What causes swollen kidneys?
Swollen kidneys, also known as hydronephrosis, occurs when urine cannot drain from the kidney into the bladder. This causes a backup of urine in the kidney, leading it to swell and become enlarged. Some common causes of hydronephrosis include:
- Kidney stones – Kidney stones that become lodged in the ureter can block the flow of urine from the kidney. This is one of the most common causes of hydronephrosis.
- Enlarged prostate – An enlarged prostate, usually caused by benign prostatic hyperplasia (BPH), can compress the urethra and obstruct urine flow from the bladder. This can cause a backup of urine into the kidneys.
- Kidney cysts – Fluid-filled sacs called cysts can develop on the kidneys and block urine drainage.
- Scar tissue – Scarring from prior infections, surgery or trauma can narrow or block the ureters.
- Tumors – Cancerous or benign tumors in the abdomen, pelvis or urinary tract can compress ureters.
- Birth defects – Congenital abnormalities of the urinary tract, such as ureteropelvic junction (UPJ) obstruction, can impede urine flow.
- Pregnancy – The enlarging uterus can compress the ureters, especially later in pregnancy.
The most common cause of hydronephrosis in adults is kidney stones. In children, it is most often due to congenital urinary tract abnormalities.
What are the symptoms of swollen kidneys?
The symptoms of swollen kidneys can vary depending on the underlying cause and severity of the obstruction. Common signs and symptoms include:
- Flank pain – A dull ache or sensation of fullness in one or both sides of the lower back. This is where the kidneys are located.
- Abdominal pain – Pain in the belly or pelvic area from urine backup.
- Nausea and vomiting – Can occur from irritation and stretching of the ureters and renal capsule.
- Fever – May develop from a kidney infection triggered by urine stasis.
- Decreased urine output – Obstruction impairs urine flow from the kidneys.
- Blood in urine – Can indicate irritation in the urinary tract.
- Swelling – Fluid retention and edema in the legs and feet.
In mild hydronephrosis, there may be no symptoms. Severe cases can lead to kidney damage, infection, kidney failure, and sepsis if left untreated. Seeking prompt medical care for evaluation is important.
How is hydronephrosis diagnosed?
If hydronephrosis is suspected based on symptoms and exam, the doctor will order imaging tests to confirm the diagnosis and determine the cause. Common diagnostic tests include:
- Renal ultrasound – This uses sound waves to create images of the kidneys and urinary tract. It can detect obstruction and measure the degree of swelling.
- CT scan – CT imaging provides more detailed views of the kidneys and surrounding structures to pinpoint the obstruction.
- Intravenous pyelogram (IVP) – This involves injecting contrast dye into the bloodstream to outline the urinary tract on x-rays.
- Voiding cystourethrogram – A catheter injects contrast dye into the bladder during urination to visualize flow on x-rays.
- Retrograde pyelogram – Contrast dye is injected through a urinary catheter to highlight the ureter and renal pelvis.
These studies help differentiate between unilateral vs bilateral kidney involvement, locate obstructions, assess kidney function, and guide treatment. Blood and urine tests may also be done to check for infection and kidney function.
How is hydronephrosis treated?
Treatment for swollen kidneys involves relieving the obstruction and draining backed up urine from the kidney. This helps prevent permanent kidney damage from pressure and infection. Treatment options depend on the cause and may include:
Treating underlying conditions
If hydronephrosis is due to an enlarged prostate, kidney stones, cysts or tumors, treating the underlying problem may resolve obstruction. Examples include:
- Medications to shrink enlarged prostate
- Surgery to remove prostate tissue
- Lithotripsy to break up kidney stones
- Surgery to remove abnormally positioned kidneys or tumors
- Draining fluid from kidney cysts
Stenting/nephrostomy tube
Inserting a thin plastic stent between the kidney and bladder or a nephrostomy drainage tube into the kidney can provide temporary relief while awaiting surgery. This immediately decompresses the urine buildup.
Ureteral surgery
Different surgical procedures can redirect urine flow around the obstruction site:
- Ureteral reimplantation – Relocating one ureter to drain urine flow into the bladder.
