Portal Venous System

Of the three major venous systems traversing the upper fetal abdomen (i.e., the cardinal, vitelline, and umbilical systems), the latter two are integral to the development of the hepatic vasculature. The right vitelline and left umbilical veins persist, whereas their respective contralateral counterparts are short-lived. The right vitelline vein forms a plexus surrounding the duodenum and extending to the septum transversum, where it interacts with the developing liver cords to form the hepatic sinusoids (Fig. 2-36). The hepatic sinusoids become the

Fig. 2—30. Duplication of the gallbladder in a 66-year-old man, proved at surgery.

(a) Sagittal (left) and transverse (right) ultrasound images show the gallbladders lying side by side. One has cholesterol crystals and sludge in the lumen with a thickened wall (thick arrows). The other gallbladder appears to be normal (curved arrows).

(b) Oral cholecystogram (OCG) opacifies both gallbladders.

(c) Reformatted CT in coronal plane after OCG shows both gallbladders.

(Reproduced from Ozgen et al.54)

intrahepatic portal vein branches and the hepatic veins. Meanwhile, a single oblique channel among the hepatic sinusoids becomes dominant (the ductus venosus) and drains directly into the inferior vena cava (IVC). The right umbilical vein disappears during the second month, whereas the left umbilical vein persists and anastomoses with the ductus venosus.

The ductus venosus (Fig. 2-37) develops to provide a direct communication between the placental and systemic venous circulations, with a variable proportion of

Cholelithiasis

Fig. 2—31. Duplicated gallbladder with cholelithiasis after cholecystectomy in a 45-year-old man.

CT after OCG shows the ectopically located gallbladder with a stone in it (arrow}. A widened common bile duct is present (arrowhead). The patient had a repeat cholecystectomy.

(Reproduced from Ozgen et al.54)

Fig. 2—31. Duplicated gallbladder with cholelithiasis after cholecystectomy in a 45-year-old man.

CT after OCG shows the ectopically located gallbladder with a stone in it (arrow}. A widened common bile duct is present (arrowhead). The patient had a repeat cholecystectomy.

(Reproduced from Ozgen et al.54)

umbilical venous blood continuing to traverse the sinusoids via the left portal vein. The ductus venosus is obliterated soon after birth, and its remnant is called the ligamentum venosus. The umbilical vein also atrophies and is henceforth known as the ligamentum teres. A narrow umbilical vein lumen often remains patent into adulthood (Fig. 2-38). The plexus investing the duodenum coalesces to form the superior mesenteric and portal veins. The cephalic portion of the vitelline vein gives rise to the hepatic veins and upper inferior vena

34 37

cava.

Persistence of the primitive hepatic sinusoids, sub-hepatic ventral intervitelline anastomotic vein, ductus venosus, and anastomosis between the right subcardinal vein and right vitelline vein lead to intrahepatic portal-systemic venous shunts, preduodenal portal vein, patent ductus venosus, and fistula between the portal vein and IVC, respectively.65,66 Associated anomalies of foregut, midgut, and hindgut as well as those of the vascular system may accompany these malformations. Incomplete obliteration of the anastomoses leads to a formation of a diverticula-like protrusion of the vein, namely "aneurysm" of the portal vein or of any vein. Excessive obliteration of these anastomoses may produce agenesis or hypogenesis of the portal vein and branches.

Fig. 2-32. Choledochal cyst.

Intraoperative cholangiogram demonstrates fusiform dilatation of the common bile duct, a form of choledochal cyst. Note the high junction of the pancreatic duct and the distal common bile duct (open arrow), commonly cited as a cause of choledochal cyst formation. (From Javors BR.3)

Fig. 2-32. Choledochal cyst.

Intraoperative cholangiogram demonstrates fusiform dilatation of the common bile duct, a form of choledochal cyst. Note the high junction of the pancreatic duct and the distal common bile duct (open arrow), commonly cited as a cause of choledochal cyst formation. (From Javors BR.3)

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Post a comment