An umbilical hernia is the protrusion of abdominal contents through a weakness in the abdominal wall, at the umbilicus.
What causes this?
During the development of the foetus, abdominal organs are formed outside the gut, and later return to inside the abdominal cavity through an opening, the umbilical ring. This same opening houses the umbilical blood vessels from the placenta, which feed the foetus. After birth, this opening slowly closes by itself, with closure being complete in nearly all children by 5 years. This often takes longer in black children.
Incomplete closure of this opening allows abdominal contents to protrude when the pressure in the abdomen is increased, such as during crying, coughing, sneezing or straining at stool.
Conditions in babies predisposing to umbilical hernia are:
- Ehlers-Danlos syndrome (hypermobility and hyperelasticity of the skin)
- Down syndrome
- mucopolysaccharidoses (glycogen storage diseases)
- ascites (abnormal fluid collection in the abdominal cavity)
Umbilical hernia in adults is an acquired condition, three times more common in females than in males, and associated with conditions of raised intra-abdominal pressure, such as
Natural history and symptoms
Paediatric umbilical hernias nearly always heal on their own, by the time the child reaches the age of five. Hernias with an opening of more than 1,5cms, or with an underlying predisposing condition are less likely to close spontaneously. Umbilical hernias seldom become complicated by contents which cannot be returned to the abdominal cavity, or which become strangulated due to swelling blocking off their blood supply.
Umbilical hernias in adults are more likely to contain omentum or omental fat, which may become stuck in the hernia, causing pain and tenderness. If a small knuckle of bowel becomes trapped or strangulated, immediate intervention is needed. These patients may have classic signs of bowel obstruction.
Paediatric umbilical hernias are not always obvious, so much depends on the mother’s account. If the child cries during the examination, the hernia may be demonstrated. A fingertip in the umbilicus will detect the edges of the ring. Hernial contents are usually easily returned to the abdominal cavity.
In adults, the hernia may be more evident, as the contents more often tend to become ‘stuck’ in place. There is often pain and tenderness over the hernia. Signs of bowel obstruction warrant urgent surgery, to prevent bowel gangrene.
Most paediatric umbilical hernias require no treatment, other than regular monitoring. However, large hernias which fail to close will need surgery. In adults, any umbilical hernias which cause symptoms warrant surgery. Surgery may be done under local or general anaesthesia, and some centres do it laparscopically. Regardless of the approach, the operation aims to close the defect, sometimes with the aid of a mesh graft if the defect is very large.
Those hernias which heal by themselves do so without complications. Surgical repair of umbilical hernia is highly successful.