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Portal hypertension in children


Normal pressure in the portal venous system ranges from 5 to 10 mm Hg. Portal hypertension is defined as portal venous pressure exceeding 10 mm Hg. Hepatic venous pressure gradient (HVPG) is a surrogate marker of portal hypertension. Normal HVPG is between 1 and 4 mm Hg. Portal hypertension develops when HVPG is more than 5 mm Hg. HVPG greater than 10 mm Hg is the prediction of the development of varices in adults. Data are limited in children but suggest that there may be similar pressure thresholds for the development of complications in the pediatric population.

Pathophysiology of portal hypertension (see Chapters 5 and 74 )

The portal system is a low-pressure venous system that carries partially oxygenated blood to the liver, whereas the liver receives highly oxygenated blood through hepatic arteries. Both systems combine within the sinusoidal spaces. Portal hypertension occurs when there is either increased portal resistance or increased portal blood flow. Varices are abnormal venous communications between the portal and systemic circulation that develop to decrease the pressure in the portal venous system.

Etiology (see Chapter 74 )

In broad terms, portal hypertension is divided into two categories, cirrhotic secondary to chronic liver disease and noncirrhotic, for example, due to portal venous occlusion, congenital hepatic fibrosis (CHF), nodular regenerative hyperplasia (NRH), nonalcoholic fatty liver disease (NAFLD), sinusoidal obstruction syndrome (SOS), rare metabolic diseases (Gaucher and Zellweger syndromes), schistosomiasis, and hepatoportal sclerosis. On the other hand, pediatric portal hypertension can be categorized into three main types, prehepatic, hepatic, and posthepatic, as described in Box 76.1 . Overall, the most common cause of portal hypertension in children is as a result of intrahepatic, sinusoidal causes from a variety of liver diseases predominantly from biliary atresia. Extrahepatic portal vein obstruction (EHPVO) is the most common cause of noncirrhotic portal hypertension in children. Causes of EHPVO are summarized in Box 76.2 .

BOX 76.1
Causes of Portal Hypertension in Children

Prehepatic

  • Portal vein thrombosis

  • Superior mesenteric vein thrombosis

  • Splenic vein thrombosis

  • Congenital stenosis of the portal vein

Hepatic

  • Presinusoidal

  • Idiopathic portal hypertension

  • Primary sclerosing cholangitis

  • Primary biliary cirrhosis

  • Sinusoidal

  • Biliary atresia

  • Autoimmune hepatitis

  • Wilson disease

  • Hepatitis B and C

  • α 1 Antitrypsin deficiency

  • Glycogen storage disease type IV

  • Toxins (vitamin A toxicity)

  • Cystic fibrosis

  • Congenital hepatic fibrosis

  • Caroli disease

  • Choledochal cyst

  • Familial cholestasis

  • Gaucher disease

  • Steatohepatitis

  • Peliosis hepatis

  • Schistosomiasis

Post sinusoidal/post hepatic

  • Budd-Chiari syndrome

  • Hepatic vein occlusion

  • Congestive right-sided heart failure

  • Inferior vena cava obstruction

BOX 76.2
Causes of Extrahepatic Portal Vein Obstruction

  • Idiopathic

  • Prothrombotic state

    • Portal vein injury

    • Umbilical vein catheterization

    • Abdominal surgery

    • Trauma

    • Liver transplantation

  • Local inflammatory conditions

    • Intraabdominal abscess

    • Abdominal sepsis

    • Inflammatory bowel disease

    • Pancreatitis

    • Omphalitis

    • Severe dehydration

Clinical presentation (see Chapter 79 )

Gastrointestinal bleeding

Gastrointestinal hemorrhage from variceal bleeding is the most frequent presentation (in about two-thirds of cases) of portal hypertension in children (see Chapter 80, Chapter 81, Chapter 82, Chapter 83 ). Varices are abnormal venous communications between the portal and systemic circulation that develop to decrease the pressure in the portal venous system (see Chapter 5 ). [8]When the portal vein is congested, collateral blood vessels develop at the junction of the high-pressure portal vein and low-pressure systemic vein forming varices, mainly in the esophagus and stomach but also around the umbilicus and rectum. Gastroesophageal varices are more prone to bleeding because of their location and exposure to acid and food. In children with short bowel syndrome, stomal varices are a site for low resistance and a common source of hemorrhage. Gastrointestinal bleeding can present with hematemesis or melena. Gastrointestinal bleeding from ruptured varices often follows upper respiratory tract infection, fever, or nonsteroidal antiinflammatory drug (NSAID) ingestion. It can also occur in the setting of prolonged gastroesophageal reflux as a result of erosions over the varices. In adults HVPG of 12 mm Hg appears to predict the risk of bleeding from esophageal varices. There is limited data; however, mortality associated with first variceal bleed in children has been reported close to 1%. This may be because biliary atresia and extrahepatic portal vein thrombosis are two common causes of portal hypertension in children, and portal hypertension develops during the early course of these disease processes when the liver is very well compensated.

The classification of esophageal varices is based on endoscopic findings. There are some interobserver variations regarding the grading of esophageal varices. The most accepted classification is as follows :

Grade 0 No esophageal varices
Grade 1 Small and nontortuous esophageal varices
Grade 2 Tortuous varices but limited to less than one-third of the distal esophageal radius
Grade 3 Large and tortuous esophageal varices occupying greater than one-third of the distal esophagus radius

According to the Japanese Research Society for Portal Hypertension, grading of esophageal varices can also be described as follows :

  • Grade 1: Flattened by insufflation.

  • Grade 2 and 3: Not flattened by insufflation. Confluency differentiates grade 2 from 3, with grade 3 confluent around the circumference of the esophagus.

Splenomegaly

Splenomegaly is the second most common finding in children with portal hypertension. Hypersplenism manifests as left upper quadrant discomfort or pain; incidental finding on physical exam; and less commonly by thrombocytopenia, leukopenia, petechia, or ecchymosis. Splenic size does not appear to correlate with portal hypertension. , It rarely requires surgical intervention in cases of symptomatic anemia or severe physical discomfort.

Ascites

Ascites is one of the major complications of portal hypertension. It likely develops because of sodium and fluid retention as a result of increased portal pressure. Ascites might be a presenting sign in 7% to 21% of children with portal hypertension. Paracentesis in children is safe but only reserved for cases when ascites is refractory for treatment and causing respiratory compromise or concern for peritonitis to perform cell count and culture. Treatment includes salt restriction and diuretic therapy. The diuretic of choice is spironolactone, but combination treatment with furosemide might be necessary for patients who do not respond to spironolactone alone. Albumin infusion may be needed to increase intravascular osmotic pressure followed by diuretic dosing.

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