Definition:It is the protrusion of the contents of a cavity thru a defect in the wall of the cavity.
An Analogy : If there is a defect in the walls of a container , the contents of the container tend to come out of the container.
The human abdomen is also like a container with its walls made up of the abdominal muscles.If there is a defect in the muscle wall , the contents of the abdomen ( viz, small bowel , omentum, parts of large bowel ) tend to protrude thru the defect giving rise to a lump beneath the skin.This occurs more so if there is a rise of pressure inside the abdomen ( e.g.. while coughing, lifting heavy weights etc.) forcing the contents out.
The above figure is a pictorial representation of an abdominal wall hernia with the intestine protruding thru the defect.
Hernias can occur in different parts of the body including the abdomen.
The common types of hernias in the abdomen are inguinal (groin) , umbilical or paraumbilical (near the umbilicus ) , incisional (thru a defect in the scar from a previous surgery).
Clinical Features of a Hernia
There are two clinical features which are characteristic of a hernia : Expansile cough impulse : ie. Expansion in the size of a lump / swelling on coughing.
Reducibility : ie. the swelling reduces into the abdomen on being pushed back or on lying down.
Since a hernia occurs due to a physical defect,it cannot be cured by medicine but requires a surgical repair.
The most common type of repair in adults is a mesh repair ; either open or laparoscopic.
The hernial sac is approached, the contents and the sac are reduced thru the defect.The hernial defect is then covered using a mesh made up of an artificial material and this mesh is fixed in place using sutures or tackers.This results in a tension free repair as opposed to when sutures were
used to close the defects.
The above illustration shows the repair of a hernia with reduction of its contents and the application of a mesh.This repair can be done either by open or laparoscopic method.