Hypospadias is the most common congenital malformation of the male genitourinary system, with an incidence of 1/300. It is thought to be recessively inherited, and if a couple has a child with hypospadias, there is a 10% chance that other children will be born. Normally, after the seventh week of embryonic life, the wall of the urethral folds gradually from the proximal end of the urethra towards the glans to form a tube called the urethra, a process that depends on the androgens secreted by the embryonic gonads and on the response of the embryonic urethral groove and folds to testosterone. Hypospadias is caused when the formation of a tube in the wall of the urethral folds is impaired. In addition, the interstitial tissue at the urethral opening does not develop, forming a fan-shaped fibrous cord that surrounds the external urethral opening and extends and embeds in the glans. Hypospadias can be divided into four types depending on the location of the urethral opening: 1. head of the penis, coronal groove type; 2. body of the penis type; 3. scrotum of the penis type; 4. perineum type. Since the degree of penile hypospadias is not proportional to the position of the urethral opening, some anterior hypospadias are combined with severe penile hypospadias. To facilitate the estimation of surgical results, Barcat’s method of staging the urethral orifice according to the location of the receding urethral orifice after correction of penile hypospadias is accepted by many. This staging includes 1. anterior type, where the corrected urethral orifice is located at the head of the penis or the coronal sulcus; 2. middle type, where the corrected urethral orifice is located at the body of the penis; 3. posterior type: where the corrected urethral orifice is located at the penile scrotal junction or perineum. Pathogenesis The urethral plate originates from the outward growth of the cloaca and the wall of the urogenital sinus. Urethral development begins at the embryonic 10 mm stage (approximately the 4th week of development), when the urethral plate is thought to be a thickening of the anterior wall of the internal cloaca. The urethral folds on the ventral side of the genital portion of the urogenital sinus on either side of the urethral plate develop to form the urethral grooves. These urethral folds are covered with epithelium, and the urethral grooves between the urethral folds are called primary urethral grooves. The secondary urethral grooves develop at the 35 mm stage of the embryo (approximately week 8) as a result of the breakdown of the top of the primary urethral grooves. The continuation of this process forms the final urethral groove. During the male fetal 50 mm stage (approximately week 1 1 of development), the number, size, and function of testicular mesenchymal cells (Leydig cells) increase and the urethral folds begin to fuse toward the membranous midline to form the urethra. After a similar process, the proximal portion of the urethra of the head of the penis soon forms and differentiates from the urethral plate (endodermal origin). The distal part of the urethra of the head of the penis is formed by a thin endogenous layer of surface epithelium (ectodermal origin) that grows distal to the urethral plate and becomes a compound squamous epithelium at the end of development. The “developmental arrest” theory is the most plausible explanation for hypospadias and explains the three typical features that accompany it: curvature of the penis, hypospadias of the urethra and lack of foreskin. About the same time that urethral closure is completed, the penis is fully extended, which happens to precede the formation of the foreskin. Studies have confirmed that disruption of the fiber growth factor (FGF)-10 gene may lead to hypospadias. Hoxa13 gene variants and loss of function will result in a combined loss of urethral plate epithelial Fgf8 and Bmp7 expression, leading to the development of hypospadias. Treatment of the disease Hypospadias must be surgically corrected. The purpose of surgery: first, to correct the hypospadias deformity, it is necessary to remove the ventral fibrin of the penis and completely straighten the penis. Secondly, to shape the urethra and to position the opening as close to normal as possible. Surgical indications: Except for the coronal hypospadias, which can be done without surgery, all other types must be corrected by neck surgery. Surgical methods: According to statistics, there are more than 150 surgical methods. It should be treated differently according to the surgeon’s branch, the patient’s age and penile development. Generally speaking, the treatment is completed at an early age, which can eliminate the psychological impact of the patient, but the younger the age, the less cooperative, coupled with the small penis, the operation is difficult, so the chance of surgical failure increases. Therefore, some people advocate staged surgery, i.e., removing the fibrous cord at an early age to correct the inferior flexion deformity, and then performing stage II urethroplasty after the penis has developed. Correction of deformity: Surgery is the only effective method. It should generally be done before entering school because the penis is already large and the child can actively cooperate with the surgery and avoid psychological damage after entering school. There are many different types of corrective surgery, depending on the specific case and medical conditions to choose different surgical methods, can be divided into about two categories. 