Portal hypertension can happen because the liver is damaged and is slowly being replaced with scar tissue. Portal hypertension can also happen after a blood clot forms in the portal vein, acting like a “plug.” This is called portal vein thrombosis. Portal vein thrombosis interferes with normal blood flow from the portal vein to the liver creating an increase in pressure in the portal vein.
Blood backs up behind this plug, causing the body to find alternative ways for the blood to get around the liver and back to the heart. This leads to the formation of “varices” or abnormal blood vessels throughout the stomach, intestine and esophagus. Varices are unable to compensate for the loss of blood flow through the large portal vein.
Consequently, blood flows through the varices under very high pressure and when blood bursts through the thin walled varices, bleeding occurs. If the bleeding is into the esophagus or stomach or anywhere else in the intestinal tract, blood can come out either the mouth or with bowel movements.
What causes pediatric portal hypertension?
Most children with portal hypertension also have liver disease. Scar formation in the liver can interfere with the normal flow of portal blood to the liver and causes blood pressure in the portal vein to increase. Children with portal vein thrombosis do not have liver disease, but develop portal hypertension because the portal vein itself is blocked and unable to bring blood in a normal way to the liver. The liver in these children is otherwise normal.
Portal vein thrombosis is also known as extra-hepatic portal vein thrombosis (EHPVT) because the obstruction or blockage happens before the blood in the vein reaches the liver. The obstruction acts like a dam in preventing blood from reaching the liver easily. The body therefore forms alternate venous channels that the blood can use to get back to the heart. These channels are called “varices.”
Very often, the reason why children develop EHPVT is unknown. Some children may have had an IV in their umbilical vein at birth, but more often than not, the cause for the obstruction is unknown (this is called idiopathic).
Signs and symptoms
Children with EHPVT may have a variety of different symptoms. The average age at which children are first diagnosed with EHPVT is between two and four years, although it can be diagnosed as early as within the first 12months or later as adults. Common symptoms include:
- Distended abdomen
- Enlarged spleen
- Vomiting blood
- Blood tests that show low platelet and white blood cell counts
Diagnosis
Your child’s diagnosis of EHPVT may be suspected by his/her symptoms and confirmed by an ultrasound examination of the liver and veins around the abdomen. A CT or MRI scan of the abdomen can also help make the diagnosis
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