OVERVIEW

What is the normal process of urine excretion?

The urinary system consists of four parts from top to bottom: the kidneys, ureters, bladder, and urethra (the first two are collectively called the upper urinary tract, and the latter two are called the lower urinary tract). Blood undergoes filtration, reabsorption, and other processes in the renal parenchyma to form urine.

Urine gradually drains from the renal pelvis into the ureters and bladder, and is eventually expelled from the body through the urethra.

What does vesicoureteral reflux mean?

Normally, the bilateral ureters contract 2 to 10 times per minute, transporting urine from the kidneys to the bladder. However, due to the anti-reflux structure formed by the ureters and bladder, urine does not flow backward into the ureters.

When various factors damage the anti-reflux function of the vesicoureteral structure, urine may flow backward from the bladder into the ureters, which is called vesicoureteral reflux.

Is vesicoureteral reflux a disease?

Vesicoureteral reflux is a type of ureteral malformation. When it causes ureteral dilation, increased intraureteral pressure, renal pelvis dilation with hydronephrosis, and compression of the renal parenchyma, it is referred to as vesicoureteral reflux syndrome.

Is vesicoureteral reflux common?

The incidence of primary vesicoureteral reflux in normal children is 1%–18.5%, but 70% of cases are associated with urinary tract infections. If left untreated, it can persist into adulthood. The occurrence of secondary cases depends on the underlying disease and the extent of treatment.

SYMPTOMS

What are the manifestations of vesicoureteral reflux?

The symptoms of this condition are related to its severity. Mild cases may cause no discomfort, while severe cases often present with:

• Urinary irritation symptoms: Due to urine reflux, patients are prone to upper urinary tract infections, which may lead to persistent symptoms such as frequent urination, urgency, and dysuria.

• Lumbar or abdominal pain: Often manifests as soreness or discomfort in the affected side of the lower back, especially when holding urine or straining to urinate. The increased pressure in the upper urinary tract due to reflux can cause distending pain.

• Renal insufficiency: Persistent high pressure in the upper urinary tract caused by reflux compresses the renal parenchyma and impairs urinary function. Bilateral involvement may lead to renal insufficiency.

• Hypertension: Compression of the renal parenchyma affects blood supply, potentially causing secondary hypertension, a common late-stage complication and a frequent cause of malignant hypertension in children.

• Others: Some patients may experience delayed growth, nausea, vomiting, or other symptoms.

Of course, these symptoms are nonspecific (i.e., the condition cannot be diagnosed based on symptoms alone). However, when multiple symptoms occur in children, the possibility of this disease should be considered.

How is the severity of vesicoureteral reflux assessed?

According to the classification proposed by the International Reflux Study Committee, the condition is divided into five grades:

• Grade I: Reflux occurs but only reaches the ureter (mildest form, with no reflux reaching the kidneys).

• Grade II: Reflux reaches the renal pelvis and calyces but without dilation.

• Grade III: Mild dilation or tortuosity of the ureter, mild dilation of the renal pelvis, and slight blunting of the fornices.

• Grade IV: Moderate dilation or tortuosity of the ureter, moderate dilation of the renal pelvis and calyces, but most calyces retain their papillary shape.

• Grade V: Severe dilation or tortuosity of the ureter, severe dilation of the renal pelvis and calyces, with most calyces losing their papillary morphology (most severe form).

CAUSES

What are the causes of vesicoureteral reflux?

The disease is classified into primary and secondary types based on etiology, including:

• Primary: Most common, referring to congenital or present-at-birth abnormalities in the anti-reflux structure of the ureter and bladder without other external causes. Main manifestations include abnormal ureteral orifice morphology or position, paraureteral diverticula, and are often accompanied by bladder dysfunction.

• Secondary: Caused by other underlying conditions, such as recurrent urinary tract infections, urinary tuberculosis, lower urinary tract obstructive diseases (e.g., urethral stricture, benign prostatic hyperplasia), as well as pregnancy or trauma.

Is vesicoureteral reflux related to genetics?

Studies indicate that children of patients with primary vesicoureteral reflux have an incidence rate of approximately 66%.

DIAGNOSIS

What tests are needed to diagnose vesicoureteral reflux?

Tests required include urinalysis, urine culture + drug sensitivity, urinary tract ultrasound, non-contrast + contrast-enhanced CT of the urinary tract, cystoscopy, voiding cystourethrography, and renal function tests.

