Portal vein : is a vessel which carries nutrients and metabolites like nitrogen from digestive system- stomach and  intestine- to liver

Systemic circulation: is a vascular system which supports blood circulation for whole body.in this system posterior and anterior vana cava as main veins carry deoxygenated blood to the heart  but  Aorta as a main artry carries the blood from the heart for other artries which  support  organs of body.

Portosystemic shunt: is a connection between Portal vein and vena cava.

Pathogenesis: in intestine  metabolism  produces toxins and  nitrogens.These metabolites are absorbed from the intestine and enter the portal vein.Portal vein carries the toxins and nitrogen to liver to detoxify and  convert  to urea respectively.In Porto-systemic shunt instead of liver These waste materials are carried to the vena cava.Therefore blood toxins and nitrogen is going up.They  affect brain and causes nervous system symptoms which is named as hepatic encephalopathy.

On the other hand because of deprivation of liver from normal blood circulation, necrosis of liver cells is continued which leads to increase the liver enzymes.Also bilirubin is increased and liver starts to become shrinkage.Porto-systemic shunt can be a congenital or acquired,one shunt or several shunts, outside or inside the liver.

Symptoms: constipation and diarrhea periodically and even vomiting, blindness and convulsion, red urine and even urinary stone,furious eating and affinity to eat unusual things like  fecal material, slow recovery after sedation or anesthesia.One or some these symptoms can be seen in patients.

Diagnosis : On the basis of biochemical, radiography , ultrasound and scintigraphy portosystemic shunt  can be diagnosed.

Treatment: If it is one shunt and it is located outside of liver prognosis is good with surgery.Most often in congenital defect form  this kind of shunt is seen.