A hernia that protrudes from the umbilical ring is called an umbilical hernia, and a hernia that protrudes from the white line fissure on the midline immediately above or below the umbilical ring is called a paraumbilical hernia and is usually classified as an umbilical hernia. Umbilical hernia is clinically divided into two types: infantile umbilical hernia and adult umbilical hernia, with the former being far more common than the latter. The incidence may be related to race and is common in African populations. The incidence in white populations ranges from 1.9-18.5%. Umbilical hernia is more common in infants and children up to 1 year of age, and is more common in girls than boys, with a higher incidence in premature and low birth weight infants. In adults, umbilical hernia is more common in women over 40 years of age, especially in obese people, with a male to female ratio of about 1:3. I. Etiology and pathology The umbilicus is located in the lower part of the midline of the abdomen, equivalent to the height between the 3rd and 4th lumbar vertebrae. It is the trace left in the center of the anterior abdominal wall during the development of the embryonic body wall. In the 12th week of embryonic life, the abdominal wall converges in the center to form the umbilical ring, which is the channel for the yolk duct connecting the prointestine and the yolk sac, as well as the channel for the umbilical artery, vein and umbilical ureter, and is the latest point of peritoneal fusion. After the fetus is delivered, the umbilical cord is ligated, the umbilical artery and vein are thrombosed, and the umbilical ring formed by the abdominal white line is self-locking, forming a dense umbilical fascia locally. The skin of the umbilicus is thin and there is no fatty tissue under the skin. The skin, fascia and peritoneum are directly connected, which is a natural weak area of the abdominal wall and is one of the most frequent sites of extra-abdominal hernia due to abdominal pressure. Umbilical hernias in infants and children occur days or weeks after the umbilical cord stump is detached. It is a congenital condition formed when the abdominal wall fascia is not fused at the vascular penetration of the umbilical cord, the umbilical scar is not completely closed or is too weak, and the anterior and posterior sheaths of the rectus abdominis muscles on both sides are not united at the umbilicus during infancy and there is a defect. When the infant cries or coughs, the abdomen expands and the white line is overstretched, which widens the unclosed umbilical ring even more and the abdominal contents protrude outward through the umbilical ring. The etiology of adult umbilical hernia is not completely clear, except for a very small number of persistent or recurrent infantile umbilical hernia, which is usually an acquired disease, with a prevalence of 6% of all adult abdominal wall hernias. The clinical manifestation is a round or semicircular swelling at the umbilicus, which disappears when lying quietly, but increases in size and tension when doing actions to increase intra-abdominal pressure (such as crying, coughing, standing, etc.), and the contents of the hernia can be reduced or disappeared by pressing the swelling lightly with the hand, and the unclosed umbilical ring can often be felt. The mass is usually located on the upper right side of the umbilical ring, where the umbilical vessels used to pass and where the tissue is weak. The neck of the hernia sac is usually not large, but because the umbilicus consists of only a few thin scar tissues, impaction or strangulation rarely occurs. Sometimes, the tissue covering the umbilical hernia in infants and children can collapse due to trauma or infection. The diameter of the hernia ring is mostly about 1 cm, and 2-3 cm is rare. Most of them have no obvious clinical symptoms, but some may have local swelling discomfort. In adults, the umbilical hernia is mainly a paramedian hernia, so the hernia mass is often located above or below the umbilicus, often hemispherical, soft, and with a sensation of impact when coughing, and a huge umbilical hernia may dangle downward. The mass is retracted and a round hernia ring can be palpated at the umbilicus. Unlike umbilical hernia in infants and children, most patients experience discomfort such as hidden pain in the upper abdomen due to the involvement, and sometimes nausea and vomiting. Since the tissue around the hernia ring is tough and the edges are sharp, and the hernia contents tend to adhere to the hernia sac, it is prone to entrapment or strangulation. In pregnant women or those with cirrhotic ascites with umbilical hernia, traumatic or spontaneous puncture may sometimes occur. Under normal circumstances, the umbilical ring of infants can continue to narrow spontaneously after birth, and usually the umbilical hernia can be completely closed within 2 years and can heal spontaneously. If the diameter of the umbilical ring is still greater than 1.5-2 cm after the age of 2 years, and if the defect increases progressively during the observation period, and if incrustation or rupture occurs, surgical treatment should be considered. Usually, if the umbilical hernia does not heal spontaneously at the age of 4 years or older, surgical treatment is an option. Conservative treatment can be done by taping or blocking the umbilical ring with a hard object (coin). In the former case, the umbilicus is held against the gauze pad to make the umbilicus sink in, and then wide strips of tape are pulled together on both sides of the abdominal wall toward the midline of the abdomen