Hydronephrosis

Hydronephrosis is a condition characterized by swelling of one or both kidneys due to the buildup of urine. This occurs when urine cannot drain properly from the kidney to the bladder, often due to an obstruction or blockage in the urinary tract. While hydronephrosis itself is not a disease but rather a structural condition resulting from other underlying problems, it can lead to kidney damage if left untreated. The condition can affect people of all ages, from unborn babies to elderly adults, and ranges from mild to severe depending on the degree of kidney swelling and the underlying cause.

Medical Disclaimer: This information is for educational purposes only and should not replace professional medical advice. If you suspect you have hydronephrosis or experience severe abdominal or back pain, seek immediate medical attention.

Overview

Hydronephrosis occurs when urine backs up into one or both kidneys, causing them to swell. The kidneys are vital organs that filter waste products from the blood and produce urine, which normally flows through tubes called ureters to the bladder. When this flow is disrupted, pressure builds up in the kidney, leading to distension of the renal pelvis and calyces – the kidney's collecting system. This swelling can compromise kidney function and, if severe or prolonged, may result in permanent kidney damage.

The condition can be classified as unilateral (affecting one kidney) or bilateral (affecting both kidneys). Unilateral hydronephrosis is more common and generally has a better prognosis, as the unaffected kidney can compensate for the impaired one. Bilateral hydronephrosis is more serious and requires urgent medical attention as it can rapidly lead to kidney failure. The severity is typically graded from mild to severe based on the degree of kidney dilation observed on imaging studies.

Hydronephrosis can develop suddenly (acute) or gradually over time (chronic). Acute hydronephrosis often presents with severe symptoms and requires immediate treatment, while chronic hydronephrosis may develop slowly with minimal symptoms, making it harder to detect. The condition affects approximately 1 in 100 adults at some point in their lives, with certain populations at higher risk, including pregnant women, elderly men with prostate issues, and individuals with a history of kidney stones.

Symptoms

The symptoms of hydronephrosis can vary significantly depending on whether the condition develops suddenly or gradually, the degree of obstruction, and whether one or both kidneys are affected. Some people with mild hydronephrosis may have no symptoms at all, while others experience severe pain and complications.

Common Symptoms

Urinary Symptoms

  • Decreased urine output or inability to urinate
  • Frequent urination with small amounts
  • Urgent need to urinate
  • Pain or burning during urination
  • Blood in the urine (hematuria)
  • Cloudy or foul-smelling urine

Gender-Specific Symptoms

  • Pain in testicles - men may experience testicular pain due to referred pain
  • Groin pain that may radiate to the genitals
  • In pregnant women, symptoms may be mistaken for normal pregnancy discomfort

Symptoms of Complications

  • Fever and chills (indicating infection)
  • Fatigue and weakness
  • Loss of appetite
  • Swelling in legs or ankles (if kidney function is impaired)
  • High blood pressure
  • Confusion or mental changes (in severe cases)

Chronic Hydronephrosis Symptoms

When hydronephrosis develops slowly over time, symptoms may be subtle or absent:

  • Mild, intermittent flank discomfort
  • Recurrent urinary tract infections
  • Gradual decline in kidney function
  • No symptoms until significant kidney damage occurs

Causes

Hydronephrosis results from any condition that blocks or impedes the normal flow of urine from the kidneys. The obstruction can occur at any point along the urinary tract, from the kidney to the urethra. Understanding the various causes helps in proper diagnosis and treatment planning.

Common Obstructive Causes

Kidney Stones (Nephrolithiasis)

  • Most common cause in younger adults
  • Stones can lodge in the ureter, blocking urine flow
  • May cause sudden, severe hydronephrosis
  • Often associated with extreme pain

Benign Prostatic Hyperplasia (BPH)

  • Common cause in older men
  • Enlarged prostate compresses the urethra
  • Usually causes bilateral hydronephrosis
  • Develops gradually over time

Tumors and Cancers

  • Bladder cancer
  • Prostate cancer
  • Cervical or uterine cancer
  • Retroperitoneal tumors
  • Metastatic cancers affecting the urinary tract

Structural and Anatomical Causes

Congenital Abnormalities

  • Ureteropelvic junction (UPJ) obstruction
  • Ureterovesical junction (UVJ) obstruction
  • Posterior urethral valves (in boys)
  • Ureterocele
  • Duplicated ureter

Acquired Structural Problems

  • Ureteral strictures from surgery or radiation
  • Retroperitoneal fibrosis
  • Pelvic organ prolapse in women
  • Scar tissue from previous infections or surgery

Functional Causes

  • Vesicoureteral reflux: Backward flow of urine from bladder to kidneys
  • Neurogenic bladder: Nerve damage affecting bladder function
  • Pregnancy: Growing uterus can compress ureters
  • Blood clots: Can block ureters after kidney trauma

External Compression

  • Abdominal or pelvic masses
  • Lymphadenopathy (enlarged lymph nodes)
  • Ovarian cysts or tumors
  • Inflammatory conditions affecting nearby organs
  • Endometriosis involving the ureters

Risk Factors

Several factors can increase the likelihood of developing hydronephrosis. Understanding these risk factors can help in early detection and prevention of the condition.

