出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/06/12 16:59:29」(JST)
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| Hypospadias | |
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Different types of hypospadias
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| Classification and external resources | |
| Specialty | Urology, medical genetics |
| ICD-10 | Q54 |
| ICD-9-CM | 752.61 |
| DiseasesDB | 29907 |
| MedlinePlus | 001286 |
| eMedicine | ped/1136 |
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[edit on Wikidata]
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Hypospadias /haɪpoʊˈspeɪdɪəs/[1][2] is a birth defect of the urethra in the male where the urinary opening is not at the usual location on the head of the penis. It is the second most common birth abnormality in boys, affecting approximately 1 of every 250.[3] In approximately 90% of cases, the opening (meatus) is on or near the head of the penis (glans), referred to as distal hypospadias, while the remainder have proximal hypospadias with a meatus near or within the scrotum. Shiny tissue seen extending from the meatus to the tip of the glans, which would have made the urinary channel, is referred to as the urethral plate.
In most cases the foreskin is also underdeveloped and does not wrap completely around the penis, leaving the underside of the glans penis uncovered. There may also be downward bending of the penis, commonly referred to as chordee.[4] This is found in 10% of distal hypospadias[5] and 50% of proximal hypospadias[6] at the time of surgery. The scrotum may be higher than usual to either side of the penis, called penoscrotal transposition, adding to the abnormal overall appearance.
Hypospadias is thought to result from failure of the urinary channel to completely tubularize to the end of the penis. The cause of hypospadias is not known. Most often, it is the only abnormal finding, although in about 10% of cases hypospadias may be part of a syndrome with multiple abnormalities.[7][8]
The most common associated defect is an undescended testicle, which has been reported in approximately 3% of infants with distal hypospadias and 10% of those having proximal hypospadias.[9] The combination of hypospadias and an undescended testicle sometimes indicates a disorder of sexual differentiation, and so additional testing may be recommended.[10][11]
Otherwise no blood tests or X-rays are routinely needed in newborns with hypospadias.[3]
Hypospadias is thought to result from failure of the urinary channel to completely tubularize to the end of the penis. The cause of hypospadias is not known. Most often, it is the only abnormal finding, although in about 10% of cases hypospadias may be part of a syndrome with multiple abnormalities.[7][8]
The most common associated defect is an undescended testicle, which has been reported in approximately 3% of infants with distal hypospadias and 10% of those having proximal hypospadias.[9] The combination of hypospadias and an undescended testicle sometimes indicates a disorder of sexual differentiation, and so additional testing may be recommended.[10][11]
Otherwise no blood tests or X-rays are routinely needed in newborns with hypospadias.[3]
Hypospadias is usually diagnosed in the newborn nursery by the characteristic appearance of the penis. The urinary opening (“meatus”) is lower than normal, and most boys have only partial development of the foreskin, lacking the normal covering for the glans on the underside. The abnormal “hooded” foreskin calls attention to the condition. However, not all newborns with partial foreskin development have hypospadias, as some have a normal urinary opening with a hooded foreskin, which is called “chordee without hypospadias”.
Megameatus with intact prepuce (MIP) variant of hypospadias occurs when the foreskin is normal and there is a concealed hypospadias. The condition is discovered during newborn circumcision or later in childhood when the foreskin begins to retract. A newborn with normal-appearing foreskin and a straight penis who is discovered to have hypospadias after a circumcision was started can have circumcision completed without worry for jeopardizing future hypospadias repair.[12][13] Hypospadias is almost never discovered after a circumcision.
The treatment usually recommended for hypospadias is surgery, with the goal to restore normal appearance and function to the penis. A urinary opening that is not surrounded by glans tissue is more likely to “spray” the urine, which can cause a man to sit to urinate because he cannot reliably stand and hit the toilet. Downward curvature of the penis can impair sexual activity as an adult. In addition, the partially developed foreskin looks neither circumcised nor natural.
Surgery extends the urinary channel to the end of the penis, straightens bending, and corrects the foreskin abnormality by either circumcision or by repairing it to look normal (“prepucioplasty”), depending on the desire of care-givers.
