Some babies born shortly after the umbilical cord is broken find that there will be small bags in the umbilicus, when the baby cries the bag will increase in size and become somewhat hard, when the baby is quiet or sleeping, the bag in the umbilicus disappears, when gently squeezing this bag in the belly button, it will make a gurgling sound. So, what is this bag that is sometimes big and sometimes small and makes a rumbling sound? This bag is medically called an umbilical hernia. Umbilical hernia is a developmental defect that is common in infants and young children, with no difference in incidence between the sexes. How does an umbilical hernia occur? The cause of umbilical hernia is related to the anatomical characteristics of the umbilicus. During fetal life, the umbilicus contains important blood supply vessels for the fetus, and after birth these tubes are then occluded and become fibrous cords that heal with the scarred skin after the umbilical cord is shed, so there are no developed muscles in this part and it is a weak zone. The umbilical hernia is formed when the umbilical cord bulges outward for various reasons that increase the abdominal pressure, such as crying, coughing, and diarrhea. What is inside the bag? In infants less than 1 year old, most umbilical hernias are within 1 to 2 cm in diameter, while older children can have a diameter of 3 to 4 cm. The protruding viscera are mostly the greater omentum or small intestine, and there is no adhesion between the wall and the contents of the sac. What are the manifestations of umbilical hernia? Umbilical hernia is a round or oval lump, which disappears when the baby is quiet and increases in size when the baby cries, toddles, coughs or moves. How to treat umbilical hernia? Umbilical hernia is usually painless and does not cause gastrointestinal dysfunction, but it should be noted that some babies may experience localized distension. Most umbilical hernias in infants and young children can heal on their own. As the baby grows older and the abdominal muscles develop, the hernia hole gradually narrows and closes, usually at the age of 1 to 2 years or even 3 to 4 years. For umbilical hernia of about 1 cm, no treatment is needed. For umbilical hernia of more than 2 cm, the baby under 2 years old can continue to be observed for 3 to 6 months, and if it does not close, surgery can be performed. It should be noted and pointed out that the elderly at home may propose to use coins to compress the protruding umbilicus and bandages to tighten the umbilicus, which cannot achieve the purpose of assisting self-healing because the umbilicus is still open when compressed, and cannot promote the reduction of the umbilicus. Mothers should not really worry too much because even surgical repair is a very simple procedure. The baby will recover quickly.