Hydronephrosis (Hydronephrosis)
1) Disease Description (Causes and Symptoms)
- Definition: A condition in which the renal pelvis (the space where urine collects in the kidney) becomes dilated due to excessive accumulation of urine. If it progresses, compression of the kidney may lead to reduced kidney function.
- Main causes: Urinary tract obstruction (ureteral stricture, ureteral stone, tumor, congenital obstruction—especially ureteropelvic junction [UPJ] obstruction), vesicoureteral reflux (VUR), trauma, surgery, or infection, and ureteral compression caused by pregnancy. In children, UPJ obstruction and VUR are common.
- Pathophysiology: Obstruction of urine flow causes dilation of the renal pelvis and calyces and increases pressure inside the kidney, compressing and causing ischemia of the renal parenchyma (renal corpuscles and tubules), which leads to reduced function. If it persists, renal atrophy and loss of kidney function may occur.
- Main symptoms: Asymptomatic (especially common in the early stages), flank pain or back/abdominal pain, vomiting and nausea, fever (when accompanied by a urinary tract infection), urinary frequency or difficulty urinating, and a palpable mass in the abdomen or flank. It is often detected on prenatal ultrasound.
- Diagnostic tests (summary): Renal ultrasound (first-line test), voiding cystourethrography (VCUG, to check for VUR in children), nuclear medicine renal function testing (diuretic renography; MAG3/DTPA) to assess drainage function and differential renal function, and additional imaging such as CT/MR when necessary.
2) Treatment Methods
- Observation (conservative management)
- If there are no symptoms or no effect on kidney function, follow-up with regular ultrasound and functional testing. Some mild lesions in children may resolve spontaneously.
- Medication
- If there is a urinary tract infection, antibiotic treatment based on culture results (long-term prophylactic antibiotics may be considered in some children). Analgesics and anti-inflammatory drugs for pain relief.
- In general, there are no specific approved medications that dissolve or reverse hydronephrosis itself; treating the underlying cause is essential.
- Procedures/Surgery
- In cases of obstruction inside the ureter (such as a ureteral stone or stricture), endoscopic removal or stent placement (ureteral stent).
- For ureteropelvic junction (UPJ) obstruction, definitive corrective surgery (e.g., pyeloplasty) is the standard treatment for a single lesion.
- In cases of acute, severe obstruction of urine drainage (severe pain, infection, or worsening kidney function), immediate drainage with percutaneous nephrostomy (PCN, nephrostomy).
- Bladder surgery or ureteral reconstruction may be necessary depending on the cause, such as bladder or urethral abnormalities or VUR.
- Lifestyle management and precautions
- Drink sufficient fluids (to prevent dehydration) and use caution with nephrotoxic drugs (e.g., excessive use of NSAIDs and some antibiotics/contrast agents).
- Seek medical attention promptly if symptoms of a urinary tract infection occur (fever, painful urination, or urinary frequency). If symptoms occur during pregnancy, consultation between obstetrics and gynecology and urology is necessary.
- Follow-up after treatment
- Regularly assess residual hydronephrosis and differential renal function with ultrasound and functional testing. Early treatment is important for preserving kidney function.
3) Outpatient Visit Checklist (Including Items to Bring and Example Questions)
- Items to bring
- A list of currently used medications (including prescription drugs, OTC drugs, and herbal medicines)
- Copies or summaries of previous test results (ultrasound, blood and urine tests, nuclear medicine tests, CT/MRI, etc.)
- A record of changes in symptoms (when they began, what symptoms occurred, fever, pain, changes in urination, etc.)
- Pregnancy status (for women); for children, birth history, growth records, etc.
- Items to check in advance at the outpatient visit
- Whether there has recently been fever, chills, or severe flank pain
- Changes in urine volume (decrease) and whether there is blood in the urine
- Recent history of urinary tract infections or antibiotic use
- Example questions (Patient → Doctor)
- "What is the degree of hydronephrosis on my recent ultrasound?"
- "What lifestyle habits should I follow to protect my kidney function?"
4) Examples of General Questions to Ask the Doctor
- What are the side effects of this medication (or procedure), and what is the expected recovery period?
- Given my current condition, is surgery necessary now, or can I continue with observation?
- What tests should I undergo, and at what intervals, to preserve my kidney function in the future?
- Are there any special precautions if I am pregnant (or planning to become pregnant)?
5) Examples of Disease-Specific Questions
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For parents of children (infants and young children): "Is there a possibility that my child's hydronephrosis will improve spontaneously? If we observe it without surgery, what criteria would indicate that surgery is recommended?"
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For adults (related to urinary stones): "If a ureteral stone is the cause, how will it be removed (extracorporeal shock wave therapy, endoscopy, a stent, etc.)? How should I manage my lifestyle and diet to prevent recurrence?"
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Urgent warning (additional)
- Fever, severe flank pain, a sudden marked decrease in urine volume, confusion, and similar symptoms may indicate an emergency; prompt medical attention or a visit to the emergency room is recommended.