What is a hernia?

In its broadest sense, a hernia is simply a defect of the innermost layer of fascia, or tough connective tissue layer, of the abdominal wall. This definition encompasses all types of abdominal wall hernias including inguinal and femoral groin hernias, abdominal wall, post-operative incisional hernias, diaphragmatic, as well as others. The presence of a hernia can allow intra-abdominal contents such as intestines to pass through this defect into the subcutaneous tissue. When this happens the intestines can become incarcerated or strangulated (see below for further details). The following discussion will be limited to hernias of the groin of which there are two main types; inguinal and femoral, the more common of which is the inguinal hernia.

A femoral hernia is a hernia that penetrates the femoral ring. This is the path that the femoral vessels take to exit the pelvis and enter the leg.

An inguinal hernia is a hernia occurring in the inguinal canal; a natural defect in the abdominal wall fascia which allows passage of the spermatic cord in the male and analogous non functional structures in the female. The entrance of the inguinal canal from within the abdomen is called the internal ring, and the exit of the canal is into the scrotum (or labia majora), called the external ring. Hernias which follow the path of the spermatic cord through the internal ring into the inguinal canal are called indirect inguinal hernias and are congenital in origin. Hernias which directly penetrate the innermost layer of the abdominal wall and enter the inguinal canal are called direct inguinal hernias and usually occur later in life. This type of hernia is more commonly related to years of straining or heavy exertion.

Who gets hernias?

Both inguinal and femoral hernias occur in all age groups; however, inguinal hernias are far more common. Males and females are affected almost equally; however, femoral hernias occur more commonly in females. Many inguinal hernias encountered in young people are congenital, meaning they are born with them. Frequently they become apparent during infancy and are repaired at that time. Nevertheless, many of these congenital hernias do not become apparent until young adulthood. In some cases, they do not become evident even until much later in life.

In contrast, direct inguinal hernias more commonly occur in older men with a history of strenuous activity or heavy lifting. It often takes years to develop. At surgery, the abdominal fascia involved with the hernia is attenuated and weak. Of course, this type of hernia can be seen in younger people and in women as well. Many times, an inguinal hernia is found to have both direct and indirect components where there is a hernia sac or intestines penetrating the internal ring and entering the inguinal canal, in addition to a weakness in the fascia of the floor of the canal with ballooning of the fascia and a large direct inguinal hernia.

What are the symptoms of hernias?

The most common presenting symptom of a hernia is a bulge in the groin or, in the case of a femoral hernia, the upper thigh. Frequently there is some pain at the sight of the defect but not usually much. The bulge may go away when lying down or with direct pressure applied against it. If the bulge does not go away with any form of manipulation the hernia may be incarcerated.

Incarceration of a hernia means that intra-abdominal contents can be present and trapped in the hernia sac, such as intestine or fat, or less commonly other organs such as bladder or ovary. If the hernia sac cannot be reduced back into their normal intra-abdominal position this can cause obstruction of the intestine with the symptoms of abdominal distention, vomiting, and inability to have a bowel movement. Incarceration of the hernia contents may lead to strangulation of the hernia contents.

Strangulation occurs most typically when intestine protrudes through a relatively small hernia defect and either twists upon itself or becomes swollen which can compromise its own blood supply. If not corrected urgently this may result in loss of blood supply and gangrene of that intestinal segment or organ. Symptoms at this stage include all of those previously mentioned plus severe abdominal pain, fever, confusion, change in mental status, and shock.

This progression from a simple reducible hernia to an incarcerated hernia with strangulation can happen unpredictably and suddenly. It can occasionally happened that a patient with an uncomplicated hernia can be scheduled for elective surgery only to have the patient present within the next few days in the emergency room with incarceration. It is for this reason that a surgeon will recommend to their patient who have hernias that they should be repaired as soon as is conveniently possible.

What is the treatment?

There are several described inguinal hernia repairs, the majority of which involve the direct sewing of tissue layers with non-absorbable stitches and the use of mesh. The repair of the hernia defect with a prosthetic mesh or "screen" serves to replace or bolster that part of the abdominal wall where the defect has occurred. These repairs have good recovery and acceptable recurrence rates (<5%). However, the disadvantage of all tissue repairs is that they create some degree of tension on the tissues and recovery tends to be painful. In patients with bilateral hernias, it is often recommended that both should not be repaired at the same time in adults. In small children the technique of repair is somewhat different and bilateral repairs are less painful and therefore, more common.