Icterus Or Jaundice is a condition in which the blood contains a yellow pigment which stains the tissues of the body generally. The pigment is usually that of bile, namely, bilirubin. This substance is elaborated by the hepatic cells and secreted as a constituent of the bile. When the exit of the bile is hindered by obstruction of the ducts the pigment is re-absorbed and passes into the blood. Icterus which is thus due to the bile pigment is called Hepatogenous, that is, derived from the liver.

We have already seen that hsematoidin is of similar constitution to bilirubin, and we may presumably have icterus from the formation of this pigment in the blood by destruction of the red corpuscles independently of the bile. This form of icterus is called Hematogenous. The exact domain of this form is not determined. The icterus of some acute diseases such as pyaemia and typhus fever is hsematogenous. More doubtful is the Icterus neonatorum. This form of jaundice occurs in a large number of new-born children, and is usually regarded as due to a destruction of red corpuscles, occurring in consequence of the changes in the circulation at birth.

Cells containing blood corpuscles from the neighbourhood of a haemorrhage.

Fig. 49. - Cells containing blood-corpuscles from the neighbourhood of a haemorrhage; a, with fresh corpuscles; b, with dark granules from disintegration of red corpuscles.

It is asserted by Birch-Hirschfeld that this icterus is hepatogenous. He says that the sudden change in the circulation at birth causes cedema of the interstitial connective tissue of the liver, and that this produces obstruction of the ducts. Cohnheim agrees with Birch-Hirschfeld that the icterus is probably hepatogenous, but does not see sufficient evidence of oedema. He suggests that as there is at birth a sudden increase in the secretion of bile, the ducts may take some time to accommodate themselves. Becklinghausen believes the icterus to be haema-togenous on the apparently sufficient ground that the fasces are coloured with bile, and that therefore the bile ducts are not obstructed.

A peculiar feature in icterus neonatorum is the occurrence of Crystals of haema-toidin or bilirubin in the kidneys, and also in the tissues and blood. That is to say, the pigment not only stains the tissues, but is deposited in the crystalline form. It is probable, however, that this crystallization is a post-mortem phenomenon. Hasmatoidin crystals may be found even where there is not enough pigment present to produce jaundice.