These hernias come through a weakness in the join between the right and left rectus abdominis muscles (these muscles are described as the “six pack” which are readily seen in athletic individuals). The right and left rectus abdominis muscles fuse together at the linea alba (literally a white line). In epigastric hernias a tiny piece of fat squeezes through a tiny hole in the linea alba. These hernias can be exquisitely tender but the hole is too small for a piece of bowel to come through and therefore are not dangerous.
This is less common than the inguinal hernia but occurs more commonly in women than men. It is usually smaller than an inguinal hernia appearing just below where you would expect an inguinal hernia to be. On occasions, it can be difficult to tell between an inguinal and femoral hernia. It is unusual for a femoral hernia to come and go in the same way an inguinal hernia does: it is always present. Because the hole through which the hernia has to pass is so very tight, there is a significant chance that any bowel that passes into it will become trapped (incarcerated) and its blood supply cut off (strangulated). (see “is a hernia dangerous?” under frequently asked questions).
Whenever a cut is made into the abdominal cavity the resulting wound, even when fully healed, may not to be as strong as the original abdominal wall. If the muscle gives way then an incisional hernia develops. They may involve a variable length of the wound. The most dangerous ones are big enough to allow a knuckle of bowel to enter, but tight enough to strangle its blood supply (see “is a hernia dangerous?” under frequently asked questions).
This is the commonest type of hernia and the one we tend to think of when someone says they have a rupture or hernia. It occurs predominantly in men and may be confined to one side or be present on both (bilateral). Patients with hernias on both sides may have them appear together or there may be a gap of many years before the second one becomes apparent. Not uncommonly patients develop an inguinal hernia after heavy lifting during which they may experience a sharp pain in the groin and notice the appearance of a swelling.
Paraumbilical and Umbilical hernias
Umbilical hernias are congenital ie they are present from the time of birth. Most significant umbilical hernias are repaired in childhood. Whilst it is not uncommon for them to be noticed on abdominal examination, most are small, cause no problems and do not require repair.
Paraumbilical hernias appear above the “belly button” and like epigastric hernias come through the linea alba. They are usually larger than epigastric or umbilical hernias and require repair because of the risk of bowel contained within them becoming strangulated.
This is a rare type of hernia that appears on the edge of one of the rectus abdominis muscles (these muscles are described as the “six pack” which are readily seen in athletic individuals) 4 or 5 cm below the “belly button”.