THE LIVER. 587 



In another class of cases, in addition to the local and mechanical 

 effects of a thrombus, the latter may be infectious, then there are ne- 

 crotic changes and suppurative inflammation in the walls of the ves- 

 sels or in the liver tissue about them. The thrombi are apt to soften and 

 break down, and the fragments may be disseminated through the smaller 

 trunks of the portal vein. In this way, by the distribution through the 

 smaller vessels of a disintegrated thrombus from a large trunk, or by the 

 introduction into the branches of the portal vein of purulent or septic 

 material from some of the abdominal viscera or from wounds, multiple 

 foci of purulent inflammation in the portal vein, and multiple abscesses 

 involving the liver tissue, may be produced. In many cases the pres- 

 ence of bacteria may be detected in the inflammatory foci. 



These soft thrombi of the portal vein and the accompanying pyle- 

 phlebitis and abscess are induced in a variety of ways. Ulceration of 

 the intestines and stomach, abscesses of the spleen, suppurative inflam- 

 mation of the mesentery and mesenteric glands, inflammation and ulcer- 

 ation of the bile ducts from, gall stones, inflammation of the umbilical 

 vein in infants, may all induce thrombi in their respective veins, which 

 may be propagated to the portal vein or may give rise to purulent or 

 septic eniboli. Two cases are recorded in which a fish bone in the por- 

 tal vein induced suppurative inflammation in that vessel. 



Infarction of the liver after embolism is rare owing to the anastomosis 

 between the branches of the hepatic artery and the capillaries of the lob- 

 ules. Occasionally atrophy of the parenchyma in circumscribed areas 

 follows thrombosis or embolism of branches of the portal vein. 



In infants inflammation of the umbilical vein may not only induce 

 inflammation of the portal vein and abscesses in the liver, but multiple 

 abscesses in various parts of the body, and acute peritonitis may follow. 



Rupture of the Portal Vein, with fatty degeneration of its walls, has 

 occurred in a few instances. 



Chronic Endophlebitis, with atheroma and calcification, may occur in 

 the walls of the portal vein, giving rise to thrombosis. 



Dilatation of the Portal Vein, either uniform or varicose, may occur in 

 various parts of the vessel or its branches. It may be caused by destruc- 

 tion of the liver capillaries in cirrhosis, or by occlusion of the vein by 

 thrombi, tumors, etc. 



THE HEPATIC VEINS. 



The hepatic veins present lesions similar to those of the portal vein and 

 its branches, but they are much less frequent. The veins may be dilated 

 by obstruction to the passage of venous blood into the heart. They may 

 be the seat of acute and chronic inflammation, and soft thrombi and sup- 

 purative inflammation may be produced by abscesses in the liver. Earely 

 there is a localized obliterating phlebitis in the hepatic vein followed by 

 chronic congestion, interstitial inflammation, and thrombosis. ' 



1 Consult for obliterating phlebitis of the main trunks of the hepatic vein as a cause 

 of death, Chiari, Ziegler's Beitr., Bd. xxvi., p. 1, 1899, bibliography. 



