The root of the mesentery is placed obliquely across the spinal column, arising from the left side above and crossing obliquely to the right side below. Monks has shown how easily we may make practical application of this fact in determining approximately to what part of the bowel tube a given loop may belong, since it is necessary only to follow it down to the mesenteric insertion, and from this estimate what proportion of the entire distance is represented.
INJURIES OF THE MESENTERY.
Obviously the mesentery may be injured in the same way as any other of the abdominal viscera, either by contusions, lacerations, punctures, or otherwise. Here the immediate danger is from hemorrhage, while a more remote but quite possible danger is that of thrombosis of some of the vessels and its consequences in the direction of necrosis.
Erdmann has recently reported two cases of complete detachment, for several inches, of the mesentery at the intestinal border, as well as a case of multiple lacerations in the peritoneal coat of the mesentery with hematoma. While the latter might not be so serious, the former will almost invariably determine gangrene of bowel from lack of blood supply; all of which shows the difficulty of diagnosis, and furnishes a further argument for intervention when, after an abdominal contusion, the patient has abdominal rigidity or pain, with or without evidences of hemorrhage, either from the stomach, rectum, or bladder. These features are sufficient without the addition of those by which a more certain or minute diagnosis can be made.
THROMBOSIS AND EMBOLISM IN THE MESENTERIC VESSELS.
Mesenteric occlusion was first described by Virchow in 1859. Whether it involves first the arterial or the venous circulation seems to matter but little. Of course in one case it is to be regarded as embolic, in the other as thrombotic. In this location either condition is harder to explain than in many other places. The mesenteric veins have no valves and collateral circulation is poor. Mitral stenosis and arterial sclerosis will often account for the former. For thrombosis search has to be made for some local infectious process, either in the veins of the pelvis, the kidney, or the intestines. It seems to occur least often when it might be most expected, i. e., after typhoid.
The blood supply may be simply shut off from portions supplied by one of the mesenteric vascular branches, or, should the main branches be involved, from the entire intestinal tract. I have myself reported two cases of practically complete rapid gangrene of the entire alimentary canal, due to lesion of this kind, explanation being forthcoming in neither case.
Symptoms and Signs.
—The more complete the occlusion and the more extensive the area deprived of blood the more sudden and overwhelming will be the onset. This is always sudden and characterized by intense and often paroxysmal pain, so agonizing, in fact, as scarcely to be quieted even by morphine. While this is common, instances have been known in which the disease has run an almost painless course. Diarrhea is frequently an early symptom, evacuations being profuse and bloody. Symptoms of obstruction are not uncommon, perhaps followed later by loose stools. Vomiting occurs usually early and becomes fatal in a few hours. The general physical signs are intensely acute, with rapid pulse, subnormal temperature, and meteorism, beginning early and becoming more pronounced. Abdominal rigidity also constitutes a distressing feature, which, while indicating the gravity of the condition, masks its diagnostic features. If the patient live long enough fluid will accumulate in the peritoneal cavity. The cases terminate with complete collapse and delirium. When the inferior mesenteric vessels are involved tenesmus is a more prominent characteristic than when the lesion is confined to the upper, as the colon and rectum are supplied from the former.
The surgeon may have to distinguish between the condition just described and the following: Perforating ulcer of the stomach or duodenum (which will have a previous history), possibly so-called phlegmonous gastritis; acute obstruction of the bowel (whose onset is rarely so acute); pancreatitis, which would, at least at first, produce almost identical symptoms; acute splenic infarct (when the early symptoms would probably be referred to the region of the spleen); acute appendicitis; acute cholecystitis, and that acute peritonitis to which either of these might lead; a ruptured ectopic pregnancy; and possibly certain intrathoracic lesions, especially pneumonia in the lower lobes. Mesenteric occlusion is essentially a fatal condition, at least when extensive. There have been known cases where so limited an extent of the bowel and mesentery were involved that an exsection, made early, has proved successful, but when anything like the entire alimentary canal or its major portion becomes necrotic there is no hope for the patient.[65]