In acute cases the attack is sudden, the symptoms violent, and, unless the cause is speedily removed, life ends in a few hours or at most in a few days. In chronic cases the causes act comparatively more slowly, the symptoms are chronic and less urgent, and danger of death less imminent. In this class the cause is not uncommonly spontaneously relieved, and the individual restored to perfect health without the aid of medicine or the surgeon's art. This result may happen in apparently the most desperate cases.
This classification of acute and chronic obstruction is necessary for a proper clinical study of the subject, but it should be remembered that in practice there will be found some cases which partake of many of the symptoms of both acute and chronic obstruction, making it difficult to determine to which division the cases properly belong. It will also be seen that some, at first, well-marked acute cases subside and become chronic in character, and that (old) chronic cases of obstruction sometimes suddenly change their nature and become acute. Again, some of the causes mentioned as giving rise to acute obstruction of the bowel in rare instances produce symptoms of chronic obstruction, and some of the causes referred to as giving rise to symptoms of chronic obstruction in rare instances provoke signs of acute obstruction. These cases are exceptional. As a rule, the following list embraces conditions which produce symptoms of acute obstruction:
1. Congenital malformations.
2. Impaction of foreign bodies, gall-stones, enteroliths, etc.
3. Twisting of the bowel—volvulus.
4. Internal strangulation by loops, bands, false membranes, diverticula, mesenteric pouches, slipping of a portion of bowel into natural or unnatural openings, diaphragmatic hernia, etc.
As a rule, the following causes produce symptoms of chronic intestinal obstruction:
1. Constipation and fecal accumulation.
2. Stricture of the bowel, sometimes cancerous.