Diagrammatic section of an intussusception: A, reflected tube; B, receiving tube or sheath; C, entering tube.
Causes.
—The causes of intussusception are obscure, postmortem findings or even the revelations of a laparotomy demonstrating conditions, but not often affording explanations. The presence of tumors, especially lipomas, which may even be pedunculated along the small intestine, has been demonstrated in a number of instances, and they have been supposed to be active factors in the first disturbance. Everything points to the association of disordered intestinal movements with the mechanical condition of obstruction, and the former are more frequently seen in the intestinal complaints of the young, along with the presence of masses of undigested food or impacted feces within the bowel, or the occurrence of intestinal polypi. The most complicated case of ileocecal invagination which ever came under my notice was associated with the presence of a polyp in the ileum. All of these conditions, save the presence of tumors, pertain more frequently to the young than to the aged. The influence of the ileocecal valve is also undeniable, and that at this region parts are more predisposed to invagination than elsewhere is quite obvious. In at least half of the cases that have been recorded no satisfactory cause could be shown. Any condition which causes severe intestinal colic may give rise to intussusception; the next most common causes are paralysis or weakening of some part of the bowel, such as may follow injury or disease, or the presence of tumors, while even the role which they play is not entirely explained ([Fig. 561]).
That invagination will produce mechanical obstruction is obvious, while the fact that such obstruction is not always nor necessarily complete incites surprise. The orifice of the intussusceptum is distorted, while the included portion may be greatly bent or curved upon itself, in addition to which the obstruction to the circulation leads to congestion, exudation, and swelling, and predisposes to active inflammation, all of which tend to still further narrow the passage-way. If, in addition to this, some tumor or hardened fecal mass be included in the grasp of the bowel involved it may be seen how complete shutting off of the intestinal tube may occur within a few hours. Invagination having occurred tends quickly to become irreducible; most commonly by the formation of adhesions, as lymph quickly exudes and bowel surfaces are by it thus glued together. Such adhesions may persist throughout the whole involved length of bowel or may occur at various scattered spots. As pressure becomes greater circulation of the invaginated portion is impeded and finally shut off, gangrene of the intussusceptum thus resulting. Cases occasionally terminate favorably through this actual condition, the included portion being finally cast off as a slough and passing onward and outward. It is on record, for instance, that six feet of invaginated bowel have thus been obtruded from the rectum after having sloughed, the patient eventually recovering. While this possibility, then, is present it is never safe to wait for it, and it is to be regarded simply as a happy accident when it occurs. Unless, then, a case of intussusception be very early and promptly operated, the included portion of the bowel may be regarded as dangerous and unsafe, unless upon disengagement it prove to have been but very slightly affected. Even then there is danger of immediate recurrence of the previous condition because of distention of the bowel above, paralysis of the part disengaged, and stretching of the part below. In proportion as obstruction becomes more complete distention of the bowel above the lesion, from accumulation and gas formation, will cause more and more distress, until finally complete paralysis of the muscular coat and possibly eventual rupture may terminate the case.
Fig. 561
Invagination of ileum, cecum, and ascending colon into transverse colon. One probe is passed into the appendix, the other into the invaginated portion of the ileum. (Rafinesque.)
In addition to the conditions above described, all of which are acute, there is known also a chronic form of intussusception, whose whole course is much slower and less severe, where symptoms of obstruction never become more than partial, but may involve any portion of the bowel, and with about the same relative frequency as the acute forms. Such a condition in the rectum, for instance, has been mistaken for cancer.
Symptoms.
—The special symptoms by which intussusception may be recognized, or at least by which suspicion is aroused, are, in addition to those common to all forms of acute obstruction, the abrupt onset, which may even occur during sleep, the late rather than the early occurrence of vomiting, complaint of tenesmus, the wave-like or colicky character of the pain, and the fact that along with the violent peristalsis of which this colicky pain is an indication diarrhea is a common accompaniment, the actual local coprostasis being masked by this fact. As the lumen of the bowel becomes occluded and fecal matter fails to pass, the evacuations become more bloody and contain little but mucus. Finally, almost pure blood may be passed. In no other form of obstruction is the passage of blood so distinctive as in this. Urine elimination is but slightly influenced, and strangury is an exceedingly rare feature. Meteorism is also less pronounced. The discovery of a tumor formed by the invagination will lend further aid in diagnosis. It may be felt either through the abdominal wall or by the rectum, and may be noted in about half of the cases. It is most frequently found in the ileocecal and colic varieties, and felt in the rectum with the lower colic forms. In children it is more distinct than in adults. The tumor may even take the outline of the involved bowel, is usually movable, but may be fixed. When such a tumor is felt within the rectum it may have to be distinguished from some intrinsic neoplasm of the lower bowel; but the history of the case should prove satisfying if the physical examination leaves one in doubt.