Congenital obstruction of the ureteropelvic junction in children

Brief introduction of congenital renal pelvis and ureteral junction obstruction in children Congenitalureteropelvic junction obstruction (UPJO) is one of the most common urinary tract malformations in children, which can lead to hydronephrosis. There are three types of obstruction of the ureteropelvic junction: endogenous obstruction, exogenous obstruction and secondary obstruction. Due to the obstruction of the joint, the urine in the renal pelvis cannot be unobstructed and flows into the ureter in time, resulting in continuous and progressive expansion of the renal collecting system, which further destroys the emptying capacity of the renal pelvis. basic knowledge Sickness ratio: 0.0001% Susceptible people: children Mode of infection: non-infectious Complications: urinary tract infection, hydronephrosis, hypertension

Pediatric congenital pyelone ureteral junction obstruction etiology

(1) Causes of the disease

Although many studies have been carried out on embryology, histology and anatomy, the exact cause of UPJO remains unclear. At present, it is believed that the development of the ureteropelvic junction is stagnant or the ureter has a substantial and re-cavitation in the fetal period. The process, such as incomplete re-cavity, results in endogenous obstruction of the ureteropelvic junction.

Endogenous obstruction

(1) Circumferential muscle development at the junction of the renal pelvis and ureter: In 1958, Murnaghan discovered that the muscle development of the ureteropelvic junction was paused, which destroyed the funnel-like structure of the joint, resulting in poor drainage of the urine, and hydronephrosis. Aggravation of the destruction of the funnel-like structure.

(2) Excessive collagen fiber content: Nutley in 1968, Hanna et al. in 1976. It was found in the electron microscope that the arrangement of muscle cells in UPJO was normal, but the content of collagen fibers was greatly exceeded, which led to an increase in the spacing between muscle fibers. Many muscle cells even shrink, causing the muscle contraction function of the ureteropelvic junction to be broken, and the urine in the renal pelvis cannot be emptied.

(3) ureteral valve: ureter congenital mucosal fold is a kind of ureteral valve, which is a very common phenomenon in the upper ureter of the fetus after 4 months. This mucosal fold can even extend to the neonatal period. It is said that mucosal folds do not form obstruction and can disappear with growth and development, and are rare in older children or adults.

(4) Other causes: Other causes of endogenous obstruction of the ureteropelvic junction include:

1 valvular mucosal folds.

2 The persistence of fetal ureteral twisting and folding.

3 ureteral initial polyps: polyps are generally small, mostly located in the ureteropelvic junction or upper ureter, can form incomplete obstruction, children may have hematuria, or paroxysmal abdominal pain, the rate found in UPJO increased Potential, from the follow-up point of view, there is little recurrence after surgery.

2. Exogenous obstruction The most common exogenous obstruction is the vagus or accessory vasculature that governs the inferior pole cortex. The vasculature often passes through the ureteral ureteral junction or the upper end of the ureter. The incidence of UPJO caused by blood vessels is between 15% and 52%. It is more common in adults. There are few children. The vagus blood vessels make the ureter fold into an angle. When the renal pelvis is full, the ureteral junction and blood vessels can pass through the ureter. Obstruction is formed, and the ureter pulled by the vagus vein can form a fascial adhesion between the ureter and the renal pelvis. Long-term compression of the ureter can cause ischemia, fibrosis and stenosis, so even if some people think that the adhesion is loose, the free blood vessel can be The UPJO was lifted, but the ureter that obstructed the lesion was still removed.

3. Secondary obstruction UPJO can be caused by severe ureteral reflux, accounting for about 10% of the total. Reflux can cause distortion of the ureter, thickening and elongation, and the position of the ureteropelvic junction is relatively fixed. Folding, resulting in obstruction, the same principle UPJO is also caused by obstruction of the ureteral junction of the bladder, the incidence of contralateral renal malformation in children with UPJO is quite high, including other congenital malformations, the incidence of contralateral UPJO is reported as 10% ~40%, other can be renal dysplasia, polycystic kidney disease, etc., UPJO can also occur in the upper kidney or lower half of the kidney, can also occur in horseshoe kidney or ectopic kidney, UPJO patients with mild ureter The incidence of reflux can reach about 40%, which is more likely to be caused by urinary tract infections and can disappear on its own. The incidence of UPJO in Vater syndrome is 21%.

