A dorsal penis length of 2 cm or less in the neonatal period is considered to be short penis. In contrast, the definition of small penis in adult men lacks a uniform standard. This is mainly due to differences in ethnicity, region, living habits, the state the penis is in at the time of measurement, and the method of measurement. The average length of adult male penis in China is 8.08cm, and the average effective length of erection is 12.4cm, with 9.5-15.5cm accounting for 95%. Most men are mature at the age of 18; the length and girth of the penis are almost equal when in state and erect. Penis length is measured by pressing a hard ruler next to the penis toward the pubic bone and measuring the length of the penis when it is flaccid, and then tugging on the penis when it is fully erect. A penis shorter than 4cm when flaccid, 7cm when stretched, and 9.5cm when effectively erect is considered a small penis. However, an erection with an effective length shorter than 9.5cm can still be functionally normal and can be used for sexual intercourse, and the hardness of the penis during erection is more important than the length. What is the mechanism of occurrence of micropenis? Basically, it is caused by testicular insufficiency during embryonic period. Representative disorders include Prader-Willi syndrome and Kallman syndrome with hypogonadotropic gonadal insufficiency. endocrine therapy is advocated for micropenis found before the age of 18, and in patients who fail to respond to endocrine therapy, treatment decisions should be made after the child has matured. The hypothalamic-pituitary-testicular axis is not stabilized before the age of 1 year with testosterone propionate 25 mg intramuscularly once a month for 3 months. If this period is passed the hormone can be supplemented intermittently when LHRH begins to be secreted in nocturnal pulses around the age of 7 years. If it is caused by the absence of androgen receptors in the penis itself and insensitivity to androgens, androgen therapy is ineffective. In those who are often accompanied by urethral malformation and have extremely short penis, a change in the sex of rearing should be considered, and female episiotomy should be performed during the neonatal period or infancy. In such patients with extremely short penis, attempts to retain the male gender and surgical lengthening of the penis are unlikely to bring the penis to normal size and function to normal. Intermittent hormonal therapy is listed below, 2-3 sessions over 1 year (usually in spring and summer) What is the concept of penile lengthening? Penis lengthening refers to the use of surgical methods to cut off part of the ligament, so that part of the penile corpus cavernosum, which was originally fixed on the pubic bone, is released from the body and protrudes outside the body, thus increasing the length of the penis. As a result, the tree grows by 1 foot. The result is that the tree grows by 1 foot. After the roots are pulled up, the tree still has 2 feet of roots left to absorb nutrients and water, and does not die. Penis lengthening is a surgical procedure to make the penis reach a relative lengthening purpose by a similar reasoning, not an absolute lengthening of the penis. General penis lengthening surgery can lengthen the penis by an average of 3 cm, but it varies from person to person, some up to 5 cm, some may be less than 3 cm. The key to surgery is to cut and release the penile suspensory ligament, too little release will not achieve the purpose of lengthening, too much cutting may destroy the stability of the penis, and may hurt the deep blood vessels, affecting the erectile function of the penis. What is the surgical incision design and procedure for penile lengthening? The incision is designed at the pubic symphysis as appropriate. The inverted “V” incision is mostly preferred (63%), followed by the “M”, “Z” and “V” shapes. The length of the two branches of the “V” shape is 4 cm, and the distance between the two branches is 5 cm at the root of the penis (lateral). the skin is cut according to the incision design line, the superficial suspensory ligament of the penis is exposed, the superficial fascia and loose connective tissue on both sides of the ligament are separated, and the superficial suspensory ligament is cut. The superficial suspensory ligament is 1.2-2.0 cm wide and 1.0-1.8 cm thick. 1.4-1.8 cm from the deep surface of the superficial suspensory ligament is the deep suspensory ligament of the penis, which is in the shape of a triangle with the bottom facing downward, starting from the lower part of the front of the pubic symphysis, which is free and completely cut off. The dense connective tissue below is about 1.5 cm, and the separation is considered adequate when the free edge of the subpubic notch and the pubic bone branch can be palpated. The deep dorsal penile vein should be carefully separated to avoid injury when exposed during dissection (if necessary, sutures can be cut and tied). The connective tissues on both sides of the pubic arch are pulled together and sutured centrally and lined at the lowest part of the pubic arch, and the skin on both sides of the penile root is sutured and fixed to the fat pad at the pubic arch to prevent re-adhesion of the severed ligaments; the skin incision at the penile end is fixed to the deep fascia of the penis with intradermal sutures to prevent the skin from slipping toward the tip of the penis. A rubber strip is placed inside the wound to drain the tissue fluid and blood from the surgical wound. What are the indications for penile lengthening? 1, penile dysplasia: the length of the penis is less than 10 cm when erect and cannot meet the sexual requirements of the female partner; 2, congenital small penis: the erect length and circumference is 5-8 cm, penis lengthening and thickening surgery can be performed at the same time; 3, penile cancer after partial penectomy; 4, other, such as: the penis is slightly small or basically normal after erection, but the patient has psychological barriers, and even affects normal sexual life. Is penile lengthening surgery safe? Penis lengthening is a mature and affirmative operation with fast recovery after surgery, and the stitches can be removed in 7-10 days, which has little impact on life and work. Mild edema of the penis after surgery is the most common complication, anti-inflammatory drugs are available for 3-5 days, and the edema usually subsides a week after surgery. Occasionally, a small amount of blood may accumulate in the incision, but this can be avoided by complete intraoperative hemostasis or placement of appropriate drainage. However, it is not a very simple surgery, and if not handled well, it may be ineffective in light cases or damage important anatomical structures such as the corpus cavernosum, dorsal penile artery, deep penile vein, and dorsal penile nerve, resulting in postoperative hematoma, infection, and even erectile dysfunction. Does it have any effect on erection after surgery? The most significant cost of this surgery is the reduced stability of the penis after surgery. Sometimes the penis does not reach the angle of less than or equal to 90 degrees that the normal penis naturally makes with the abdominal wall when erect before surgery. There is no effect on erectile function per se.