- Ureteroureterostomy – Connecting the ureters together to bypass an obstruction.
- Ureteroneocystostomy – Attaching the ureter to a new opening in the bladder.
Nephrectomy
If the kidney is severely damaged or nonfunctional, surgical removal may be needed. However, every effort is made to preserve kidney function if possible.
What is the prognosis for hydronephrosis?
With prompt treatment, the outlook for hydronephrosis is generally good. However, some factors that can impact prognosis include:
- Cause – Kidney stones or enlarged prostate have better outcomes than cancer.
- Severity – Mild cases have better prognosis than severe hydronephrosis.
- Kidney function – Preserving as much kidney function as possible is optimal.
- Age – Children tend to have good outcomes with early treatment.
- Comorbidities – Coexisting medical conditions can increase complications.
- Treatment response – Favorable response to drainage and surgery improves prognosis.
In mild cases causing no permanent kidney damage, hydronephrosis may resolve completely after treatment. With severe cases or delayed treatment, the affected kidney may be permanently damaged or require removal. Lifelong kidney function monitoring is often needed.
With bilateral hydronephrosis involving both kidneys, urgent drainage is needed to prevent life-threatening complications. Ongoing kidney care is crucial to maintain function. Overall, working closely with a nephrologist and urologist helps optimize outcomes.
Conclusion
Hydronephrosis occurs when urine drainage from the kidneys to the bladder becomes obstructed, causing the kidneys to swell. It is often caused by kidney stones, enlarged prostate, tumors or congenital abnormalities. Symptoms include flank pain, abdominal pain, nausea, fever and decreased urine output. Diagnostic imaging such as ultrasound, CT scan and pyelogram confirm the diagnosis and locate obstructions.
Treatment involves relieving the obstruction through procedures such as stenting, surgery or nephrectomy. The prognosis depends on the cause, severity, kidney function and comorbidities. With prompt treatment, outcomes can be good in many cases. Lifelong monitoring and follow-up care with a nephrologist is important, especially with severe or bilateral hydronephrosis.
| Cause | Symptoms | Diagnosis | Treatment |
|---|---|---|---|
| Kidney stones | Flank pain, nausea, vomiting, fever | CT scan, ultrasound | Lithotripsy, stenting, surgery |
| Enlarged prostate | Abdominal pain, decreased urine output | Urinalysis, retrograde pyelogram | Medications, prostate surgery |
| Kidney cysts | Back pain, swelling in legs | Ultrasound, MRI | Draining cysts, surgery |
| Ureteropelvic junction obstruction | Asymptomatic, flank pain | Intravenous pyelogram | Ureteral reimplantation surgery |
| Pregnancy | Flank pain, nausea | Renal ultrasound | Observation, stenting |
| Tumors/cancer | Blood in urine, weight loss | CT scan, biopsy | Surgery, chemotherapy, radiation |
This table summarizes the common causes, symptoms, diagnosis, and treatments for hydronephrosis resulting in swollen kidneys. The key is to identify the underlying cause and relieve any obstructions to preserve kidney function. Imaging tests and selective use of stents, surgery or other procedures tailored to the specific situation are utilized. Consultation with urologists and nephrologists helps guide optimal management.
Tips for preventing hydronephrosis
While not all cases can be prevented, some tips to help reduce risk of developing hydronephrosis include:
- Drink plenty of fluids to avoid concentrated urine and kidney stones.
- Manage medical conditions like diabetes and high blood pressure.
- Get regular prostate exams if at higher risk for BPH.
- Avoid kidney toxins in foods, chemicals and medications when possible.
- Treat urinary tract infections promptly.
- Use proper technique and safety gear for contact sports to prevent trauma.
- Receive routine prenatal care during pregnancy.
- Stay vigilant for symptoms and report any concerns promptly.
Discuss any personal or family history of urinary tract/kidney issues with your doctor to determine optimal prevention strategies. Catching problems early is key to preserving kidney function with hydronephrosis.