Age and Gender-Related Factors

  • Older men: Increased risk due to prostate enlargement
  • Women of childbearing age: Pregnancy-related hydronephrosis
  • Infants and young children: Congenital abnormalities
  • Middle-aged adults: Higher incidence of kidney stones

Medical Conditions

  • History of kidney stones: Recurrent stone formers at higher risk
  • Urinary tract infections: Can lead to scarring and strictures
  • Diabetes: Increased risk of infections and nerve damage
  • Neurological disorders: Affecting bladder function
  • Previous pelvic surgery: Risk of scar tissue formation
  • Cancer history: Tumors or treatment effects

Lifestyle and Environmental Factors

  • Dehydration: Increases kidney stone risk
  • High-sodium diet: Contributes to stone formation
  • Obesity: Associated with kidney stones and other risk factors
  • Certain medications: Some drugs increase stone risk
  • Family history: Genetic predisposition to stones or structural abnormalities

Pregnancy-Related Risk Factors

  • Multiple pregnancies
  • Large fetal size
  • Polyhydramnios (excess amniotic fluid)
  • Multiple gestations (twins, triplets)
  • Previous pregnancy-related hydronephrosis

Diagnosis

Diagnosing hydronephrosis involves a combination of medical history, physical examination, laboratory tests, and imaging studies. Early and accurate diagnosis is crucial for preventing kidney damage and determining the appropriate treatment approach.

Medical History and Physical Examination

Your healthcare provider will ask about:

  • Nature, location, and duration of pain
  • Urinary symptoms and changes in urination patterns
  • Previous kidney stones or urinary tract infections
  • Family history of kidney problems
  • Current medications and medical conditions
  • Recent surgeries or procedures

Physical examination may reveal:

  • Tenderness in the flank or abdomen
  • Palpable kidney mass (in severe cases)
  • Signs of urinary retention
  • Enlarged prostate (in men)
  • Signs of infection (fever, elevated heart rate)

Laboratory Tests

Urinalysis

  • Checks for blood, infection, and crystals
  • Evaluates kidney function
  • Identifies possible causes like stones or infection

Blood Tests

  • Serum creatinine and BUN: Assess kidney function
  • Complete blood count: Check for infection or anemia
  • Electrolytes: Evaluate kidney's filtering ability
  • Inflammatory markers: If infection suspected

Imaging Studies

Ultrasound (First-line imaging)

  • Non-invasive and no radiation exposure
  • Excellent for detecting kidney swelling
  • Can identify stones, masses, or other abnormalities
  • Safe for pregnant women and children
  • Can measure degree of hydronephrosis

CT Scan

  • Most detailed imaging for kidney and urinary tract
  • Excellent for identifying stones and their location
  • Can detect tumors and other obstructions
  • CT urography provides comprehensive evaluation
  • Involves radiation exposure

MRI

  • Alternative when CT contrast is contraindicated
  • Good for soft tissue evaluation
  • MR urography for detailed urinary tract imaging
  • No radiation exposure

Specialized Tests

Voiding Cystourethrogram (VCUG)

  • Evaluates for vesicoureteral reflux
  • Particularly useful in children
  • Involves catheterization and X-ray imaging

Nuclear Medicine Scans

  • MAG3 or DTPA renal scan
  • Assesses kidney function and drainage
  • Helps determine if obstruction is significant
  • Can differentiate between obstruction and poor function

Cystoscopy

  • Direct visualization of bladder and urethra
  • Can identify bladder tumors or stones
  • Allows for therapeutic interventions

Treatment Options

Treatment for hydronephrosis focuses on relieving the obstruction, preserving kidney function, and addressing the underlying cause. The approach depends on the severity of the condition, the cause of obstruction, whether one or both kidneys are affected, and the patient's overall health status.

Emergency Treatment

Severe hydronephrosis with infection or kidney failure requires immediate intervention:

Urgent Drainage Procedures

  • Percutaneous nephrostomy:
    • Tube placed through skin directly into kidney
    • Provides immediate drainage
    • Performed under local anesthesia with imaging guidance
    • Temporary measure while planning definitive treatment
  • Ureteral stenting:
    • Thin tube placed from kidney to bladder
    • Bypasses obstruction
    • Can be placed cystoscopically
    • May remain for weeks to months

Medical Management

Medications

  • Antibiotics: For concurrent infections
  • Pain management: NSAIDs or stronger analgesics
  • Alpha-blockers: Help pass small stones and improve urine flow
  • Medications for BPH: If prostate enlargement is the cause
  • Corticosteroids: For inflammatory conditions

