Ureteropelvic junction obstruction

Disease Description (Causes and Symptoms)

• Definition: A condition in which the ureteropelvic junction (UPJ) becomes narrowed or blocked, causing dilation of the renal pelvis (renal pelvis and calyces) and leading to hydronephrosis and renal parenchymal damage.
• Main causes
  • Congenital abnormalities (most common)
  • Compression by a crossing vessel that crosses the ureter
  • Stricture or scarring caused by surgery, trauma, or inflammation
  • Ureteral stones or stricture after ureteroscopic procedures
• Pathophysiology: Impaired urine drainage due to UPJ stricture causes increased pressure in the renal pelvis → dilation of the renal pelvis and calyces (hydronephrosis); if prolonged, renal parenchymal atrophy and declining renal function may occur
• Main symptoms
  • Children: Abdominal distension or an abdominal mass, growth delay, poor appetite, fever (in cases of infection)
  • Adolescents and adults: Flank pain (intermittent, colicky pain), urinary tract infection, hematuria, vomiting, or no symptoms in some cases
  • Complications may include hypertension, recurrent urinary tract infections, and declining renal function

Treatment Methods

• Diagnostic test summary
  • Abdominal ultrasound: Confirmation of hydronephrosis (noninvasive first-line test)
  • CT (including urography): Identification of anatomical causes (e.g., crossing vessels)
  • Nuclear medicine study (diuretic renogram; MAG3, etc.): Assessment of delayed drainage and split renal function between the two kidneys (important for determining treatment indications)
• Conservative treatment
  • Regular imaging follow-up when the patient is asymptomatic and split renal function is preserved (e.g., only mildly reduced)
  • Antibiotic treatment for urinary tract infections, pain control, and hydration
• Interventional and surgical treatment
  • Pyeloplasty: Standard treatment. The narrowed segment is removed and the ureter is reconnected (open, laparoscopic, or robotic surgery is possible). Applicable to both children and adults.
  • Balloon dilation of the ureter and endoscopic incision (endopyelotomy): Selective indications, with limited success rates depending on the cause, location, and characteristics of the lesion.
  • Ureteral stent (double-J) placement or percutaneous nephrostomy drainage: Temporary treatment when immediate decompression is needed due to acute obstruction or infection.
• Medication treatment
  • Symptom control (analgesics) and antibiotics in cases of infection
  • Antihypertensive medication management when hypertension is present
• Precautions/Risk of complications
  • Delayed treatment increases the risk of permanent decline in renal function and hypertension
  • Urinary leakage, infection, and recurrent stricture may occur after surgery (repeat surgery may be necessary)
  • General complications related to procedures and anesthesia should be considered
• Self-care
  • Drink sufficient fluids, and visit a medical institution immediately if abnormal symptoms such as hematuria, pain, or fever occur after urination
  • Take medications as prescribed, keep examination appointments, and undergo follow-up imaging

Checklist Before an Outpatient Visit (Including Sample Questions)

• What to bring
  • A list of all medications and supplements currently being taken
  • Records of previous surgeries, hospitalizations, and urinary tract-related procedures
  • Recent imaging test results (preferably the original files), including ultrasound, CT, and renogram results, and the radiology reports
  • Symptom diary: Timing, frequency, and intensity of pain; presence of fever, hematuria, or vomiting; and history of infections
  • Urinalysis results, if available and recent, and blood pressure records (if hypertension is suspected)
• Information to provide to the doctor during the outpatient visit
  • When the symptoms began and how they have changed
  • Whether there have been changes in the child's growth or nutritional status
  • Possibility of pregnancy (for women)
• Sample questions (sentences patients can prepare in advance)
  • "I will bring the results of my most recent kidney ultrasound/renogram so that we can review them together."
  • "I have written down how often the pain occurs and how long it lasts when it is severe."

Examples of General Questions to Ask the Doctor

• "What are my split renal function (the proportion of function between the two kidneys) and absolute renal function values?"
• "What are the criteria for recommending surgery (such as declining renal function, recurrent infections, or pain)?"
• "Which surgical approach—open, laparoscopic, or robotic—is most appropriate for me, and why?"
• "What are the major complications and recurrence rate of the surgery or procedure?"
• "What tests are needed before and after surgery, and how often should I have outpatient follow-up?"

Examples of Condition-Specific Questions

• "At what split renal function level would you choose conservative treatment, and at what level would you recommend surgery based on the nuclear medicine study?"
• "A crossing vessel is visible on the imaging. In this case, what are the success rate and risk of recurrent stricture with robotic or laparoscopic pyeloplasty?"