I. What is a urethral valve? Urethral valves are the most common cause of urethral obstruction in infants and newborns. The flap is a mucosal fold that resembles a very thin membrane. During urination, the valve can cause varying degrees of obstruction. This disease occurs only in men, and the flap is usually located at the distal end of the prostatic urethra, and is divided into anterior urethral flap and posterior urethral flap depending on the location of the flap, with posterior urethral flap being common. The small children of the urethral valve can have symptoms of urinary obstruction of no present degree. Pulsatile voiding is often seen, with weak urine lines, close range, interrupted urination, drenching, urinary tract infection and sepsis. Severe obstruction can cause hydronephrosis, with palpable masses in the abdomen and a distended bladder in the lower abdomen. In a few patients, hydronephrosis may be palpated on both sides of the ribbed abdomen. Most children are born with developmental delay, and physical examination may not reveal anything other than signs of chronic disease. Second, how to treat urethral valve? The main purpose of treatment is to remove the valve and protect the kidney function. The principle of treatment is to correct the water-electrolyte balance, control the infection, drainage and release the lower urinary tract obstruction. The best way to protect the kidney and bladder function is early detection, prenatal ultrasound examination of the fetus, careful physical examination of the newborn, observation of urination and urinalysis. The prognosis for children with azotemia and prolonged urinary tract infections is poor, even if the obstruction has been relieved. The choice of surgical method and the route to be followed depends on the degree of obstruction and the health status of the child. For mild or moderate obstruction with mild azotemia, transurethral electrocautery flap can be used with satisfactory results. Due to the current application of electrocautery for infant cystourethroscopy, electrocautery of the urethral valve can be performed in the neonatal period. Children with severe obstruction causing varying degrees of hydronephrosis, urinary sepsis and azotemia should be treated with antimicrobial agents, indwelling catheters and correction of electrolyte balance disorders. Children with vesicoureteral reflux and renal dysplasia should undergo cystostomy or cystostomy, which has the advantage of not carrying a fistula and reduces the chance of bladder irritation and secondary infection. Most children with severe hydronephrosis have unsatisfactory results with cystostomy and valvulotomy alone because of ureteral dilatation and hypertrophy of the bladder triangle due to frequent infections, resulting in obstruction of the ureteric-vesical junction. For these patients, ureteral skin stoma or nephrostomy is required to achieve protection of renal function and reduce or eliminate hydronephrosis, and then flap resection and ureteral reconstruction can be performed after renal function improves. The duration of urinary diversion should be as short as possible; prolonged bladder and upper urinary tract diversion can cause permanent bladder contracture. Approximately 50% of children with urethral valves are associated with vesicoureteral reflux, and the prognosis for bilateral reflux is often poor. After the obstruction is removed, antimicrobial agents are needed to prevent recurrence of urinary sepsis and urinary tract infections. 1/3 of patients with reflux disappear spontaneously, while 1/3 of patients with reflux do not improve after surgery and develop recurrent urinary tract infections, requiring anti-reflux surgery, the most used being Conen vesicoureteral reimplantation.