Conservative Management

  • Observation for mild cases without symptoms
  • Increased fluid intake for small stones
  • Position changes to facilitate drainage
  • Regular monitoring with imaging

Surgical Interventions

Stone Removal Procedures

  • Extracorporeal shock wave lithotripsy (ESWL):
    • Non-invasive stone fragmentation
    • Best for stones less than 2 cm
    • Outpatient procedure
  • Ureteroscopy:
    • Endoscopic stone removal
    • Direct visualization and treatment
    • Can use laser lithotripsy
  • Percutaneous nephrolithotomy:
    • For large or complex stones
    • Direct kidney access through small incision
    • Higher success rate for large stones

Reconstructive Procedures

  • Pyeloplasty:
    • Repairs UPJ obstruction
    • Can be done open, laparoscopic, or robotic
    • High success rate (>95%)
  • Ureteral reimplantation:
    • For UVJ obstruction or reflux
    • Repositions ureter into bladder
  • Ureteroureterostomy:
    • Removal of strictured segment
    • End-to-end anastomosis

Treatment by Underlying Cause

Prostate-Related Hydronephrosis

  • Medical therapy (alpha-blockers, 5-alpha reductase inhibitors)
  • Transurethral resection of prostate (TURP)
  • Laser prostate surgery
  • Open or robotic prostatectomy for large glands

Tumor-Related Hydronephrosis

  • Oncologic treatment (surgery, chemotherapy, radiation)
  • Palliative drainage for advanced cancer
  • Ureteral stenting or nephrostomy

Pregnancy-Related Hydronephrosis

  • Usually resolves after delivery
  • Conservative management preferred
  • Positioning (lateral decubitus)
  • Stenting only if severe symptoms or complications

Long-term Management

  • Regular follow-up imaging
  • Kidney function monitoring
  • Management of risk factors
  • Preventive measures for stone formers
  • Prompt treatment of UTIs

Prevention

While not all cases of hydronephrosis can be prevented, especially those due to congenital abnormalities or cancer, many risk factors can be modified to reduce the likelihood of developing this condition.

Kidney Stone Prevention

  • Hydration: Drink 2-3 liters of water daily
  • Dietary modifications:
    • Reduce sodium intake
    • Limit animal protein
    • Moderate calcium intake (don't eliminate)
    • Reduce oxalate-rich foods if prone to calcium oxalate stones
  • Maintain healthy weight: Obesity increases stone risk
  • Medications: For recurrent stone formers

General Preventive Measures

  • Regular medical check-ups, especially for high-risk individuals
  • Prompt treatment of urinary tract infections
  • Good hygiene practices to prevent UTIs
  • Management of chronic conditions (diabetes, hypertension)
  • Prostate health screening for men over 50
  • Avoid holding urine for extended periods

Lifestyle Modifications

  • Regular physical activity
  • Stress management
  • Avoid excessive use of NSAIDs
  • Limit alcohol and caffeine
  • Quit smoking

When to See a Doctor

Prompt medical attention is crucial for preventing kidney damage and managing hydronephrosis effectively. Certain symptoms and situations require immediate or urgent medical care.

Seek Emergency Care For:

  • Severe flank or abdominal pain that doesn't improve
  • Complete inability to urinate
  • High fever (>101.5°F) with flank pain
  • Blood in urine with severe pain
  • Signs of severe infection (chills, confusion, rapid heart rate)
  • Nausea and vomiting preventing fluid intake
  • Sudden swelling in legs or difficulty breathing

Schedule a Medical Appointment If:

  • Persistent mild to moderate flank or back pain
  • Recurrent urinary tract infections
  • Changes in urination patterns
  • Intermittent blood in urine
  • Previous history of kidney stones with new symptoms
  • Difficulty starting or maintaining urine stream
  • Feeling of incomplete bladder emptying
  • Pain during urination lasting more than 2 days

Related Conditions

Several conditions may be associated with or mistaken for hydronephrosis:

References

  1. Krajewski W, Wojciechowska J, Dembowski J, et al. Hydronephrosis in the course of ureteropelvic junction obstruction: An underestimated problem? Current opinions on the pathogenesis, diagnosis and treatment. Adv Clin Exp Med. 2017;26(5):857-864.
  2. Farrugia MK, Hitchcock R, Radford A, et al. British Association of Paediatric Urologists consensus statement on the management of the primary obstructive megaureter. J Pediatr Urol. 2014;10(1):26-33.
  3. Onen A. Grading of Hydronephrosis: An Ongoing Challenge. Front Pediatr. 2020;8:458.
  4. Tekgül S, Riedmiller H, Hoebeke P, et al. EAU guidelines on vesicoureteral reflux in children. Eur Urol. 2012;62(3):534-542.
  5. Tseng TY, Stoller ML. Obstructive uropathy. Clin Geriatr Med. 2009;25(3):437-443.