Portal hypertension most commonly occurs when there is an obstruction to normal portal blood flow The lesion may be prehepatic (i.e., portal vein thrombosis or splenic vein obstruction), intrahepatic (i.e., cirrhosis from BA, α1 -antitrypsin deficiency, or cystic fibrosis), or posthepatic (i.e., hepatic vein thrombosis or tumor) Prehepatic disease in children is most commonly due to portal vein thrombosis from omphalitis, but may also be related to sepsis, severe dehydration, or prothrombotic conditions Globally, schistosomiasis is a leading cause of portal hypertension due to intrahepatic parasitic disease causing inflammation, fibrosis, and obstruction (See Table 91.1 for additional causes of portal hypertension in children.) Portal hypertension is typically a clinical diagnosis through recognition of the signs and symptoms of portal hypertension, such as the development of ascites, GI bleeding, identification of varices without active bleeding, or splenomegaly Additional diagnostic testing such as ultrasound, liver biopsy, or measurement of the portal pressure gradient would, of course, supplement any new diagnosis The effects of portal hypertension are systemic, and complications can affect every organ system ( Table 91.2 ) The most common complication, with high morbidity and mortality, is GI hemorrhage from the development of portosystemic varices (i.e., gastric or EV), or congestive or hemorrhagic gastritis (Variceal bleeding is discussed in the Gastrointestinal Bleeding section of this chapter.) Effects on the circulatory system are complex and multifactorial, but ultimately result in an increased cardiac output, hypervolemia, decreased systemic vascular resistance, and hypotension This is largely due to an overall decrease in venous and splanchnic arterial tone, retention of sodium and free water, and subsequent increase in circulatory volume and venous return The increase in venous return and decreased peripheral resistance (mediated by a variety of vasoactive factors such as nitric oxide) result in an overall increase in cardiac output These changes in circulatory physiology contribute to additional complications such as ascites, hepatorenal, and hepatopulmonary syndrome Ascites results from an imbalance in the oncotic and hydrostatic pressures within the abdominal vasculature Hydrostatic pressure is increased secondary to the increased pressure within the draining splanchnic and portal system, as well as the increased circulating blood volume from factors discussed above In addition, there may be a decrease in oncotic pressure as the liver’s synthetic function deteriorates Treatment for ascites may include fluid restriction, diuretic therapy, and albumin administration; however, one must be cognizant