(two) pathogenesis

Urinary tract obstruction caused by many lesions inside and outside the urinary system eventually leads to increased intra-renal pressure, impaired renal pelvis and renal pelvis discharge, prolonged urinary retention in the renal pelvis, dilated renal pelvis, and gradually increased intra-arterial pressure. Tube expansion affects the secretion of urine, while oppressing nearby blood vessels causes anemia atrophy of the renal parenchyma, due to dilated renal pelvis and renal pelvis, renal parenchymal atrophy, renal dysfunction, called hydronephrosis, hydronephrosis in the progression of the disease Divided into:

1 The renal pelvis enlarges and the renal pelvis wall becomes thinner.

2 Kidney papillary atrophy (the pyelography showed that the cup-shaped renal pelvis gradually flattened and finally protruded to the outer layer).

3 The renal parenchyma is progressively atrophied and thinned. When the renal pelvis is intrarenal, the renal parenchyma atrophy occurs earlier and more severely. Urinary obstruction, when the urine is blocked from the renal pelvis and renal pelvis, some of the fluid can enter the lymphatic vessels and veins. (renal pharyngeal reflux, renal pelvic venous reflux), this will slightly reduce the pressure in the renal pelvis and renal tubules, there is still the ability to continue to secrete urine, when the ureter is blocked, uremia often occurs within 3 days, such as obstruction After 8 days of elimination, renal function can still be recovered, and hydronephrosis caused by partial obstruction or intermittent obstruction often reaches a large volume.

Pediatric congenital pyelone ureteral junction obstruction prevention

At present, the cause is still unclear, and there are no definite preventive measures. After the diagnosis is clear, the obstruction should be lifted as soon as possible and the urinary tract infection should be actively prevented.

Pediatric congenital ureteropelvic junction obstruction complications Complications, urinary tract infection, hydronephrosis, hypertension

Often complicated by repeated urinary tract infections, accompanied by hydronephrosis, high blood pressure and growth retardation.

Pediatric congenital pelvis and ureteral junction obstruction symptoms common symptoms nausea and abdominal pain infant feeding difficulties hypertension hematuria fetal growth retardation

The urinary tract obstruction caused by UPJO is incomplete, the disease progresses slowly, and there is no clear symptom. Sometimes, when the urine volume is high, abdominal pain occurs due to poor drainage caused by renal pelvic contraction, but it is difficult to point out the specific part, which may be accompanied by nausea and vomiting. In neonates or infants, UPJO can cause hydronephrosis to be an asymptomatic abdominal mass, which is accidentally discovered during physical examination. In the age of no ultrasound, about 50% of cases are found, with pregnancy. Conventional use of ultrasound, in recent years, many UPJO cases of hydronephrosis can be diagnosed in the fetal period, other performances include growth retardation, feeding difficulties, repeated urinary tract infections and hematuria, etc. After the period, the incidence of urinary tract infections can reach 30%. In the past 30 years, 304 cases of UPJO caused hydronephrosis, and only 6 cases with urinary tract infection as the first symptom, in the UPJO caused by vagus blood vessels.

Due to the interstitial obstruction, the child has paroxysmal abdominal pain, sometimes accompanied by vomiting. Hematuria is often caused by rupture of the renal pelvis mucosal blood vessels. For example, elderly children in puberty often have abdominal pain after drinking plenty of water. Older patients can High blood pressure occurs because the expansion of the collecting system, renal blood flow, renal functional ischemia, mediated by renin, angiotensin, children with hydronephrosis in the fetal diagnosis, must be reviewed after birth The time is best after birth and several weeks after birth (usually 4 weeks). Within about 3 months after birth, the kidney is still developing, and the kidney cone and medulla are translucent and can produce kidney product. The illusion of water, it is necessary to check the B-ultrasound after birth. It is still difficult to estimate the degree of hydronephrosis in the fetus and newborn. According to the report, mild to moderate hydronephrosis Most children with 2cm can relieve themselves within 2 years. The isotope curve of this part of the child shows normal uptake of radionuclides, but excretion is significantly delayed. UPJO leads to laboratory tests for hydronephrosis. Characteristic change.

