It appears then that by the salutary provi sions of nature the front of the abdominal pa rietes is well supported, and the contained viscera protected from protrusion ; and even if the operations by which the umbilicus is closed should be accidentally suspended or interfered with, (as by the presence of a hernia for in stance,) the disposition is not lost, and the aper ture preserves its tendency to close and become obliterated for the first five or six years of childhood. Thus at any time within that period there may be a reasonable probability of obtain ing a permanent cure of umbilical hernia; whereas after the age of ten or twelve years this disposition ceases to operate, or at least is greatly impaired, and there is little or no chance of so fortunate an occurrence.
The condition in which the umbilicus exists at and after birth divides the hernia that occur in this situation into different orders according as they may appear at the period of birth or afterwards. Scarpa considers the disease to consist of only two species, the congenital and the adventitious—the congenital being that which appears in the infant when born, and the other occurring at any subsequent period. Lawrence speaks of three kinds, the congenital, that which appears at birth, and in which the protruded viscera are lodged in the umbilical cord; the umbilical hernia of children occur ring after the navel has been formed, but pro trading through the original deficiency in the lima alba; and the hernia of adults, which has some peculiarities that shall be noticed here after.
The congenital umbilical hernia seems to depend rather on a deficiency of the anterior walls of the abdomen than on any other cause, and in the cases in which it is observed, the aperture at the navel is much larger than it should naturally be, and its tendinous edges excessively thin and weak. The deficiency of the abdominal parietes ranks amongst natural malformations, and it is astonishing to what an extent it has been observed. The entire of the tendinous front of the belly has been found imperfect, and nearly the whole of the viscera displaced, thus forming an immense rupture covered at its base and for some extent farther by the skin and superficial investments of the body, and in its remaining part by the transpa rent spongy substance of the umbilical cord. The contents of these ruptures are greatly varied : the liver or a portion of it, the spleen, the stomach, the greater and the lesser intestines have all been occasionally found thus circum stanced, but more particularly the omentum, which, as might be anticipated from its situation, is observed to constitute a part of almost every umbilical hernia both in the old subject and in the young. Whenever there is such a defi ciency in the abdominal parietes, the pressure an infant undergoes in coming into the world materially contributes to the production of hernia, and accordingly it is observed most fre quently after a protracted and difficult labour; and if it is large, and the contents of the ab domen extensively deranged or displaced, it is in general fatal, the infant seldom surviving beyond two or three days, and perhaps not so long. In this affection there seems to be a
want of correspondence between the size of the viscera and that of the abdominal cavity, the former appearing enlarged and swollen ; and there is seldom a possibility of returning the rupture, or of maintaining it so if reduced. There is in general also in these cases some other malformation or incomplete development to account for the fatality that so uniformly attends them. But if, on the other hand, the hernia is small, the case is by no means neces sarily attended with danger: the rupture may be reduced, but it has a tendency to return when ever the child cries or makes any other exertion, and it is extremely difficult to restrain it by a bandage ; but if it can be kept up for a few months, the umbilical aperture closes as it would have done if there had been no pro trusion, and the cure is permanent and com plete.
If, before the navel has become cicatrized and closed, a portion of any viscus should happen to be protruded through it, and its progress towards obliteration thus interrupted ; or if the contraction has been delayed longer than usual, and an aperture thus left ready to favour the escape of a part of intestine from its natural situation, the rupture will be of the second form mentioned, namely, the umbilical hernia of the child. This differs from that of the infant inasmuch as it is covered by the skin and the cicatrized knot of the navel, and does not lie within the cord ; and from that of the adult, so far as, if replaced and prevented from again protruding, the aperture will gradually contract, and thus a permanent cure be obtained, which is scarcely to be expected at a more advanced period of life. It has been already mentioned that Scarpa considered the perfect contraction of the umbilicus to be completed in about two months, and at the end of that time that it is even firmer than other parts : he moreover seemed to think this part materially strength ened by the remains of those vessels which before birth made up a part of the cord. The umbilical vein passing from the navel upwards towards the liver, and the hypogastrie arteries passing downwards, are at the umbilicus united by a cicatrix to the skin and to each other, and conti Unite to prevent the yielding of the part as soon as they become ligamentous. The point of union of these vessels must be pushed forwards as well as the integuments in adven titious hernia, and hence it happens that when the umbilical aperture is only of its natural size, the rupture that takes place (if any) is small; and in cases where it is large and the abdominal parietes deficient in this point, the tumour is flatter and more compressed than might have been otherwise expected, and sonic of these vessels are found lying on it and forming a part of its covering.