What Is Reflux Nephropathy?

Reflux nephropathy is a type of interstitial nephropathy. It is characterized by irregular large scars on the surface of the kidneys, enlarged and deformed kidneys, enlarged and deformed cortex, and bladder ureteral reflux (VUR). For "chronic atrophic pyelonephritis". Urinary bladder reflux may be unclear or disappear when a scar is detected, and some cases are characterized by recurrent urinary tract infections (UTI). Due to the degree of scar formation, renal damage can be localized and diffuse.

Basic Information

nickname: Reflux nephropathy
English name: reflux nephropathy
Visiting department: Nephrology

Common locations: kidney
Common causes: Bladder ureteral reflux
Common symptoms: Urinary tract infection, abdominal pain during urination

Causes of reflux nephropathy

The cause of reflux nephropathy is bladder ureteral reflux. Urinary bladder reflux is the reflux of urine through an imperfect bladder-ureter junction. Physiologically, the full performance of the anatomical function of the valve mechanism of the last segment of the ureter prevents this reflux. This valve mechanism includes: the ureter obliquely passes through the bladder wall; the special muscle tissue of the ureter wall; and the ureteral mucosal flap. Changes in the anatomical functional integrity of the aforementioned valve mechanism will lead to primary or secondary bladder ureteral reflux.

Primary bladder ureteral reflux

Primary bladder ureteral reflux is clinically most common. More common in children. It is a congenital abnormality of the bladder submucosal ureter segment, such as congenital bladder submucosal ureter is too short, the bladder deltoid muscle tissue is poorly developed. As the child grows, the base of the bladder develops, and most of the reflux will disappear.

2. Secondary bladder ureteral reflux

Secondary bladder ureteral reflux can be secondary to bladder neck or urethral obstruction (bladder hypertension), neurogenic bladder (cystic muscle weakness), bladder tuberculosis, and bladder surgery (causing ureteral injury).

3. Classification of bladder ureteral reflux

The widely accepted classification criteria for the degree of reflux proposed by the International Children's Bladder and Ureteral Reflux Study Group:

(1) Grade I only affects the ureter.

(2) Grade involved the ureter and renal pelvis, no expansion of the renal calyces, and normal renal cavities.

(3) Grade III ureter is slightly and moderately dilated and / or curved, the renal pelvis is slightly and moderately dilated, and the vault is not or only slightly dull.

(4) Moderate dilatation and / or bending of grade IV ureters, moderate dilatation of the renal pelvis and calyces, disappearance of the acute angle of the dome but most of the shape of the nipples of the renal calyx.

(5) Grade V ureters and renal pelvis and renal pelvis are severely dilated and bent, and the shape of the nipples of most renal pelvis disappears.

Clinical manifestations of reflux nephropathy

The clinical manifestations of reflux nephropathy vary. The number of episodes of urinary tract infection and the severity of symptoms have nothing to do with the degree of reflux and the degree of renal scarring. Cases with only one infection history can also have severe reflux. Children with the first urinary tract infection should be examined regardless of age, sex, and severity of symptoms. Children often develop symptoms under the age of 4 and see a recurrent urinary tract infection. Medical patients are mostly young women and young people, and they often come to the clinic for unilateral renal atrophy, renal failure, urinary tract infection symptoms, and hypertension.

The most common clinical manifestations of reflux nephropathy are urinary tract infections and flank pain that occurs most often during urination. The incidence of urinary tract infections is 63% to 88%; the incidence of proteinuria is 34.5% to 54.7%. It can also be the first symptom of reflux nephropathy, which often appears after several years of severe scar formation, suggesting bladder ureteral reflex Flow has caused glomerular disease, which is an indication of a poor prognosis. Even after the bladder ureteral reflux disappeared, renal function continued to deteriorate. In addition, the disease also has latent characteristics, often found for the first time during pregnancy due to urinary tract infection, proteinuria, hypertension, preeclampsia or renal failure. Individual patients occasionally underwent imaging studies for other reasons and were found to have single or double kidney scars or atrophy, or the diagnosis of this disease was considered due to the discovery of asymptomatic bacteriuria. Some cases may be asymptomatic for a long period of time, and it is not diagnosed until renal insufficiency enters the uremia stage.