Pediatric congenital pelvis obstruction of ureteral junction obstruction

1. Urine routine examination Most of the children's urine routine is normal, when there is a urinary tract infection, there may be white blood cells; some patients with hematuria.

2. Blood routine examination can cause anemia when the kidney is damaged, red blood cell count is reduced, and hemoglobin is decreased.

3. Renal function test in children with general hydronephrosis, their renal function is in the normal range, unless it is very serious hydronephrosis with progressive renal failure, B-ultrasound can occur hydronephrosis, X-ray examination is the main diagnosis Methods, plain film and renal pelvic venography can understand the bilateral renal and ureteral conditions, and can be a nuclear map.

4. Ultrasonography is the most commonly used and most effective non-invasive examination method. It can be found that the renal pelvis and renal pelvis are separated and expanded, and the thickness of the renal cortex can be measured. Generally speaking, UPJO causes hydronephrosis and its ureteral caliber is basically normal. Ultrasound's judgment on the degree of hydronephrosis is not the most serious and significant water. The data does not reflect the severity of hydronephrosis and the actual state of renal function, but it is still the preferred method.

5. Excretory venous urography (IVU) showed dilated renal pelvis, dilated renal pelvis, ureteropelvic junction interruption, ureter not showing, 60% or 76% diatrizoate in children, newborn 8 ~ 10ml, <6 months 10 ~ 12ml, 6 ~ 12 months 12 ~ 15ml, and renal dysfunction, urea nitrogen up to 50mg / dl, instead of urinary closure, you can increase the dose up to 2.2ml / kg, add the same amount of glucose solution Rapid instillation, delayed filming, 60-120min photoparts of the whole urinary tract, then more visible renal pelvis, necessary fashion can use renal angiography to understand the obstruction site, but must be carried out on both sides, in order to avoid renal failure, we often use 76% diatrizoate 2.2ml / kg rapid intravenous push, the length of time the kidney begins to develop and the extent of contrast agent can reflect changes in kidney function, from the size of the kidney, the degree of renal pelvis, the degree of renal pelvis expansion and angiography The time of excretion of the agent can reflect the severity of the stagnant water. According to the severity of the stagnant water, the performance of the renal pelvis can be dulled from the lighter cup, flattened, and developed to a severe pelvic bulge, bulging, Fullness, sometimes contrast agent stays in expansion The renal pelvis does not enter the renal pelvis, such as a palette for painting, such as severely impaired kidney function, to delay the film, such as 240min, 360min, or even the next day to take pictures, in order to be able to determine the shape of the kidney as much as possible, but At present, when the kidney is severely developed due to severe water accumulation, MRU is often used instead. UPJO generally does not show ureter, but even the ureter at the distal end of the ureteropelvic junction can show serious obstruction at the ureteropelvic junction. Retrograde intubation of the ureter can confirm the whole process of the ureter. It is generally recommended that it be performed on the day of surgery. Urinary bladder urethrography is commonly used to diagnose lower urinary tract obstruction in children. Contrast agents can enter the bladder through three methods:

1 intravenous administration;

2 transurethral catheter into the bladder through the urethra, after injection, pull out the catheter to do urinary bladder urethra angiography, in the infant, you must press the bladder by hand to do urinary bladder urethra angiography;

3 through the suprapubic region puncture injection, any method should pay attention to the following points:

1 When urinating, multiple times of photography should be performed to observe the presence or absence of vesicoureteral reflux. Because vesicoureteral reflux is not seen at every examination, it is necessary to take oblique tablets;

2 Fill the bladder to its capacity to estimate the presence or absence of trabeculae, 5 to 13 years old bladder capacity (ml) = 146 + 6.1 × age, newborns are 75ml, large children up to 300ml;

3 pay attention to the problem of residual urine after emptying the bladder. The partial urethra is best to use oblique position. Its advantage is that the full length of the urethra can be seen when urinating, the amount of radiation in the oblique testicle is the least, and the bladder urethra should be normal. The filling defect, that is, the internal sphincter is more pronounced at the end of urination, and the normal phlegm can also have a filling defect.