When the hypospadias is third degree, or there are associated birth defects such as chordee or cryptorchidism, the best management can be a more complicated decision. A karyotype and endocrine evaluation should be performed to detect intersex conditions or hormone deficiencies. If the penis is small, testosterone or human chorionic gonadotropin (hCG) injections may be given to enlarge it before surgery.[3]
Surgical repair of severe hypospadias may require multiple procedures and mucosal grafting. Preputial skin is often used for grafting and circumcision should be avoided before repair. In a minority of patients with severe hypospadias surgery produces unsatisfactory results, such as scarring, curvature, or formation of urethral fistulas, diverticula, or strictures. A fistula is an unwanted opening through the skin along the course of the urethra, and can result in urinary leakage or an abnormal stream. A diverticulum is an "outpocketing" of the lining of the urethra which interferes with urinary flow and may result in post-urination leakage. A stricture is a narrowing of the urethra severe enough to obstruct flow. Reduced complication rates even for third degree repair (e.g., fistula rates below 5%) have been reported in recent years from centers with the most experience, and surgical repair is now performed for the vast majority of infants with hypospadias.[citation needed]
Hypospadias repair can be done in full-term, healthy infants at any time from 3 months of age. Premature babies generally have surgery done at 6 months or older. Using these guidelines, most babies can undergo repair as same day surgery, without need to stay in the hospital afterwards.
The results of surgery are probably not influenced by the age at which repair is done,[14][15] but older boys are more likely to recall the event. Teens and adults typically spend one night in the hospital after surgery.
Hormones potentially increase the size of the penis, and have been used in boys with proximal hypospadias who have a smaller penis. Numerous articles report testosterone injections or topical creams increase the length and circumference of the penis. However, few studies discuss the impact of this treatment on the success of corrective surgery, with conflicting results.[15][16] Therefore, the role, if any, for preoperative hormone stimulation is not clear at this time.
Hypospadias repair is done under general anesthesia, most often supplemented by a nerve block to the penis or a caudal block in order to reduce the general anesthesia needed, and to minimize discomfort after surgery.
There are many techniques which have been used during the past 100 years to extend the urinary channel to the correct location. Today the most common operation, known as the tubularized incised plate or “TIP” repair, rolls the urethral plate from the low meatus to the end of the glans. This procedure can be used for all distal hypospadias repairs, with complications afterwards expected in less than 10% of cases.[17][18]
There is less consensus regarding proximal hypospadias repair.[19] TIP repair can be used when the penis is straight or has mild downward curvature, with success in 85%.[20] Alternatively, the urinary channel can be reconstructed using the foreskin, with reported success in from 55% to 75%.[21][22]
Most distal and many proximal hypospadias are corrected in a single operation. However, those with the most severe condition having a urinary opening in the scrotum and downward bending of the penis are often corrected in a 2-stage operation. During the first operation the curvature is straightened. At the second, the urinary channel is completed.
Example of penis with hypospadias
Penis with hypospadias (1) and two fistulae (2)
Most boys having hypospadias repair heal without complications. This is especially true for distal hypospadias operations, which are successful in over 90% of cases.
Problems that can arise include a small hole in the urinary channel below the meatus, called a fistula. The head of the penis, which is open at birth in boys with hypospadias and is closed around the urinary channel at surgery, sometimes reopens, known as glans dehiscence. The new urinary opening can scar, resulting in meatal stenosis, or internal scarring can create a stricture, either of which cause partial blockage to urinating. If the new urinary channel balloons when urinating a child is diagnosed with a diverticulum.
Most complications are discovered within six months after surgery, although they occasionally are not found for many years. In general, when there are no apparent problems after repair in childhood, new complications arising after puberty are uncommon. However, some problems that were not adequately repaired in childhood may become more pronounced when the penis grows at puberty, such as residual penile curvature or urine spraying due to glans dehiscence.
These complications are usually successfully corrected with another operation, most often delayed for at least six months after the last surgery to allow the tissues to heal sufficiently before attempting another repair. Using modern surgical techniques, a normal appearing penis can usually be expected from hypospadias repair. Results when circumcision or foreskin reconstruction are done are the same, and so care-givers can choose whichever option they wish.[23][24] (Figure 4a, 4b)
While most hypospadias repairs are done in boys, occasionally an adult was not operated and then desires surgery because of urinary spraying or unhappiness with the appearance. Other adults wanting surgery have complications that were never fully corrected during childhood.
There has been a general opinion that operations done in adults are less successful than those in boys. For that reason some adults have been discouraged from having corrective surgery. However, a direct comparison of surgical results in boys versus men found they had the same outcomes, and therefore men can undergo hypospadias repair or reoperations with good expectations for success.[15]
Hypospadias is among the most common birth defects in the world and is said to be the second most common birth defect in boys, occurring 1 in every 250 births.[25]
Due to variations in the reporting requirements of different national databases, data from such registries can not be used to accurately determine either incidence of hypospadias or geographical variations in its occurrences.[3]
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| リンク元 | 「尿道下裂」 |
| 拡張検索 | 「penoscrotal hypospadias」 |