What is a hernia?

A hernia is defined as an abnormal protrusion of an object through the wall of a cavity, the wall of which has weakened to the point that it no longer can contain the object inside the cavity. In simple speak, "something pokes out from within".

In the case of abdominal hernias, the "cavity" is the abdominal cavity, the "wall" is the muscular wall of the abdomen or pelvis (the pelvic floor) and the "something" poking out is usually a bit of intestine, a piece of fatty tissue or the stomach. Just about any structure that lies freely in the abdomen or pelvis can herniate out of the cavity. Hernias are sometimes colloquially referred to as "ruptures" or "breaches".

What causes a hernia?

Hernias may be broadly classified into CONGENITAL or ACQUIRED varieties. Congenital hernias are present from the moment of birth and are the result of incomplete development of the foetal abdomen. The classic example of this is an umbilical hernia (see below) which produces a small residual bulge in the bellybutton, or umbilicus, when the severed umbilical cord shrivels up. Another example is that of an inguinal hernia present in the groin of some infants in which the testicle, having descended into the scrotum, has left the "door" (the abdominal wall) open as it passed through. Acquired hernias are, as their names imply, acquired during a person's lifetime after birth. Such hernias arise as a consequence of any circumstances that place the abdominal contents under strain or any circumstances that weaken the abdominal wall. These hernias rarely occur suddenly (called an acute hernia), but usually as a gradual consequence of aging, physical exertion or chronic illness over many years.

Common types of hernia

1. Hiatus hernia

Due to a weakness in the diaphragm (the muscles separating the abdomen from the chest cavity), the stomach may partially rise up into the chest cavity behind the heart. This often drags the junction of the oesophagus (gullet) and stomach upwards too, such that the valve controlling acid and food passage doesn't work efficiently. Acid may reflux upwards into the oesophagus to cause inflammation and pain ("heartburn") or a bitter taste in the mouth ("water brash"). These symptoms are particularly bad after a meal when the stomach is engorged, or when the person lies flat. Food may also become trapped in the portion of stomach stuck in the chest, leading to indigestion, or a sensation of pain behind the breast bone, or a tendency to belch and regurgitate.

2. Inguinal hernia

Such hernias occur in the groin area ,either left or right, in a region situated between the top of your hips and the bony pubic area. The weakness is due to a partial lack of muscle (no meaty muscle here) and partially because the abdominal wall must make way here for the foetal gonads to develop  in the embryonic stage. It is an area of "natural" relative weakness. Patients typically note some discomfort in the area during or after physical activity or when coughing/sneezing. A soft "squidgy" lump is often seen or felt just beneath the skin, especially when standing upright. The lump often seems to disappear when lying down. Over time, the lump usually expands until eventually, in men, it may extend right down into the scrotum causing it too to distend. Pain may radiate down into the scrotum or cause some numbness or tingling in the overlying skin.

3. Femoral hernia

These hernias occur in the groin area too, in a region situated at the very top of the thigh in the groove between abdomen and limb, close to the pubic area. The weakness lies in the lowest portion of the abdominal wall where the latter must make way for some major blood vessels to travel down into the lower limb. Patients experience symptoms and lumps just as they do for inguinal hernias. Occasionally, pain may radiate into the inner thigh.

4. Umbilical hernia or Paraumbilical hernia

Umbilical hernias are "true" or "direct" hernias as the bulge is directly through the umbilicus. Paraumbilical hernias emerge around, or close to, the umbilicus. These hernias manifest usually with a painless lump that is noted incidentally. Over time the lump may enlarge and become symptomatic, typically causing pain with coughing, sneezing, bending forwards or physical exertion. Up to 10% of infants are born with congenital umbilical hernias, with 80% of these disappearing during infancy such that only 2% of people have one by the time they reach adulthood.

5. Ventral or epigastric hernia

Such hernias occur anywhere along the midline of the abdomen, running from the tip of the breast bone down to the pubic bone, but the vast majority are situated in the upper half of that line above the umbilicus. They may be singular or multiple, and are thought to be due to residual weakness arising when the two halves of the embryonic abdomen fuse together incompletely in some areas. As the abdominal wall is sinewy and tough along this midline, such hernias are often very small yet sometimes quite tender as they try to squeeze through the gap in the sinew. Patients usually present with a small swelling, localised tenderness or pain with exertion or bending forwards.

6. Incisional hernia

Such hernias arise through a scar from a previous incision. Patients who have undergone previous abdominal surgery have wounds in their abdominal wall which are sewn up at the end of the operation. These wound edges may sometimes fail to unite in the healing process, leading to gaps in the scar, or the wound edges may unite but simply be of insufficient strength over time to resist continual rises of pressure inside the abdomen during straining. Even small wounds like keyhole wounds can do this, but it is typically larger wounds that were formed from major surgery at times of poor health that are affected thus. Patients may witness a bulge in the area of the wound, or experience pain, or feel a soft lump. They may often report feeling "unsupported" in the area as if they might "unzip" their abdomen.

