HERNIA (Latin, a rupture, a burst, a descent), 'a swelling formed by the displace ment of a soft part, which protrudes by a natural or accidental opening from the cavity in which it is contained. The three great cavities of the body are subject to these displacements. The brain, the heart, the lungs and most of the ab dominal viscera may become totally or partially displaced, and thus give rise to the formation of hernial swellings. Displacements of the brain and of the organs of the chest are, however, extremely rare, and are in general the result or symptom of some accident or disease. They are frequent in war times from gun-shot wounds and from the necessary surgical procedures. Many parts of the abdominal wall may become the seat of hernias, but they most commonly ap pear in the front lower regions, which, being destitute in great measure of muscular fibres, and being the site of many of the openings lead ing from the abdomen to the limbs, offer less resistance to the displacement of the viscera. Hernias are most common in the groin, at the navel, more rarely in the vagina, at the interior and upper part of the thigh, and at its lower and posterior part. They have received different names from their positions. All the abdominal viscera, with the exception of the duodenum, the pancreas and the kidneys may form a hernia, but they are not all displaced with the same facility. The omentum and in testinal canal escape easily; the stomach, liver and spleen rarely form hernias. Most of the viscera, when displaced, push the peritoneum forward before them ; this membrane thus forms a covering to the hernia, which is called the hernial sac. If the hernia, with its sac, can be entirely replaced, it is said to be reducible; if, from its size or other cause, it cannot be re stored to its former place, it is irreducible.
Among the predisposing causes of hernia may be ranked any circumstance which dimin ishes the resistance of the abdominal walls, whether natural or accidental; such as muscular weakening of those walls by a forced distension, as in pregnancy, by accidents, by lifting heavy weights or by excessive standing. Any pro longation of the viscera which tends to bring them in contact with points at which they may protrude, and articles of dress which push the organs toward the weaker parts of the abdom inal wall (as corsets), may also produce hernia.
The efficient causes of hernia are all circum stances which may break the equilibrium exist ing between the abdominal walls and the vis cera, which react and mutually press upon each other. The simultaneous contraction of the abdominal muscles and of the diaphragm, which takes place on every violent effort,. is one of the chief of these cases. Hence sneezing, coughing, leaping, playing on wind-instruments, etc., may be the direct cause of hernia.
The symptoms of a hernia are the existence of a tumor or swelling at any point of the abdo men, but more particularly in the region of the groin. A reducible hernia is not a very trouble some disease, but may become so by acquiring an increase of size, and by strangulation. A hernia is said to be strangulated when it is not only irreducible, but also subjected to a con tinual constriction; this constriction may be pro duced by different causes, but it is generally a constriction at the opening through which the hernia protrudes. As soon as a patient per ceives that he is affected with a hernia he should have recourse to medical advice, for the disease is then in its most favorable state for treatment. The hernia is immediately reduced, and must then be subjected to a constant compression. This is done by means of a truss (q.v.). An irreducible hernia must be supported with great care. All violent exercises and excess in diet must be avoided. Strangulated hernia, present ing greater danger, requires moreprompt relief. The object of treatment is to relieve the con striction. If the reduction cannot be effected by other means, an operation will be necessary. This consists in dividing the parts which pro duce the constriction. The longer this it tion is delayed, the more dangerous t will become. After the parts are healed, the open ing must be subject to compression, as in the case of a simple hernia. Radical operation for hernia is the most advisable form of treatment. It is safe in the hands of a competent surgeon.