Pediatric posterior urethral valve
Introduction
Introduction to pediatric posterior urethral valve The posterior urethral valve (posteriorurethralvalve) is the most common disease in congenital lower urinary tract obstruction in male children, often caused by hydronephrosis. With the widespread use of prenatal ultrasound, the discovery rate of neonatal hydronephrosis has gradually increased, and early detection of posterior urethral valve has become possible. basic knowledge Probability ratio: Susceptible people: infants and young children Mode of infection: non-infectious Complications: urinary tract infections sepsis
Cause
Post-pediatric urethral valve disease
(1) Causes of the disease
There are two types of urethral valve: anterior urethral valve and posterior urethral valve. The anterior urethral valve is often located at the junction of penis and scrotum. There are two mucosal flaps protruding into the urethra. The middle is a fissure, which is shaped like a vocal cord and affects urination.
1. Classification
The posterior urethral valve is generally divided into 3 types: Type I: Type I is the most common, the valve starts from the distal end of the fine sputum, and stops at the urethra. The valve is generally two, which are excised and excreted separately from the urethra. The posterior wall and the side wall are connected, and there is a crack in the middle. Some of the valves are fused to each other at the distal end of the spermatic tract, and then divided into two, stopping at the side wall of the urethra; some have only one valve, and one valve does not cause the urethra. Obstruction, there are more than 2 valves, and some from the middle of the fine, are all type I, type II: the valve from the proximal end of the fine, upward and outward, stop at the bladder neck, It is currently believed that this type does not exist clinically. These valvular substances are caused by superficial muscle hypertrophy from the ureteral orifice to the fine sputum, which is secondary to increased urinary resistance, in mechanical and functional obstruction. Such as neurogenic bladder, detrusor-sphincter synergy occurs, type III: the valve in the distal end of the membranous urethra, the diaphragm, the center of the pinhole-sized small hole, like the iris, urinating When the long elastic mucosal folds can be prolapsed into the urethra A typical bag-shaped valve into the wind, about 5% of posterior urethral valves, in our case, only to see the case in point.
Type IV: In addition to the aforementioned Type 3, Stephens reported in 1983 that there is a type 4 posterior urethral valve in the Piriform Abdominal Syndrome, that is, due to relaxation, unsupported prostate mucosal folds fold into the urethra to form a relative outflow obstruction. Not yet recognized, there are also three types of posterior urethral valves.
2. Causes
The true etiology of type I posterior urethral valve is not well understood, but it is generally believed to be due to the abnormal insertion of the middle kidney tube into the original cloaca. The normal middle kidney tube enters the cloaca from the side, and the anorectal tube and urogenital sinus are separated when the cloaca is folded. At the time, the middle renal tube opening is displaced posteriorly and finally opened at the fine sputum; in the type I posterior urethral valve, the renal tube enters the cloaca with a more anterior position, and when it is folded inside, the middle kidney tube is blocked and is in the midline. The anterior fusion forms a valve, and the formation of the type III posterior urethral valve is related to the incomplete absorption of the urinary tract membrane, which may be different depending on the elasticity of the membrane and the position of the pore.
(two) pathogenesis
The posterior urethral valve is formed in the early stage of the embryo, which can cause dysplasia and dysfunction of the urinary system and other systems. Fetal urine is the main source of amniotic fluid in the middle and late pregnancy. The fetus of the posterior urethral valve is less due to urethral obstruction and less urination, resulting in decreased amniotic fluid. Too little amniotic fluid hinders the normal activity of the fetal thorax and the expansion of the lung in the uterus, causing lung dysplasia. Children often have difficulty breathing, cyanosis, respiratory distress syndrome, pneumothorax and mediastinal emphysema, which can die from respiratory failure. Due to urinary tract obstruction, the inflation pressure is increased, the ureter anti-reflux mechanism is imbalanced, the vesicoureteral reflux and the kidney, the ureter is expanded, and the pressure in the renal medulla is increased, resulting in abnormal renal development and increased upper urinary tract pressure. It can damage the collecting duct system of the kidney, resulting in renal tubular dysfunction, that is, acquired renal polyuria or renal diabetes, increased urine output, which in turn increases ureteral dilatation, and also increases bladder capacity, forming a vicious circle. The bladder of the urethral valve is to overcome the resistance of urination, the detrusor contraction is hypertrophy, and the collagen fibers are calm, and the bladder is reversed. Detrusor function decline, resulting in bladder dysfunction.
