The bowel may be narrowed by the contraction of the scar left behind by a healed ulcer due to tuberculosis, typhoid fever or other cause. When such strictures are present, the peristaltic movements of the intestine are often so strong as to be visible in a thin patient through the abdominal walls. Such cases require operation.
Cancer of the colon is not infrequent, constituting about nine per cent of all cancers. Cancer occurs most frequently in the cecum or ascending colon, and next most frequently in the rectum or pelvic colon, points at which the greatest delay of the feces occurs.
Cancer of the colon is not infrequently secondary to cancer in some other location. When cancer exists or has existed in the breast, stomach, or elsewhere, obstinate constipation should lead to a careful physical examination including an X-ray examination of the colon with special reference to the presence of organic obstruction.
Acute obstruction due to "telescoping" of the intestine requires immediate surgical attention.
Chronic constipation is held to be sometimes due to such a telescoping of the pelvic colon into the rectum. This condition is probably quite rare, but it possibly may be more frequent than has been hitherto supposed. Such cases require surgical attention.
The feces are formed by the gradual absorption of the digested foodstuffs, and the drying out of the mass of debris left through the absorption of water. When thus formed, the feces are slowly moved along the colon toward the lowermost part of the colon proper, the pelvic colon, where they are deposited, the pelvic loop filling from below upward. The filling begins at the bottom of the loop, the junction of the colon with the rectum.
At this point a new mechanism is provided to deal with the feces. They have become so dried and hardened by the absorption of their liquid part that they are no longer suited for transportation by the feeble peristaltic waves which continually course from one end of the intestinal tract to the other. They must be dealt with by a more powerful mechanism. This may be termed the discharging mechanism or device, and it is certainly a most remarkable apparatus. We need not repeat here the description of the process of defecation, which has been given in detail elsewhere. Briefly summarized, it consists of three voluntary and four involuntary acts.
1. Voluntary acts in defecation: (a) Contraction of the diaphragm, (b) Contraction of the abdominal muscles, (c) Compression of the abdomen by the thighs.
2. Ivoluntary acts in defecation: (a) Contraction of the colon, (b) Relaxation of opening of the anus, (c) Reinforced contraction of the abdominal muscles, (d) Strong contraction of the levator ani muscles lying behind the rectum.
When each of these several distinct voluntary and involuntary acts is promptly and efficiently performed, defecation is complete, and at least the lower half of the colon is completely emptied. Failure at any point results in incomplete defecation, and fecal matters are left behind, producing cumulative constipation. Let us note the different ways in which these several acts may be interfered with.
If the diaphragm is weak from disuse or general feebleness, if its movements are obstructed by corsets or waist bands, if it is tied fast by adhesions from pleurisy or crippled by hernia, it cannot act efficiently, and the amount of feces pushed down into the rectum may not be sufficient to call forth a vigorous act of defecation. The result will be that the colon will be only partially emptied, and cumulative constipation will result, though the rectum may be fully emptied and no sense of discomfort be felt. The pelvic colon will be gradually stretched by the accumulating contents until it becomes enormously enlarged and forms a reservoir of putrefying feces, by which the body is continually poisoned, and a great variety of diseased conditions produced. This condition is very common as the natural result of sedentary habits and corset-wearing.
When the abdominal muscles are weak, relaxed, separated, or otherwise inefficient, the results are the same as when the diaphragm fails to do its duty, for the two sets of muscles must work in cooperation.
The ordinary water-closet seat renders complete efficiency of the abdominal muscles and diaphragm practically impossible, since it does not permit of pressure by the thighs, an essential voluntary act in defecation.
A feeble, dilated, inflamed, thickened, elongated, adherent, overloaded, obstructed colon, cannot possibly contract with sufficient vigor to empty itself of its unclean contents. Yet such is the chronic condition of the colon in a very large proportion of cases as the result of the operation of some one or more of the causes which have been enumerated in the foregoing paragraphs.
Nervousness, apprehension or fear may prevent the normal reflex from acting. Hysteria or melancholia may paralyze a patient's colon as well as an arm or a leg.