7. "Sportsman's" hernia a.k.a "Gilmore Groin"

This is not, using the strict definition of the word, a hernia. It is an injury to structures in the groin which produces symptoms similar to that of a groin hernia. It is also not exclusive to sportsmen, so the name is rather unfortunate. Typically, an injury occurs during a particularly vigorous act, like a sliding tackle in football, a lunge for a low drop-shot in tennis or a wrench during a skiing accident. It may also occur as a relatively minor injury that becomes exacerbated through repetitive activity, since the sportsman or active person seldom treats the problem properly or rests for long enough. Three classical injuries are seen: a tear in the aponeurosis (a flat sinewy sheet forming the outermost layer of abdominal "muscles"), a tearing off of the rectus muscle's tendon from the pubic bone, or a tearing of the adductor muscle's tendon from the pubic bone. The first is the commonest; all three injuries require a genuine "repair", as opposed to a simple suture repair or mesh patch, as we do for other proper hernias.  

Many other varities of abdominal or pelvic hernias can arise, but these are all pretty rare compared to groin hernias, umbilical hernias and hiatus hernias.

More about groin hernias


 Types of groin hernia

Two types of hernias occur in the groin area: inguinal hernias and femoral hernias (see above). Inguinal hernias are further classified into "direct" and "indirect" types, based on whether the hernia emerges directly through the floor of the inguinal (groin) canal, or whether it emerges indirectly along the tunnel through the tunnel's entrance. Much is made of this by the generation of doctors who had to choose between various techniques of repair, but nowadays it is largely an irrelevance since both inguinal hernia varieties are treated with a mesh "patch" repair. Doctors may also occasionally refer to hernias with eponymous names, like Richter's hernia or Littre's hernia, which refer to what has entered into the hernia. They may also use the word "sliding", but these are of little relevance to your surgery. Terms that are more important are the following:

     incarcerated     - the hernia is stuck and won't go back in

     strangulated     - the hernia has become so tight that its contents have been denied blood

     recurrent            - the hernia has been repaired previously

     congenital         - the hernia was probably present from birth


Anatomy of the groin

The abdominal wall is usually comprised of three layers. In the lower abdomen there is not much fleshy muscle, but instead a layer of flimsy tissue called the "transversalis fascia" and a layer of sinewy tendon (a bit like the silverside of beef) called the "aponeurosis". The transversalis fascia forms the floor of a space whilst the aponeurosis forms a roof. The floor is separated from the roof as the developing embryonic testicle forces its way between them. This process occurs in females too, but in females the testicle never develops. The space created by this process is called the inguinal canal. In males it contains the blood vessels of the testicle, the sperm tube called the vas deferens, and a nerve; these are collectively called the Spermatic Cord. In females the canal contains only the nerve and a rudimentary remnant of gonad development called the Gubernaculum.

At the lower edge of the abdominal wall lies a ligament called the Inguinal Ligament, spanning from the hip girdle to the pubic bone on each side. Major blood vessels and nerves leave the abdomen beneath the ligament and head to the thigh; they are referred to as the femoral artery, vein and nerve. They are surrounded by a protective spongy tissue called the fascia and they too have to emerge through the fascia during foetal development, creating a femoral canal.

The inguinal canal and femoral canal are both areas of relative weakness, into which the hernia can protrude from the abdomen.


Natural history i.e. how they behave over time if not treated

Because hernias arise through an area of inherent anatomical weakness, they do not "go away" without a surgeon rectifying that weakness. In other words, once you have a hernia it is there to stay unless you have surgery. When the abdominal contents are put under pressure, e.g. when lifting, coughing, straining, exercising etc. the pressure is distributed througout the abdominal wall. The weakest area will "give" the most, so inevitably the hernia receives the most pressure. Some patients are lucky and the hernia does not progressively enlarge very much over their remaining lifetime and gives them no symptoms. The majority, though, experience a progressive enlargement of the hernia.

Femoral hernias seldom become very large, partly due to the lack of available space to expand into, but mostly because they beome pretty troublesome even when small and end up being repaired. Inguinal hernias have no such restriction and can become enormous. In males they can extend into the scrotal sac, termed an "inguinoscrotal" hernia. In both genders the genitals can become obscured by the huge bulge.

As hernias enlarge, they inevitably produce more and more symptoms. The achy discomfort at the end of an active day may become a discomfort throughout an active day, then become a discomfort throughout an inactive day and then finally become a pain even at rest. The enjoyment of one's personal or professional life becomes increasingly compromised as such symptoms progress. Partial, temporary relief can sometimes come from compression hosiery or from a truss (a device strapped tightly around the waist to apply external pressure to the hernia), but these are a cumbersome ineffective solution for many patients (Click "Learn about your surgery" in the left hand menu on this page).

Obstruction occurs when intestinal content is unable to pass through intestines that are caught in the hernia. This produces a blockage of the gut with consequent distension of the abdomen, colicky pain and vomiting. Emergency surgery to release the intestine and repair the hernia is required.

Strangulation of a hernia is a rare but serious complication arising in a hernia. If the hernia is extremely tight, the pressure within it may be so great as to prevent blood from entering the hernia's contents. Without blood, the contents will die and eventually rot. This is a surgical emergency that requires not just repair of the hernia but removal of the dead organs in the hernia, as gangrene will set in and death could follow.