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. Adult umbilical hernia is more common in women over 40 years old, especially in obese people, and the ratio of men to women is about 1:3.
I. Etiology and pathology
The umbilicus is located below the midline of the abdomen and is 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.
Clinical manifestations
The clinical manifestation is that a round or semi-circular mass can be seen in the umbilicus, which disappears when lying quietly, but increases in size and tension when doing actions to increase intra-abdominal pressure (e.g. crying, coughing, standing, etc.), and light pressure on the mass can shrink or disappear the contents of the hernia, 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, it is rare to have ingrowth or strangulation. 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 who have umbilical hernia, traumatic or spontaneous puncture may sometimes occur.
III. Treatment
(I) Umbilical hernia in infants and children
Under normal circumstances, the umbilical ring of infants can continue to narrow spontaneously after birth, and the umbilical hernia usually closes completely within 2 years and can heal spontaneously. Therefore, for umbilical hernia in infants and young children, active non-surgical treatment should be taken at an early stage if there are no special circumstances, and surgical treatment should be considered after the age of 2 years if the diameter of the umbilical ring is still greater than 1.5-2 cm and the defect increases progressively during the observation period, and if impaction or rupture occurs. 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). Alternatively, treatment with an umbilical hernia belt or lap band may be an option.
Removal of the belly button in young children may have a negative psychological impact on them, so umbilical hernia surgery in infants and children is performed by preserving the umbilicus.
(ii) Adult umbilical hernia
Adult umbilical hernia is not self-healing and requires surgical treatment.
The traditional surgical method is simple suture 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 main two repair methods are open to and laparoscopic. Compared with open tension-free repair, laparoscopic surgery has the advantages of minimally invasive, small damage to the umbilicus, and can preserve the belly button.