Hypospadias is a common congenital malformation of the urinary system in children, with an incidence of about 1/300. It is due to the underdevelopment of the anterior urethra in the embryonic period so that the opening of the urethra fails to reach its normal position, which is manifested by the anomalous opening of the external urethra, the lower curvature of the penis, and the abnormal distribution of the prepuce. Etiology and pathogenesis] The development of normal external genitalia is completed in the 12th week of embryo. In the 6th week of the embryo, the urogenital sinus appears ventrally as a genital nodule, and soon a genital protuberance occurs on each side of the genital nodule. The urogenital groove is located on the caudal midline of the genital nodule, flanked by the urogenital folds, and the urogenital sinus membrane is located at the base of the urogenital groove. After the 7th or 8th week, the external genitalia begin to differentiate sexually. In the presence of dihydrotestosterone, the genital nodes develop into the penis, the lower part of the urogenital sinus extends into the penis and opens into the urethral groove, the urogenital folds on both sides fuse from proximal to distal, and the external orifice of the urethra moves to the tip of the head of the penis. At week 12, the skin at the head of the penis is reflexed to form the penile foreskin. In the embryonic period, hypospadias is formed when the urethral folds are incompletely fused for any reason. The etiology of hypospadias is related to the following factors: 1, genetic factors Hypospadias has a clear family tendency, and the disease is polygenic. The incidence of the general population is 1‰ ~ 8‰, and the incidence of male relatives with preexisting conditions is 2.2%, Bauer et al. reported that 8% of the patients’ fathers and 14% of the patients’ brothers also have urethral hypospadias. 2.Hormonal abnormalities Chorionic gonadotropin (HCG) stimulates the testicular interstitial cells (Leydig cells) to produce a peak in the eighth week of pregnancy, and reaches its peak in the twelfth week. Testosterone is converted to dihydrotestosterone (DTH) by the enzyme 5α reductase. The development of external genitalia is regulated by dihydrotestosterone. Any cause of insufficient or delayed production of testosterone or an abnormality in the conversion of testosterone to dihydrotestosterone can lead to reproductive malformations. Hormonal abnormalities affecting urogenital development may be present during the embryonic period in the following areas: (1) insufficient production of HCG, (2) insensitivity of the fetal testes to HCG, (3) insufficient or delayed testosterone production with a peak later than 12 weeks, (4) deficiency of the enzyme 5 alpha reductase and abnormal conversion of testosterone, and (5) abnormalities of the mother’s pre-pregnancy hormone intake. 3, Androgen receptor abnormalities Mutations in the androgen receptor (AR) gene are one of the causes of hypospadias. Literature reported that patients with hypospadias had insufficient expression of AR and defective binding of AR to DTH in the foreskin, while Brown et al. reported that mutations in the gene encoding AR, which is located on the long arm of the X chromosome and inherited by X-linked recessive inheritance, caused abnormalities in the expression of AR. Lubahn reported that single-stranded DNA bands of exon 8 of the androgen receptor gene had a dynamic dislocation and abnormal expression of the androgen receptor. 4. Epidermal growth factor and its receptor abnormalities Gupta et al. reported that epidermal growth factor (EGF) affects the development of the male genital tract, but the expression of EGF and epidermal growth factor receptor (EGFR) in the foreskin of children with hypospadias is insufficient. Typical hypospadias has three features: ectopic urethral orifice, penile recurvature, and abnormal foreskin distribution. 1, ectopic urethral orifice The urethral orifice can be ectopic opening from the normal urethral orifice proximal to the perineal urethra in any part of the urethra. The urethral orifice has a mild narrowing of the distal end of a mucous membrane-like shallow groove, partially covered with a film. The child often urinates in the squatting position, and the urethral opening is more pronounced the more proximal it is to the body of the penis. According to the location of the urethral opening, there are four types of hypospadias: Ⅰ°: penile head and coronal sulcus; Ⅱ°: penile body; Ⅲ° penile scrotum; Ⅳ° perineum. In order to facilitate the estimation of the surgical effect, Barcat according to the correction of the recession of the urethra after the location of the recession of the urethra is divided into: anterior type, including the head of the penis type, coronal groove type, penile body anterior type, accounting for 65%; intermediate type accounted for 15%; the posterior type, including the posterior type of the penile body, penile scrotum, scrotum, perineum type, accounting for 20%. 2, penile recumbency Hypospadias mostly exists in the penis to the ventral side of the bend, the reason is mainly the urethral plate fibrous tissue hyperplasia at the distal urethral orifice, the lack of subcutaneous tissue in all layers of the ventral side of the penile body, and asymmetric dorsal and ventral sides of the penile sponge body. According to the angle between the head of the penis and the longitudinal axis of the penile body will be divided into mild penile recurvature: less than 15 °; moderate: 15 ° ~ 35 °; severe: more than 35 °. 3.Abnormal distribution of foreskin Hypospadias manifests itself as a cap-like accumulation of foreskin on the dorsal side of the penis, a V-shaped defect in the ventral foreskin, and absence of the foreskin tie. The most common combined malformations are inguinal hernia and cryptorchidism, each accounting for 9%. Severe hypospadias is sometimes combined with prostatic bursa, and the incidence of perineal and penoscrotal hypospadias is reported to be 10%-15%, which opens at the back of the urethra in the prostate department and sometimes causes infection and stone, and the possibility of prostatic bursa should be considered when inserting a catheter is difficult. The incidence of concomitant upper urinary tract deformity varies from 1% to 3%. Some cases are combined with penile scrotum transposition, penile torsion, small penis, duplicate urethra and so on. Treatment] There are many treatment methods for urethral hypospadias, but whatever method should reach the currently recognized cure standard: (1) penile recurvature is completely corrected; (2) urethral orifice is located in the positive position of the head of the penis; (3) penile appearance is satisfactory, close to normal, able to stand and urinate, and able to carry out a normal sex life after adulthood. 