Hypertension is common during the course of reflux nephropathy, with 75% of patients beginning dialysis having hypertension. Hypertension can also occur years after successful antireflux surgery. There was no significant correlation between the severity of hypertension and the degree of reflux and urinary tract obstruction. The clinical incidence of hypertension is 10.6% to 38.1%, which is a common late-stage complication of reflux nephropathy; pregnancy hypertension (pregnancy-induced hypertension) can be the first symptom of reflux nephropathy. About 4% of patients with severe PIH have reflux nephropathy; nocturia, polyuria, and abnormal urine concentration may be present; 10.2% to 50% of reflux nephropathy can cause renal failure, and renal failure generally occurs Under 35 years of age. Nitroemia is already present in about half of the cases. Renal failure in unilateral reflux nephropathy is due to concurrent glomerular disease in both kidneys. The disease can also have a history of enuresis (4% to 20%), kidney stones (2.2% to 18%), microscopic or gross hematuria.

Reflux nephropathy

Laboratory inspection

(1) Urine test: Leukocyte urine or pyuria can be seen during urinary tract infection, and urine culture is positive; white blood cells, red blood cell casts, and renal tubular proteinuria, microscopic hematuria, urine specific gravity, and urine osmotic pressure are significantly reduced. Such as the manifestation of renal damage, urine NAG enzymes increased, urine ₂ -MG increased. Hypoconcentration and reduced ₂ microglobulin reabsorption indicate impaired tubule function, and proteinuria greater than 1 g / day suggests secondary focal segmental glomerulosclerosis.

(2) Blood examination . Systemic infectious symptoms such as increased blood leukocytes and nuclear shift to the left can be seen. Tamm-Hosfall antibody is positive, IgG is elevated, and azotemia and elevated serum creatinine levels may occur during acute renal failure. Hypernatremia can occur when falling.

2. Other auxiliary inspections

(1) Renal biopsy The pathological changes in the typical cases of this disease are mainly scar formation of the cortical papilla, dilation and twisting of the calves. The lesions are most prominent in the lower and upper poles of the kidney. The lesions can be unilateral or bilateral. Shrinking can also be extremely shrinking. If a large amount of reflux continues, ureteral dilatation and bending can be seen.

(2) Histological examination The renal histological damage of reflux nephropathy is actually not significantly different from that of chronic pyelonephritis. It can be seen that lymphocyte infiltration, interstitial fibrosis, and tubule degenerative changes. Glial casts are often found in atrophic tubes. It showed cystic dilatation of tubules, the glass-like changes or disappearance of glomeruli, arterioles and interlobular arteries were blocked due to contraction and intimal thickening. In some cases, light staining substances containing Tamm-Horsfall protein were seen in the outer medullary zone and cortex. This lesion is often surrounded by accumulated lymphocytes and plasma cells. In cases with urinary tract infections, cortical atrophy is often accompanied by a severely distributed inflammatory response and can extend from the damaged medulla to the entire leaflet. At this time, it is common for the kidney to shrink, the pelvis and pelvis to expand, and the cortex to become thin. There is a focal scar on the surface of the kidney.

(3) Light microscopy and electron microscopy showed that renal tubular atrophy, renal interstitial fibrosis, lymphocyte infiltration, THP circular stains in the cortex and outer pulp, and glomerular bureaucracy in advanced lesions. Focal sclerosis, IgM, IgG, and C3 deposition in some glomeruli can be seen by fluorescence microscopy. Electron microscopy revealed electronically dense deposits under the endothelium.

3. Imaging examination

(1) Urography: The most typical change in this disease is focal cortical scars that correspond to distorted sacral calculus. Residual lobes can be compensated for hypertrophy and present pseudotumor images. Generally speaking, the urography of patients is typical and appears as a "standard" image. Kidney scars correspond to twisted and club-shaped enlarged calyces, and the normal cortex alternates.

(2) Ultrasound ultrasound showed irregular kidney shape, fibrous scar showed enhanced reflex, and compensatory hypertrophy showed normal reflex. The results of ultrasound and excretory urography were consistent in 94% of the cases. Ultrasonography is not as sensitive in detecting renal papillary morphology as intravenous pyelography, but it can detect renal scars sensitively. Intravenous pyelography is less effective for this.

