HERNIA THROUGH THE MESENTERY, OMENTUM OR OTHER FOLD OF PERITONEUM.
Definition. Causes: Concussions in horse especially, anatomical conditions in cattle, pediculated tumors, dystokia, hernia of small intestine in horse, ox, broad ligament, pelvic hernia. Lesions: Congestion, hemorrhage of hernial viscus, adhesions, softening, thickening, strangulation. Symptoms: Intestinal obstruction, rectal exploration. Treatment: Laparotomy.
Definition. This consists in a protrusion through an opening, congenital or acquired, in the double fold of peritoneum (mesentery) which passes off from the abdominal wall to support a viscus, or that which passes from organ to organ (omentum).
Causes. The lacerations of mesentery or omentum are attributed to sudden concussions of various kinds (falls, blows, leaps, violent efforts), and have been especially found in horses in which the bulk and weight of the contents of the digestive organs furnish a special predisposition. In ruminants in which the contents of the abdomen are equally bulky and heavy the lesion is rarely seen, probably because the great bulk of the ingesta lies in the first three stomachs, and because the large intestines are folded up in the mesentery which supports the small, thereby strengthening this means of support and restricting the freedom of movement on the part of the intestines themselves. In carnivora the limited bulk of the intestines and their contents, and the relative shortness of the mesenteric folds largely obviate the predisposition.
Pediculated tumors of mesentery or omentum may drag on the delicate membrane so as to cause laceration, and circumscribed peritonitis, by producing softening and friability, may act as a causative factor. Violent straining in defecation or parturition is another cause of laceration.
In solipeds the loosely suspended and eminently mobile small intestine is the viscus which most commonly forms a hernia through such adventitious openings, either through the great mesentery, the great omentum, the gastro-splenic omentum, the mesentery of the umbilical vein (falciform ligament of the liver), or the gastro-hepatic omentum. Cases are on record, however, in which the floating colon, the double colon and even the cæcum formed herniæ through the peritoneal lacerations.
In cattle the most common lesion is the hernia of a knuckle of intestine through a laceration in the mesentery, but, the rupture has also occurred in the great omentum and exceptionally in the broad ligament of the uterus which is very extensive in these animals. Pelvic hernia or gut tie as usually described is dependent on a laceration of the mesentery of the spermatic artery.
Lesions. The fold of intestine which makes the hernia is liable to become strangled, and sometimes twisted in the opening, so that the circulation of blood and ingesta is interrupted, congestions and hemorrhages set in, and necrosis and general infection follow. Oftentimes a fibrinous exudate is thrown out, binding together the intestinal convolutions, and attaching them to the margins of the mesenteric or omental opening. Similarly the lips of the lacerated wound in the mesentery become covered with blood clots, or congested, or infiltrated, and sometimes the seat of extensive extravasations. The inflamed membrane may soften, become friable and tear more extensively, or if the patient survives, the exudation becomes organized, thickening and strengthening the margins of the wound and causing them to contract so as to strangle the enclosed loop of intestine.
Symptoms. The indications are those of intestinal obstruction, to which accordingly the reader is referred. The only possible indication of the exact nature of the lesion is to be obtained by rectal exploration. Herniæ through the meso-colon or broad uterine ligament may be reached in this way, and possibly diagnosed.
Treatment. Laparotomy alone gives any hope of success, and this will only be warranted when a certain diagnosis has been reached.