Occurrence.—Icterus neonatorum occurs, with few exceptions, in all children, with varying intensity. Reports vary widely concerning its frequency; thus Seux declares that 15 per cent., and Bouchut 331 per cent. of all newborn children have icterus, whereas, according to Poruk 79.9 per cent., according to Cruse S4.4 per cent. and according to Breschet all newborn children become icteric. My own observations arc most nearly in accord with those of Cruse. The icterus is especially pronounced in premature children, just as, in general, the body weight and the intensity of the icterus are inversely proportional (Cruse). The icterus is said to be especially intense in the children that show shortly after birth a pronounced congestion of the skin. Children in whom the umbilical cord is tied early are said to have icterus less often than those in whom the cord is not tied till the cessation of its pulsations. The children of primiparte are said to become more intensely icteric than children of multiparty (Kehrer).
Pathological examinations in eases of icterus neonatorum are to some extent rendered less conclusive, because it is always some complication which has lead to the fatal termination. Among the findings which must be ascribed to icterus neonatorum, the observation that the liver is often not especially yellow or else only in spots, deserves first mention. This, however, applies also to other forms of icterus. The finding of bilirubin crystals in the kidneys (Merkel, Virchow's haluatoidin-infaret) is peculiar; these are found in the form of bunches of needles or rhombic platelets, in the tips of the papillae. Orth found these crystals in every case of icterus neonatorum and more over not only in the kidneys but also in the blood, in the adipose tissues, the brain and other organs. In examining the cadavers of still-born infants, or those of children dying shortly after birth, Neumann found bilirubin crystals in the fat cells of the peritoneum and in the afferent blood vessels. The precipitation of bilirubin in the fatty tissue may be due to the withdrawal, by the fatty acids in the fat cells, of the alkali, which is the solvent for bilirubin.
For the rest, one finds, at autopsy, a yellow discoloration of most of the internal organs; this is especially marked in the serous membranes, the intima of the vessels, in exudates and transudates and is not notice able in the spleen or kidneys.
causes of icterus neonatorum have not yet been clearly established. It can be said that the views concerning the pathogenesis of icterus neonatorum are, in general, parallel to the theories of icterus in the adult and to those of experimental icterus. If we aceept the dictum of Stadelmann "without a liver no icterus," then all theories which seek to explain icterus without volvement of the liver must be discarded. We know from the celebrated experiments of Naunyn and Alinkowski that the liver is not only the organ for the excretion of the bile but also for its elaboration. In the liver arise the characteristic components of the bile, the bile-pigment as well as the biliary acids. It is true that occasionally bilirubin arises, without involvement of the liver, from the blood-pigment, (e.g., in Zia tn
orrhages into the tissues) but icterus has never been observed in this connection. The forms of icterus in which biliary acids are demonstrated in the urine must unqualifiedly be attributed to the resorption of bile in the liver. This presence of the biliary acids has been demonstrated for icterus neonatorum and moreover not only in the urine (Halberstam) but also, earlier, in the pericardial fluid (Birch-Hirschfeld and Hof meister).
Therefore, all theories which have sought to explain icterus, by means of a hyperfemia of the skin, capillary hremorrhage and the like, have only a historical interest. Just as little do those theories deserve consideration, which would attribute the icterus to luemolysis and trans formation of blood-pigment to bile-pigment within the circulatory apparatus (hf.ematogenous jaundice, Neumann, Violet, and others). The finding of biliary acid in the urine absolutely excludes such a theory. However, one theory, that of Luincke, which explains icterus without liver, is not demolished by this fact; according to Luincke, the biliary components are resorbed from the meconium; since, however, the bil iary acids and pigments are normally excreted in the liver during their passage through the portal circulation and therefore do not enter the general circulation, Luincke assumes that a portion of the blood in the mesenteric veins, laden with the biliary constituents of the meconium, passing through the as yet unclosed ductus Arantii, enters the vena cava ascenders and thus into the general circulation without passing through the liver. Against this theory it must be noted that, according to Meekel, the ductus Arantii in the newborn is usually hardly passable by a sound, further that meconium is acid in reaction, whereas bilirubin is soluble in alkaline fluids and finally that the expulsion of the meconium during parturition, for example with asphyxia, does not hinder the occurrence of icterus. 'We must, therefore, look to the liver as the place of origin for icterus. The most satisfactory theory would be one that would connect icterus neonatorum with a demonstrable stasis of bile. To this end, Peter Franck assumed a closure of the ductus choledochus by means of the meconium; Virchow, by means of a plug of mucus; and Cruse, through cast off epithelium; but these assumptions do not accord with the facts; no more is the theory of Birch-Hirschfeld right, according to which an oedema of the capsule of Glisson is the cause of the stasis; the oedema which Birch-Hirschfeld found was not verified by other investigators and must be attributed to complications (pneu monia, etc.). By anatomical examinations of the liver, Boucliut's hypothesis of a hepatitis and Epstein's theory of a catarrh of the finer gall-ducts have been demolished. The assumption of Ritter and Ep stein that icterus of the newborn is, in the majority of instances, of a septic nature, seems, in the light of clinical observation, untenable; the well-being of icteric children and the absence of any other symptoms of sepsis speak against any such assumption.