What are the purposes of the auxiliary examinations for vesicoureteral reflux?

Each test has different advantages, disadvantages, and indications, so multiple tests are often required to further clarify the condition:

• Urinalysis: Detects the presence of white blood cells, red blood cells, urinary protein, and urine pH. In cases of urinary tract infection, it may show increased white blood cells. Some patients may later test positive for urinary protein.

• Urine culture + drug sensitivity: This test requires midstream urine collection. Its purpose is to identify the pathogenic bacteria and determine antibiotic sensitivity or resistance. However, it takes longer than urinalysis, and some bacteria (e.g., Mycobacterium tuberculosis) may not grow in standard cultures. While not diagnostic for this condition, it guides antibiotic selection for urinary tract infections.

• Renal function tests: A blood test measuring creatinine and blood urea nitrogen levels to assess overall kidney function. Individuals with only one kidney may still show normal renal function.

• Urinary tract ultrasound: Simple, convenient, non-invasive, and can be performed bedside, but results may be affected by intestinal gas and operator experience. It also lacks detailed imaging for clinicians. It serves as both an initial screening tool and a follow-up method.

• Non-contrast + contrast-enhanced CT of the urinary tract: Uses X-rays and is more expensive. Early-stage disease may lack characteristic findings, but it helps rule out other conditions like urinary stones.

• Voiding cystourethrography: Requires infection control before testing to avoid worsening infection. A catheter injects contrast into the bladder, allowing dynamic imaging during urination to detect reflux into the ureters. It confirms diagnosis and assesses severity but requires patient cooperation and is time-consuming.

• Cystoscopy: Limited diagnostic value for this condition. Similar to gastrointestinal endoscopy, it is invasive and usually performed after imaging. It directly examines ureteral orifice morphology, position, and possible diverticula, with optional biopsy. Risks include bleeding and infection, and it should not be performed during acute infection.

TREATMENT

Which department should patients with vesicoureteral reflux go to for treatment?

Generally, patients should visit the urology or nephrology department. However, for pediatric patients, symptoms may be atypical or the child may be unable to clearly express their condition, so they often first visit the pediatrics department. In emergencies, go to the emergency department.

How should vesicoureteral reflux be treated?

The main goals of treatment are to protect kidney function, prevent urine backflow, and control urinary tract infections. The treatment plan is determined based on the severity of the condition, the control of urinary tract infections, and the patient's age. Current treatment options include conservative treatment and surgical treatment:

• Conservative treatment: Suitable for children with primary reflux or mild cases.

  • Regular check-ups are required, including a monthly urinalysis, a urine culture + sensitivity test every 3 months, and a cystogram every 4–6 months.

  • During conservative treatment, urinary tract infections should be actively treated if they occur.

  • Additionally, daily prophylactic antibiotics may be given. Commonly used antibiotics for prevention include trimethoprim-sulfamethoxazole, trimethoprim alone, or nitrofurantoin. Antibiotic prophylaxis usually continues until vesicoureteral reflux resolves spontaneously or is surgically corrected.

• Surgical treatment: Suitable for patients with poorly controlled urinary tract infections or severe conditions. The main surgical method is ureterovesical reimplantation.

What complications can vesicoureteral reflux cause?

The ureter primarily functions to transport urine produced by the kidneys to the bladder, so the disease mainly affects the kidneys.

In addition to producing urine through the glomeruli and renal tubules, the kidneys also regulate blood pressure, secrete hormones that promote red blood cell production, and perform other functions.

Therefore, long-term or severe vesicoureteral reflux can lead to reduced kidney function, kidney failure, and hypertension. Additionally, children with this condition may experience impaired kidney development.

DIET & LIFESTYLE

Can vesicoureteral reflux heal on its own?

Vesicoureteral reflux has a certain spontaneous resolution rate, which generally decreases with age. However, it still requires attention and regular check-ups.

Do patients with vesicoureteral reflux need follow-up?

This condition requires long-term follow-up, primarily including annual evaluations of height and weight, blood pressure measurements, and urine analysis.

Patients should be aware that vesicoureteral reflux (VUR) is associated with an increased risk of chronic kidney disease (CKD), such as hypertension, impaired renal function, or proteinuria.

PREVENTION

None.