1.Surgical treatment includes staged plasty and one-stage urethroplasty. Staging plasty refers to the urethroplasty performed 6 months to 1 year after the correction of penile recurvature in one stage. One-stage urethroplasty includes correction of penile recurvature, urethroplasty, urethral orifice and penile head molding, penile ventral trauma coverage and scrotal molding. Principles of selection of surgical methods: (1) the distal penile hypospadias commonly used surgical procedures: MAGPI (urethral anterior displacement of the penile head plastic surgery), Mathieu surgery, Mastarde surgery, Onlay transverse island flap urethroplasty. (2) For penile body type hypospadias: Duckett operation (transverse island flap urethroplasty), scrotal suture island flap urethroplasty, Tip (urethral plate median incision) urethroplasty. (3) For the proximal type of penile body (including penile scrotum type, scrotum type and perineum type), the commonly used surgical procedures for hypospadias: scrotal suture island flap urethroplasty, Duckett’s operation, Duplay’s operation plus transverse island flap urethroplasty, and so on. 2, common complications after urethral hypospadias and treatment (1) urethral fistula is the most common complication after urethroplasty, the incidence rate of 15% to 30%, even if the operator is skilled, but also in 5% to 10%, the main reason is to do urethroplasty material blood supply is poor, local tissue ischemia, necrosis, infection. Urethral stenosis, poor urine drainage makes the incision tension increase and split. Small urethral fistula has the possibility of self-healing, regular postoperative urethral dilatation to prevent urethral stenosis can reduce the pressure during urination to help the healing of urethral fistula. Six months after the operation, the feasibility of urinary fistula repair. For the pinhole size of the urinary fistula, ligation method can be used; incision and suture method and skin flap to cover the fistula method is suitable for the diameter of less than 1.0cm of small urinary fistula; diameter greater than 1.0cm large urinary fistula, should be based on the location of the urinary fistula, the size of the fistula, the local skin conditions, the penile skin can be used to adequate flip-flap (tipping bucket flap), duckett, etc., the penis skin is not enough can be used. Denis-Browne, Duplay, Thiersch and other methods. (2) Urethral stenosis Mostly occurs at the urethra and anastomosis of the penile head segment. Urethral dilatation can be used for strictures within 3 months after surgery, and surgery is needed if it is ineffective. Urethral stenosis in the head section of the penis can be improved by dilatation, otherwise, the narrowed urethra can be cut and urethroplasty can be performed after 6 months. Proximal anastomotic stricture urethral dilatation is ineffective, then the local urethrostomy six months and then repair, anastomosis beveled anastomosis, excision of no urethral spongiosum section of the urethra, anastomosis fixed in the spongiosum to avoid torsion can reduce the anastomotic stricture. Formed urethral stenosis due to poor urethral blood flow caused by tissue necrosis, contracture or formed urethra twisted, rarely cured by urethral dilatation, most need to cut the stenotic segment, six months after the urethroplasty. (3) Urethral diverticulum The cause may be secondary to urethral stenosis, large caliber of formed urethra, and little tissue around formed urethra. Smaller urethral dilatation can be improved after the stenosis is lifted, and large urethral dilatation should be eliminated first and then diverticulotomy and urethroplasty should be performed. 3, the common problems of urethral hypospadias (1) age of surgery In the past, the staged age of surgery in the age of 2 ~ 5 years, before puberty to complete the treatment. Nowadays, early (2~4 years old) one-stage surgery is preferred to reduce the psychological burden of the children, and the improvement of surgical instruments and surgical skills make early surgery possible. before the age of 4, the growth of penis is very small, and the degree of penile development should not be an important factor in the selection of the age of surgery for hypospadias. (2) Surgical instruments and sutures Plastic surgical instruments are necessary. Suture mostly choose 5-0, 6-0, 7-0 absorbable thread, commonly used in China Dexon, Vicryl, Ethicon, etc. Suture skin can be used intestinal thread, about 14 days of absorption without having to remove the thread. Needle electrocoagulation hemostasis, can reduce bleeding. (3) Dressing Multi-layer fishnet gauze evenly and gently packed pressure bandage to prevent premature shedding of the dressing, otherwise it is easy to swelling, subcutaneous bleeding affect the surgical effect. Open the dressing 4 to 5 days after surgery to observe the wound, and it is necessary to continue bandaging until 7 days after surgery. In recent years self-adhesive elastic bandage dressing gradually increased. (4) Urine diversion Urethroplasty needs to drain urine, the methods are: suprapubic cystostomy or transurethral ureteral drainage. Pediatric Surgery Department of our hospital is currently using high-quality silicone urethral drainage, reducing the trauma caused by suprapubic cystostomy, postoperative urethral drainage needs to be kept smooth. (5) Postoperative catheterization time The catheter is usually removed about 10 days after surgery, and the catheter needs to be intermittently clamped before removal. (6) Postoperative follow-up 1 week after discharge, you can return to the hospital to check the urethral orifice and anastomosis, observe the urinary discharge; 4 weeks later, check again, if the urinary discharge is smooth, the interval of half a year, 1 year follow-up; if there is a narrowing of the urethra dilatation can be carried out at intervals of 1 to 2 weeks. Repeated dilatation still exists stenosis is feasible urethroplasty. Severe urethral stenosis, should not be forced to dilate, feasible urethrostomy, 3 ~ 6 months after the urethroplasty. (7) Surgical efficacy of the literature reported that the cure rate of various types of surgery ranges from 45% to 95%. The pediatric surgery department of our hospital has completed more than 300 cases of hypospadias in the past 5 years, and the cure rate of the first stage reaches more than 90%.