1, staged surgery: the first stage of correction of penile hypospadias, foreskin from the dorsal side to the ventral side, to provide conditions for urethral reconstruction surgery. The current stage surgery is performed six months after the first stage surgery, using the ventral foreskin of the penis to build a new urethra so that the urethra opens at the head of the penis. Successful surgery will enable upright urination and fertility in adulthood. 2.One operation: This is the conventional surgical method used in hospitals. In a single operation, the downward curvature of the penis is corrected, the accumulation of foreskin on the dorsal side of the penis is eliminated, the urethra is built with the bladder mucosa instead, and the urethra is opened at the normal part of the head of the penis. This procedure is more in line with the normal physiological structure and has a similar appearance to that of a normal person. Patients can be spared the pain of multiple surgeries, with few complications, high success rate and more satisfactory results. Complication prevention and control Common complications include urinary fistula, stricture, wound infection and dehiscence, etc. Preventing the occurrence of complications is the trick to achieve success. Adequate preoperative preparation, delicate intraoperative operation and careful postoperative care can reduce the occurrence of complications. The most common complication would be fistula created after reconstruction of the urethra due to poor wound healing. This complication is associated with hematoma formation, wound infection, excessive length of the reconstructed urethra, use of insufficient skin with too much tension, or poor surgical technique and materials. To reduce the incidence of fistulae, patients with severe hypospadias should be operated on in multiple sessions, and hematoma and wound infection should be avoided as much as possible. The skin used should be as minimally invasive as possible and have an adequate blood supply, use non-reactive sutures and small instruments, reduce the retention of foreign bodies and tension in the suture, increase the contact area, improve surgical technique and apply proper urinary drainage. Post-operative wound dehiscence, urethral and urethral stricture, urethral diverticulum or difficulty in urination may also occur occasionally, but these are technical problems that can be avoided. Preoperative preparation The requirements for preoperative preparation for hypospadias are more stringent than those for general urethral surgery and have certain special features. In addition to the preparation before general urethral surgery, the following points should be made. 1, the penis is too small, the appropriate application of male hormone treatment, after the penis development, and then surgery. 2.For those who have urinary tract infection, the infection must be strictly controlled before surgery. 3.Wash the perineum with soap and water every day for 3 days before surgery, and use chlorhexidine wet compresses. 4.Check the position of the urethral opening in detail, correctly estimate the position of the urethral opening retraction after penile straightening, and also measure whether the skin of the foreskin, penis and scrotum can be utilized. Through a comprehensive judgment, it is decided whether to use a stage or staged surgery and what type of surgery. The anesthesia and position used for all types of surgery for suburethral cleft are basically the same. Ketamine anesthesia is appropriate for young children, and lumbar or epidural block anesthesia is available for children and adults. The penile type of hypospadias is operated in the horizontal position, and the scrotal and perineal types are operated in the bladder amputation position. Postoperative precautions I. To correct hypospadias, the first thing is to ensure the success of urethral reconstruction, of which the foreskin flap method is of course the best, other methods include penile flap method and skin graft method. The most common problems are urethral fistula and contracture leading to urethral stricture, etc. Second, correction of penile curvature deformity, the focus is to release the fibrous tissue and other lesions that cause the penile curvature of the tissue involved. But be careful not to damage and cut off the white membrane of the penis, otherwise it is easy to cause secondary penile curvature. Third, the preoperative, intraoperative and postoperative measures to prevent infection. From preoperative cleaning, all the aseptic operation and the application of antibiotics during surgery, postoperative urethra and local wound good care, the application of reasonable and effective antibiotics, which is important to remove the urinary catheter. Fourth, attention to the prevention and control of penile erection is also an important measure to ensure the success of the operation, and the short-term application of estrogen is necessary. Fifth, penile wound treatment, care to appropriate, intact pressure dressing is particularly important to prevent blood leakage, dead space, etc. Urethral fistula and stricture are usually shown at a later period, but of course, corresponding preventive and control measures should be taken, such as method selection, careful intraoperative operation, attention to urethral anastomosis, etc.