The contents are usually made up either of intestine or omentum, or both. If the hernia is reducible, the bowel and omentum present a normal appearance; but if irreducible and the hernia of long duration, numerous pathological changes are likely to occur. The omentum be comes thickened and adherent to the sac, usually at the neck, or to the bowel, if that be present. A small amount of serous exudate is not infrequently pres ent in an irreducible hernia. If the her nia contains omentum alone, it is called an epiplocele; if bowel alone, an enlerocele; if both are present, entero-epiplocele.
Etiology.—About 25 per cent. of per sons with a rupture give a family history of hernia; while 40 per cent. are rupt ured before the age of 35, 60 per cent. after that age.
Family history of hernia has not often been brought forward. Case in which patient's both parents had been affected, —the father with the right scrotal ,her common to his father, brother; and son; the mother also had a femoral her nia. It would seem most probable that the lad inherited his defect—overpatent inguinal rings—from his father, but the laxity of tissue present in his mother's case and shared by his sister, as shown by their possession of femoral hernias, may have counted for something in the size of the protruded mass. J. Kynaston Couch (Lancet, Oct. 26, '95).
The occupation is an important factor in causing hernia; those trades requiring the most severe muscular effort having the highest proportion of persons rupt ured. The increased liability to mus cular strain in men is undoubtedly an important factor in explaining the greater proportion of ruptures in male than in female subjects. Parturition is a frequent cause in the female, especially of umbilical hernia.
There were 7433 cases of hernia met with in the male and 2534 in the female during a period of three years' consulta tion at the Central Bureau of Assistance in Paris, among patients applying for bandages. Inguinal hernia constituted 911 per cent. of these cases, 6220 of the men suffering from this form, double in 4126 cases, and single in the rest, occupy ing the right side in preference to the left in proportion of 1.46 to 1. Of all the cases a congenital origin could be definitely ascertained in only 479 cases. Berger (La Sem. 1116d., Oct. 26, '95).
The frequency is independent of race, but appears to be in relation to easy circumstances or the reverse. Among members of the literary profession her nia is rare. Between ages 5 and 15 the condition is uncommon. After 40 years of age the proportion rapidly increases. Bertillon (Le Bull. WA., Dec. 4, '95).
Inguinal hernia is much more common in the male, and the reason for this is undoubtedly the fact that in man the inguinal canal is so much larger than it is in woman on account of the passage of the spermatic cord through this canal.
On the other hand, femoral hernia is much more common in women because of the relaxation of the abdominal wall in all directions, due to child-bearing, and also because of the difference in anatomical structure. The female pelvis is much flatter and more horizontal than that of the male; consequently Poupart's ligament is relatively longer and tends to make the femoral canal wider and consequently weaker. Garrigues (Med. News, Jan. 22, '9S).
Anything that tends to weaken the abdominal walls may be the indirect cause of hernia; for example, traumatism followed by the formation of cicatricial tissue, contusions, obesity, ascites.
The chief exciting cause of hernia is a sudden strain; the larger proportion of hernias, especially in adult life, come on soon after some unusual effort. The hernia generally begins with a slight fullness over the canal, often associated with a little soreness or feeling of dis comfort. In rare cases a fully-developed hernia may immediately follow sudden strain.
Two cases in which strangulation occurred simultaneously with the first appearance of the hernia are quoted by Bull and Coley (Dennis's "System of Surgery," vol. iv).
Indirect causes of hernia are chronic bronchitis, pulmonary affections in gen eral, and habitual constipation.
Fourteen eases of hydrocele in which, during operation for that affection, a small hernial sac, the remains of a non obliterated peritoneo-vaginal canal, was discovered at a point corresponding to the internal abdominal ring, though there was nothing in the history or symptoms to suggest hernia. To this number 11 more cases operated upon for hydrocele added, in S of which the same condition was found. The three excep tions noted have caused the writer to modify his former statement that hydro cele is always associated with non obliteration of the peritonco-vaginal process and consequent hernia, though he still emphasizes the frequent associa tion of the two conditions. In his opinion this subject is of sufficient importance to merit the careful study of all sur geons, as, in the event of frequent coin cidence of hydrocele with previous peri toneo-vaginal process being proven by repeated observations, it might be ad visable, in operating for hydrocele, to extend the incision to the inguinal canal in order that the existence of such a previous process might be discovered and obliterated, thus insuring the patient against a possible interstitial external oblique hernia. V. Remedi (Gaz. ()sped., March S. 1903).