The location of the seat of the obstruction is not merely of theoretical value, but of great practical importance, for this decides the question as to where abdominal incision should be made in cases of operation. It will be useful to discuss first at what point of the abdomen the obstruction is situated, and secondly, what particular portion of the bowel it involves.

1. The point at which the patient first experiences pain is significant in case he is able to locate it definitely. In many instances, however, the pain is not experienced in one circumscribed spot, and is often located diffusely in the neighborhood of the navel. The presence of a tensely tympanitic intestinal coil, which does not change its configuration and thus makes the abdominal wall protrude asymmetrically, is of great importance; for, according to Von Wahl, such a coil is often found above the occluded segment of intestine. Strong peristaltic contractions running in the same direction over a certain region of the abdomen, especially if they return periodically and always in the same area, will serve to locate the place at which the obstruction is situated. For these peristaltic waves pass along the intestine down to the seat of the obstruction, which they are unable to overcome.

Palpation of the abdomen occasionally reveals the presence of a sausage-like tumor. This occurs especially in cases of intussusception. If such a tumor is present, the location of the obstruction is certainly easy. A thorough examination of all hernial openings will occasionally reveal an incarceration of the intestine and also show the site of the lesion. If there is no hernia the examination must be continued through the vagina and through the rectum . The exploration through the vagina will show whether the pelvic organs are normal, and if not, whether a tumor originating from the genital organs is compressing the intestines. Digital examination of the rectum will enable us to discover a stricture, an intussusception, or a tumor of the lower portion of the bowel. In some cases a thorough examination of the entire rectum and the descending colon may be undertaken with the whole hand under chloroform narcosis, according to the method of Simon. In cases of intussusception involving the sigmoid flexure and rectum, the anus often remains open (paralysis of the sphincters) and there appears an involuntary evacuation of a muco-bloody fluid from time to time.

2. Determination of the Portion of the Intestinal Tract in which the Obstruction is Situated. Small Intestine. If the obstruction is situated in the small intestine all the symptoms (pains, vomiting, collapse) are, as a rule, much more intense and appear sooner than in obstruction of the large bowel. Soon after the commencement of the disease, there is copious vomiting which may become fecal after a short period. The meteorisin at the beginning is localized in the upper part of the abdomen, while the lower part remains unchanged. Pronounced visible peristaltic waves in the small intestine also point to an occlusion situated within the latter.

Jaffe 1 was the first to show that obstruction of the small intestine gives rise to pronounced indicanuria. As early as the second or third day of the obstruction, indican can be found in the urine in large quantities. In obstruction of the large bowel there is as a rule no indicanuria, and if it appears it does so only later in the disease, on the sixth or seventh day. The higher up in the intestinal tract the obstruction is situated, the sooner and the more frequently anuria may appear. Injections of water into the bowel may secure a fecal evacuation. The colon can also be filled with a large amount of water or gas.

If the obstruction is situated within the duodenum or in the upper part of the jejunum, it can often be easily recognized. Obstruction of the duodenum above Vater's papilla will manifest the same symptoms as acute dilatation of the stomach in consequence of a stricture. There will be ischo-chymia and continuous vomiting of chyme. An obstruction situated within the duodenum below Vater's papilla will give rise to vomiting of large quantities of pure bile. The vomited matter may contain acids from admixture of gastric juice. It is never fecal in character. The gastric region is protuberant but sinks in after a spell of vomiting.

If the obstruction is situated within the beginning of the jejunum the vomiting assumes at first a greenish hue (decomposed bile) which may be followed by the vomiting of pure unchanged yellow bile. Occasionally the vomited matter assumes a fecal character. Obstructions situated within the duodenum or at the beginning of the jejunum, as a rule, are unaccompanied with indicanuria.

1 Jaffe: Centralbl. f. die med. Wissenschaften, 1872.

Obstruction of the Large Bowel. The symptoms here are usually less violent and appear a little later than in the obstruction of the small intestine. Fecal vomiting often appears long after the establishment of the occlusion, and it may even be absent if the obstacle is situated at the beginning of the descending colon or lower down. The meteorism is in most instances limited to the lower parts of the abdomen and also to the lumbar regions. In occlusion of the descending colon it may be noticeable that at first there is a protrusion in the left iliac region, afterward a protrusion of the transverse colon, and ultimately the ascending colon will also become tympanitic. As mentioned above, indicanuria will be absent during the first five or six days of illness.

With regard to the determination of the occlusion within the lower parts of the colon, Brinton's 1 method, already in use over fifty years ago, is very valuable. It consists in filling up the bowel with water through the rectum. If not more than half a quart can be injected, the obstruction must be situated in the upper part of the rectum. If one to two quarts can be injected, the obstruction must be situated above the sigmoid flexure, in the descending colon, or still higher. In case obstruction is situated in the ascending colon four quarts or still more can be injected and retained in the bowel. Insufflation of air or carbonic acid gas into the rectum will also occasionally show the seat of the obstruction, if the latter is situated in the descending or the transverse colon, as there will be a filling up with gas of the free portion of the bowel up to the obstructed point. When the obstruction is located beyond the transverse colon, however, it will not permit of distinct recognition by this method.

1 Brinton; "On Intestinal Obstruction, London, 1867.