Prevention
Post-pediatric urethral valve prevention
At present, there is no special prevention method, actively prevent and treat urinary tract infections, actively prevent complications, and actively treat to improve the prognosis. Precautionary measures should be carried out from pre-pregnancy to prenatal, pre-marital physical examination mainly includes serological examination (such as hepatitis B virus, treponema pallidum, HIV), reproductive system examination (such as screening for cervical inflammation), general physical examination (such as blood pressure, electrocardiogram) and inquiry. Family history of the disease, personal medical history, etc., do a good job in genetic disease counseling, pregnant women to avoid harmful factors, including away from smoke, alcohol, drugs, radiation, pesticides, noise, volatile harmful gases, toxic and harmful heavy metals, etc. during pregnancy Prenatal care needs to be systematically screened for birth defects, including regular ultrasound examinations, serological screening, etc., if necessary, for chromosome examinations. Once an abnormal result occurs, it is necessary to determine whether or not to terminate the pregnancy; Internal safety; whether there are sequelae after birth, whether it can be treated, how to prognose, etc., take practical measures for diagnosis and treatment, the fetus of the posterior urethral valve first manifests as hydronephrosis, which is often characterized by bilateral kidney and ureteral hydrops. The bladder wall is thickened and the amniotic fluid volume is reduced. In the fetus, the decrease in amniotic fluid volume is the presence of the lower urinary tract. The important signal of resistance, the problem of decompression of intrauterine bladder fistula in the fetus of posterior urethral valve, is currently controversial, its effect on mother and fetus, the effect it can achieve, and the occurrence of complications. The situation is still under observation.
Complication
Post-pediatric urethral valve complications Complications, urinary tract infection, sepsis
Bladder ureteral reflux, ureteral hydronephrosis, hydronephrosis, chronic renal failure, acquired renal polyuria or renal diabetes, complicated with urinary tract infections and sepsis; may be combined with other malformations, such as sputum hypertrophy, cryptorchidism, Abdominal wall defects, etc.
Symptom
Post-uterine urethral valve symptoms Common symptoms Urinary tract infections, urinary urination, urinary incontinence, acute urinary retention, dehydration, ascites, dyspnea
Clinical manifestations vary with age and degree of posterior urethral valve obstruction.
Neonatal period
There may be urination, crying and urine dripping symptoms, and even acute urinary retention. In the lower abdomen, the inflated bladder is often touched and the wall is thick. It can also cause difficulty in breathing, cyanosis, etc. due to lung dysplasia. Some children may have urinary ascites. Urine can ooze from the renal parenchyma or the renal sinus and penetrate into the abdominal cavity through the permeable peritoneum. Urine ascites can cause imbalance of water and electrolyte balance, and even life-threatening, but the urine is diverted to the abdominal cavity, reducing the pressure on the kidneys, and the peritoneum can absorb ascites, so it is beneficial to the prognosis of sick children. Newborns with severe urinary tract obstruction in the posterior urethral valve may have severe urinary tract infections, uremia, dehydration, and electrolyte imbalance.
2. Infancy
Children who are in infancy may have growth retardation and urinary tract infections, or even sepsis. Due to vomiting and malnutrition, it can be suspected of digestive diseases.
3. School age
Mainly manifested as prolonged urination time, fine urinary line, urination and labor, often with residual urine leading to urinary incontinence and enuresis. Ultrasound should be performed on men with abnormal urination, dysuria and repeated urinary tract infections. If there is hydronephrosis, bladder dilatation and trabecular chamber, the posterior urethra ultrasound can be performed through the perineum. Experienced physicians can find the valve. Considering the posterior urethral valve should be performed with urinary bladder urethrography (VCUG), VCUG can be seen in the prostatic urethra, the distal urethra is very thin, the bladder edge is not smooth, there are trabecular chambers, and there are different degrees of vesicoureteral flow. The fetus of the posterior urethral valve first manifests as hydronephrosis, but it has its characteristics, often bilateral hydronephrosis of the kidney and ureter, thickening of the bladder wall, and decreased amniotic fluid volume. In the fetus, a decrease in amniotic fluid volume is an important sign of obstruction in the lower urinary tract. For newborns with bilateral hydronephrosis in the fetal period, ultrasound examination and VCUG should be performed after birth to confirm the posterior urethral valve as early as possible.
Examine
Pediatric urethral valve examination
Laboratory test
In the case of infection, urine tests for white blood cells, pus cells, urine drainage after neonatal birth and anti-inflammatory treatment 5 to 7 days after the serum creatinine level can be used as a reference value for children with renal function indicators, but the blood of newborn babies The creatinine value reflects the level of renal function of the mother. In addition to the elevated creatinine level, the renal concentrating function is reduced, and the urine specific gravity is low and fixed. This is related to the high pressure caused by obstruction leading to the development and dysfunction of the distal part of the nephron. Dysfunction leads to two consequences:
1 The kidney's ability to regulate water is reduced, so that children with water loss (such as vomiting, diarrhea, high fever, etc.) are more prone to dehydration and electrolyte imbalance;
2 high urine flow leads to further ureter and bladder dysfunction, some blood urea nitrogen, creatinine increased, often low potassium, hyponatremia, carbon dioxide binding decreased.
