Embryology and Histology teach us that the rectum is a development of the hypo blast and fibroblast, in connection with the rest of the colon. Further, we learn that the rectal mucous membrane is formed from the hypo blast; the sub mucous layer and muscles from the inner layer of the fibroblast, and that the rectum proper ends with the free border of the semi-lunar valves or serrated margin of the pectin.

Also we learn from embryology that the rectum and anus are the development of two distinct layers of the blastoff; that the blood supply is different and independent, comes from different sources and returns by different routes to the general circulation. Should there be an arresting in the development of one, there is not necessarily an arresting in the other. In other words, a malformation in the anus does not mean a malformation of the rectum. Malformations of either one of these organs, however, are likely to be associated with deformities of the same photogenic origin. Children with malformations of the rectum are very apt to have a cleft-palate or other deformities of the intestinal canal. Malformations of the anus may be associated with deformities of the euro-genital organs, the bladder or the vagina. It will be seen then that malformations of the rectum and anus may be accompanied by deformities in any of the pelvic organs, or of the bony structure, dependent upon the embryo logic formations.

The enumeration of these malformations, as given to us in 1781 by Appendectomy, seems to have stood the test of time for convenience of classification, and, but for the theory of embryo logic formation, would suffice for all purposes to this day. Therefore a rearrangement to conform with this theory,as given by Cuttle, dividing them into those of neoplastic, mes-elastic, and hypothetical origin will be accepted here.

Anus

1. Partial occlusion.

2. Abnormal narrowing.

3. Anal opening at some abnormal point, such as the perineum, scrotum or sacrum.

4. Complete occlusion.

5. Entire absence of anus.

Rectum

1. Rectum opening into some other viscus.

2. Normal rectum and anus but some other viscus opening into the rectum.

3. Rectum arrested in its descent.

4. Rectum absent (including entire colon sometimes).

In treating the subject of malformation, two divisions will be made for convenience of description: those presenting the symptoms of partial obstruction, and those which cause complete intestinal obstruction.

Partial Obstruction

In this classification, the malformations vary from the mild degree of partial occlusion to that of the rectum opening into some other organ allowing more or less fecal matter to escape from the bowel. They present conditions, in most instances, not immediately dangerous to the life of the child. The malformations may be:

1. Partial occlusion.

2. Abnormal narrowing.

3. Anal opening at some other abnormal point.

4. Rectum opening into some other viscus.

5. Normal rectum and anus but some other viscus opening into the rectum.

Partial Membranous Occlusion of the Anus. The occlusion occurs at different levels of the anal canal, and consists of a membrane or fold of tissue. If the membrane is located at the margin of the anus, it may be composed of skin. When extending from the sacrum to the coccyx, it may represent the central rape in the form of a narrow, cord-like extension with an opening on each side over the anal canal, allowing the escape of zirconium. When the occlusion is higher up, the membrane will be composed of much-butane-ouch tissue, of crescent or circular shape, partially obstructing the anal canal. The histological origin of this occlusion is not known, but seems to be due to an imperfect absorption of embryo logic tissue. When the occlusion is higher up, it is probably due to a fault in the absorption of the anew-rectal partition during fetal life.

This condition is sometimes seen in adult life, when the occlusion happens to be of mild degree and is unnoticed.

Treatment. In cases of Partial Occlusion by a membranous band immediate removal of the obstruction with a knife or scissors should be done; subsequent dilatation may be necessary with the finger.

Abnormal Narrowing of the Anus. This condition may take place at any point in the anal canal, from the external margin to its junction with the rectum, and may extend throughout the whole length of the canal. These cases, to the casual observer, usually present the appearance of a normal anus, and are commonly overlooked until adult life, when the anal canal is found to be narrowed at some portion. The narrowing may be caused by bands of tissue or membrane extending across the sides of the canal, or it may extend the full length of the canal, causing a shortening in its length or breadth.

The size of the normal anal canal at birth is dependent upon the size of the child. For the purpose of diagnosis, the anal canal of the average child at birth should be large enough to admit with ease the index finger of a woman or the little finger of a man's hand. When the sphincters are properly developed, they will gently grasp the introduced ringer, but when the narrowing is abnormal, this sphincter action will not be observed, and it will be found difficult or impossible to introduce the finger further into the canal. Children suffering from this condition are generally supposed to be constipated, as the narrowing of the anal canal interferes with the proper escape of fecal matter. As the child gets older and the fecal matter becomes less fluid, the narrowing causes obstruction and irritation, forcing the patient to strain and suffer considerable pain whenever the bowels are moved. A marked constipation, due to the fear of pain at stool, soon appears, with all its evil effects.

Treatment. An abnormal narrowing of the anus should be dilated with the soft rubber bogie every day, until the aperture is large enough to admit the small finger of the operator.