(3) Kidney scan Kidney scan can be used as a supplementary method for the diagnosis of reflux nephropathy. The most commonly used radionuclide is ⁹⁹ Tc, which has good physical properties. There are 3 different ⁹⁹ Tc labeled complexes available for clinical use. 99Tc-labeled DTPA complex is filtered by the glomerulus, and there is no obvious stay in the renal cortex, so it is particularly useful for evaluating the function of the collective system and determining the total and single glomerular filtration rate. ⁹⁹ Tc-labeled DMSA slowly accumulated in the functional renal cortex gradually with urinary excretion. The DMSA scan defect reflected the decrease of radionuclide excretion in the proximal tubule due to ischemia and hypoperfusion. ⁹⁹ Tc-labeled glucoheptanoate has the above two advantages: most are excreted into the renal pelvis and renal calyx system, but some are retained in the renal cortex. Delayed development 2 to 3 hours after injection is used to detect acute pyelonephritis and cortical scar It is particularly beneficial, but it is not as effective in diagnosing mild renal calyx as intravenous pyelography.

(4) X-ray excretory bladder urethral angiography (VCUG) VCUG is a traditional method for checking reflux, which is valuable for the diagnosis of urethral and bladder wall abnormalities and accurate classification of reflux, but the test is traumatic and painful And it is possible to introduce bacteria into the urethra. The application of digital subtraction in excretory cystourethrography improves the sensitivity and accuracy of diagnosing reflux.

(5) Radionuclide cystography Radionuclide cystography is developed by VCUG, and its radiation dose in the gonad is very low. It has become one of the alternative examination methods in many children's hospitals abroad. Comparing radionuclide cystography and radioactive X-ray excretory cystourethrography (VCUG), the former is now considered to be the most effective method for screening reflux and judging the effect of surgery. Its advantages are low radiation dose; high sensitivity; The obtained data parameters such as residual volume, reverse flow, and bladder volume during reflux. The shortcomings of radionuclide cystography are that it cannot evaluate the urethra; it cannot be graded according to international classification standards; nor can it show slight bladder wall abnormalities such as small diverticulum. The indications of radionuclide cystography are as follows: Patients with reflux undergo medical treatment or follow-up examination after surgery. Screening of asymptomatic siblings of reflux children. Systematic examination of children who are susceptible to bladder ureteral reflux (such as spinal meningocele or other functional bladder diseases). Preliminary screening of female children with UTI.

(6) Computerized tomography (CT) is more accurate for detecting renal cortical scars, but it is more expensive.

Reflux nephropathy diagnosis

1. Changes in high-dose intravenous pyelography and X-ray tomography

(1) Pedestal-shaped deformation of the kidney and scar formation in the adjacent cortex.

(2) The renal cortex becomes thinner, which usually occurs on one or both sides of the kidney poles. The kidney volume is reduced or morphologically disproportionate (the length of the kidneys differs by 1.5 cm).

(3) The pelvis and ureter of the renal pelvis are dilated without organic obstruction.

Bladder ureteral reflux

Different degrees of bladder ureteral reflux can be found, but about half of adult cases can be free of bladder ureteral reflux.

3. Other

Secondary bladder ureteral reflux is ruled out. At this time, bladder ureteral reflux is often bilateral.

Reflux nephropathy treatment

Prevention and treatment of urinary tract infection

Empty the bladder regularly. The most important thing is 2 urinations (2 urinations in 5 minutes). Long-range low-dose bacteriostatic therapy is most commonly used. Take sulfamethoxazole / trimethoprim after urination every night before bed. Xin Nuoming) for half a month for 6 months and then discontinued the drug observation. If the urinary tract infection recurs, the treatment will be restarted. The course of treatment is 1 to 2 years. Those who are allergic to sulfamethoxazole can use trimethoprim (trimethoprim). Quinolone drugs such as ofloxacin (floxacin) can also be used.

2. Prevention and treatment of dehydration

Get plenty of water. Because this type of patients cannot excrete concentrated urine, it is easy to dehydrate clinically. In addition, drinking more water can reduce the hypertonic state of the renal medulla, which is conducive to controlling infection.

Reflux nephropathy prognosis

Studies have shown that the prognosis of reflux nephropathy has important relationships with proteinuria, focal segmental glomerulosclerosis, and progressive renal dysfunction. The degree of proteinuria is significantly related to the presence and absence of glomerular injury and glomerular injury. Progressive glomerulosclerosis is the most important determinant of chronic renal failure in reflux nephropathy.

Reflux nephropathy prevention

Reflux nephropathy is a disease caused by a variety of causes. Prevention should start with prevention and treatment of primary diseases. For diseases that are likely to cause reflux, they must be carefully examined, diagnosed, and actively treated symptomatically to prevent the occurrence and progressive exacerbation of reflux nephropathy .