6. Diuretic nephropathy Another important diagnostic method for hydronephrosis is the diuretic kidney map, which uses isotope techniques to measure blood flow to the kidneys, kidney function, tracer excretion, analysis, and generally kidney. The isotope uptake phase of the graph curve evaluates renal function. The excretory phase after furosemide injection can determine the severity of obstruction. For diuretic ureteropelvic junction obstruction, diuretic nephrogram is especially valuable. The presence of PUJO can only be found in abdominal pain, and the excretory urography can be completely normal when asymptomatic. The above situation is more common in hydronephrosis caused by vagus vascular compression, injection of furosemide, increased urine output, and renal pelvis emptying. Can not be completed in time, the symptoms of hydronephrosis can appear, of course, some sick children can have abdominal pain when doing diuretic kidney map, diuretic kidney map avoids the radiological hazard of conventional contrast methods, detection sensitive, even poorly functioning kidneys, If there is an isotope tracer that can be displayed, it can provide indicators of kidney function, so that the pre- and post-operative conditions are compared, according to the renal pelvis The rate of excretion can be estimated as the severity of obstruction. From our experience, postoperative renal reexamination is appropriate for 6 months after surgery. For example, diuretic renal examination should be performed 3 months ago. Oral edema affects urine drainage and is still a sign of mechanical obstruction.

7. Magnetic resonance urography (MRU) due to urinary tract obstruction caused by water accumulation, expansion, can be shown in the magnetic resonance T2 phase, especially in the case of renal dysfunction, IVU and isotope kidney map can not be displayed, through MRU can show the anatomy of the urinary tract, suggesting the location of the obstruction, magnetic resonance water imaging (MRU) can clearly indicate the location of upper urinary tract obstruction, urodynamics combined with X-ray examination, examination of some problems in lower urinary tract obstruction Very important, such as the compliance of the bladder and the coordination of the bladder mucosa and the urethral sphincter.

8. Urinary bladder urethra angiography in children with hydronephrosis must be done urinary bladder urethra angiography to rule out hydronephrosis caused by vesicoureteral reflux.

Diagnosis and differential diagnosis of congenital ureteropelvic junction obstruction in children

First of all, you should pay attention to the medical history. When the child complains of abdominal pain or low back pain, it must be differentiated from acute abdomen. If the abdominal mass is prominent, it must be combined with other retroperitoneal masses such as nephroblastoma, teratoma and neuroblast. Identification of tumors, such as bladder neck irritation symptoms such as frequent urination, urgency and dysuria, should pay attention to urination, such as small urination, urination, prolonged urination, urination after urination, such as mobile obstruction in the bladder Then the urine flow can be abruptly interrupted, anal examination should be done, attention should be paid to the presence or absence of pelvic tumors and stones, and anal sphincters. In addition to measuring the residual urine volume, the catheter can be excluded from the urinary tract stenosis. X-ray examination is to identify the cause. The main diagnostic methods, plain film visible kidney shadow contour, skeletal shadow, positive stones or calcification, intravenous pyelography can understand bilateral renal and ureteral conditions, urinary bladder urethrography is very common in the diagnosis of children with lower urinary tract obstruction, necessary fashion Renal puncture angiography is used to understand the obstruction site. B-mode ultrasonography can assist in the location of urinary tract obstruction. In addition to renal nucleus scanning, it can assist in the diagnosis of obstruction. Dissolving renal function, MRU can clearly show the location of upper urinary tract obstruction, urodynamics combined with X-ray examination, is very important for the detection of some problems in lower urinary tract obstruction, such as bladder compliance and bladder mucosa and urethra Coordination of sphincters, etc.

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