and fixed to prevent the protrusion of the hernia mass, so that the skin at the midline of the abdominal wall becomes a longitudinal groove and the umbilical hole can gradually heal and close. In the latter case, the umbilical hernia can be retracted into the abdominal cavity by holding the end of the finger against the umbilicus, filling the umbilical fossa with sterile cotton balls, wrapping a round coin or clothespin larger than the umbilical ring with gauze, compressing the hernia ring, and fixing it with transparent dressing or adhesive tape, which should be changed every 1-2 weeks. The use of adhesive tape may sometimes irritate the skin and cause blisters, so tincture of benzoin can be applied to the skin before application to increase the viscosity of the tape and reduce skin irritation. In addition, an umbilical hernia belt or lap band may also be an option. Removal of the belly button in young children may have adverse psychological effects, so umbilical hernia surgery in infants and children is performed by preserving the umbilicus. The surgery is performed under general anesthesia. A curved incision is made 1-2 cm below the umbilical hernia, the subcutaneous tissue is separated, the anterior rectus abdominis sheath, hernia ring and hernia sac are exposed, the abdominal white line is incised medially, the hernia sac is freed, the hernia contents are retracted, the hernia sac is removed from under the umbilical skin, the peritoneum is sutured, the sheath margin of the rectus abdominis muscle on both sides is interrupted with nonabsorbable sutures, and the skin is sutured layer by layer. (B) Adult umbilical hernia Adult umbilical hernia cannot heal on its own and requires surgical treatment. The traditional surgical method is simple suturing or Mayo method surgery, but the recurrence rate can reach 10-15%. In recent years, scholars at home and abroad have adopted various hernia repair materials for tension-free repair of umbilical hernia, and there are various surgical approaches, but the results are satisfactory. The commonly used surgical methods are introduced here. Mayo method repair A transverse shuttle incision is made at the center of the umbilicus, and if the mass is less than 2 cm, an arc-shaped incision around the umbilicus can also be made below the umbilicus. The skin and subcutaneous tissue are incised in turn to reveal the hernia sac and umbilical ring. The hernia sac is incised and the hernia contents are retracted to the basal transverse end. The rectus abdominis sheath, rectus abdominis muscle and peritoneum are separated, and after excision of the external hernia cover, the peritoneum and posterior rectus abdominis sheath on both sides are sutured together as one interrupted layer, and then the anterior rectus abdominis sheath is sutured together. 2, repair of muscle anterior artificial material (Onlay repair method) The hernia sac can be found in front of the rectus abdominis tendon membrane, the hernia sac can be removed or the hernia sac can be completely freed, the hernia ring can be sutured closed, and then the subcutaneous and part of the anterior rectus abdominis sheath can be freed, the patch can be placed above the anterior rectus abdominis sheath with the edge of the patch exceeding the edge of the umbilical ring by 3-5 cm, fully spreading, and the edge of the patch can be fixed to the anterior sheath with interrupted sutures of non-absorbable sutures. To prevent postoperative subcutaneous fluid accumulation, closed drainage was placed in front of the patch. 3. The posterior fascial anterior or preperitoneal patch repair method (Sublay repair method) separates the hernia sac, introverts and retracts the hernia sac, then, a circumferential freeing is made in all directions between the peritoneum and the posterior sheath of the rectus abdominis muscle, that is, the preperitoneal gap, and the patch is placed within this gap, exceeding the edge of the defect by 3-5 cm in the upward and downward directions, and the circumference of the patch is fixed with sutures to the posterior sheath of the rectus abdominis muscle, and the incised anterior sheath on both sides is fixed with the patch several stitches. 4. Tension-free repair with double-layer repair device The hernia sac is separated as described in the previous method. After internalization of the hernia sac, the anterior peritoneal space is freed along the hernia ring to the left and right, and the UHS patch is placed into the umbilical ring. The bottom layer of the patch is placed into the anterior peritoneal space and fully spread, with the edge of the superhernia ring being greater than 3 cm. The middle column of the patch is sutured and fixed to the umbilical ring, and the upper layer of the patch is also free from the gap in the anterior rectus abdominis sheath to be patched and laid flat on the surface of the anterior rectus abdominis sheath. 5.Laparoscopic umbilical hernia repair method (IPOM repair method) Three trocar, one observation hole and two operation holes are placed on the side away from the umbilical hernia. The hernia contents are returned and the hernia ring defect can be closed with abdominal wall puncture sutures, then an anti-adhesion patch is placed with the umbilical hernia defect as the center and the surrounding area should exceed the defect by 5 cm, and the patch is suspended with abdominal wall puncture sutures and then fixed twice with a staple gun. Compared with open tension-free repair, laparoscopic surgery has the advantages of minimally invasive, minimal umbilical injury, and preservation of the belly button.