of recovery varies with the duration and severity of blockage, repeated infections, pre-existing kidney disease, and whether one or both kidneys were involved. Some people need ongoing monitoring or additional treatment if narrowing or stones recur.

Acıbadem Health Point’s multidisciplinary specialists and JCI-accredited hospitals diagnose and treat hydroureteronephrosis for international patients, with care plans based on the individual cause and clinical findings.

Prevention and everyday self-care

Not all cases can be prevented, particularly those related to congenital anatomy, pregnancy, scar tissue, or certain pelvic conditions. However, addressing the underlying cause and attending follow-up appointments can reduce the chance that an obstruction remains unnoticed or returns.

For people with a history of stones, prevention may include drinking fluids regularly according to a clinician’s advice, avoiding excessive salt intake, maintaining a balanced diet, and completing a metabolic stone evaluation when recommended. Dietary changes should be tailored to the type of stone rather than based on general restrictions alone.

People using a stent or nephrostomy tube should follow the care instructions provided by their team. They should not attempt to remove, reposition, or clamp a tube themselves. New fever, escalating pain, leaking around a tube, reduced drainage, or a tube that has moved should be reported promptly.

When to seek medical care

Urgent medical assessment is needed for fever or chills with flank pain or urinary symptoms, severe or worsening pain, repeated vomiting, confusion, very little urine, or inability to urinate. These symptoms may indicate infection, significant obstruction, dehydration, or impaired kidney function and should not be managed solely at home.

Medical review is also appropriate for visible blood in the urine, recurrent urinary tract infections, new persistent side or back pain, or urinary symptoms in someone with a known history of stones, urinary tract surgery, or kidney disease. Pregnant people and those with one functioning kidney should seek advice promptly if obstruction is suspected.

Anyone with a known ureteral stent or nephrostomy tube should contact their care team for fever, worsening discomfort, foul-smelling urine, blocked drainage, or accidental tube movement. Timely evaluation helps clinicians decide whether imaging, drainage, antibiotics, or another intervention is needed.

Frequently asked questions