Radionuclide kidney
Renal ultrasonography and intravenous urography can be found in bilateral hydronephrosis, the degree of water accumulation on both sides can be inconsistent, can also be unilateral, when renal function is lost, intravenous pyelography can not be developed, but the renal pelvis is normal, It is not completely ruled out that the urethral valve, bilateral kidney, ureteral hydrops, thick-walled bladder and dilated posterior urethra suggest a posterior urethral valve. Ultrasound shows that the renal cortex is clearly defined as a good prognosis. Hydronephrosis and persistent bladder filling are suspected of this disease, and ultrasound examination or bladder urethrography is performed 24 hours after birth. Recently, fetal cystoscopy has been reported. Radionuclide kidney map can be used to observe total kidney and kidney function. The newborn must be delayed until 1 month after birth to facilitate the development of the kidney, and the initial renal examination can be used as an evaluation index for the treatment effect.
2. Urethral angiography
Urethral angiography is very helpful for diagnosis, and urinary bladder urethrography is more valuable. Due to the wide application of this type of examination, the diagnosis rate of this disease is increasing year by year. The most common type I can be seen that the valve is very thin. A layer of filling defect, the bladder can be seen in the formation of trabeculae, the defect of the proximal posterior urethra dilatation, the neck muscles protruding into, seemingly narrow, the posterior urethra is extremely dilated, connected with the bladder neck, shaped like a gourd, and the anterior urethra Fine or no urine, type II and type III (there is a septum at the proximal end of the sputum), the posterior urethra does not dilate, and the type III of the septum has a septum at the proximal end. When retrograde urethrography is performed, the contrast agent is applied to the diaphragm. The position is blocked, the contrast agent stays in the posterior urethra, and the diaphragm is bulged into the bladder, which is spherical, retrograde urethrography and urinary bladder urethrography contrast examination, the diagnosis value is greater.
3. Urethoscopy
The valve can be seen directly, suitable for all patients, and can exclude other diseases that coexist, such as repeated urethra, giant urethra, anterior urethral diverticulum and cavity spinal bulging. In addition, we have two patients with urinary retention who are on the pubic bone. In the case of bladder stoma, the urethra probe is used to examine the posterior urethra, one through the bladder neck and the other from the urethral opening into the posterior urethra. The two meet at the valve, but the two probes can touch each other. The feeling of the diaphragm, posterior urethral urethra confirmed as the posterior urethral valve, and thus probe detection, can also be used as a diagnostic method.
4. Urodynamic examination
Urine flow rate examination is of great value in the diagnosis of lower bladder urinary tract obstruction, but it is limited due to the lack of cooperation between infants and young children. The bladder pressure measurement shows decompensated bladder, residual residual urine, large bladder capacity, low compliance bladder, such as Ureteral re-invasion can not be performed in bladder hypertension caused by low bladder compliance. The urethral pressure map measurement has great significance for localization diagnosis. The normal urinary tract pressure map is slope-shaped, and the congenital posterior urethral valve can be used. Sudden pressure rise at the valve is a saddle curve, pressure / flow rate check, bladder urethra - pressure - flow rate test diagnosis is the most accurate, but often because children do not cooperate can not be carried out, upper urinary tract dynamics test also has a certain meaning, When the upper urinary tract water does not relieve after the treatment of the posterior urinary tract, this examination is necessary to determine the cause of water accumulation. The percutaneous urinary tract pressure-flow rate test (Whitaker test) helps to identify the mechanical or dynamic of the upper urinary tract. Sexual obstruction, studies have shown that the true incidence of bladder ureter junction obstruction is extremely low.
Diagnosis
Diagnosis and diagnosis of posterior urethral valve in children
diagnosis
For males with abnormal urination, dysuria and repeated urinary tract infections, ultrasound examination should be performed. If there is hydronephrosis, bladder dilatation and trabecular chamber, the posterior urethra ultrasound can be performed through the perineum. Experienced physicians can find the valve, considering the posterior urethral valve should be urinary bladder urethrography (VCUG), VCUG can be seen in the prostate urethral dilatation, the distal urethra is very thin, the bladder edge is not smooth, there is trabecular chamber formation, There are different degrees of vesicoureteral reflux, the fetus of the posterior urethral valve first manifests as hydronephrosis, but it has its characteristics, often bilateral renal and ureteral hydrops, thickened bladder wall, decreased amniotic fluid, in the fetus, amniotic fluid The reduction of volume is an important signal for the obstruction of the lower urinary tract. For newborns with bilateral hydronephrosis in the fetal period, ultrasound examination and VCUG should be performed after birth to confirm the posterior urethral valve as early as possible.
Differential diagnosis
The urethral valve should be differentiated from congenital bladder neck obstruction, congenital hypertrophy, neurogenic bladder dysfunction, chronic nephritis and polycystic kidney disease. Adult posterior urethral valve should be differentiated from benign prostatic hyperplasia due to posterior urethra The valve can cause the fusiform urethra of the prostate to expand, and the bladder neck bulges, creating the illusion of bladder neck hyperplasia, resulting in unnecessary surgery.
