This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
A 7 year old girl from Bihar presented with three episodes of massive hematemesis and melena. There is no history of jaundice. On examination, she had a large spleen, non-palpable liver and mild ascites. Portal vein was not visualized on ultrasonography. Liver function tests were normal and endoscopy revealed esophageal varices. The most likely diagnosis is – 
Select and explain. 
A. Kala azar with portal hypertension, B. Portal hypertension of unknown etiology, C. Chronic liver disease with portal hypertension, D. Portal hypertension due to extrahepatic obstruction
D: Portal hypertension due to extrahepatic obstruction
Answer: D: Portal hypertension due to extrahepatic obstruction 
Explanation: Differentiation between Extrahepatic and Hepatic / Post hepatic portal hypertension 

Post sinusoidal and hepatic causes of portal hypertension will have
evidence of Liver parenchymal damage / deranged LFT (jaundice)
a dilated portal vein on ultrasonography
Extrahepatic presinusoidal obstruction will not have any effect on the Liver and hence there will be no evidence of hepatocellular damage.
No jaundice / No raised deranged LFT

Also non visualization of portal vein is a characteristic of portal vein thrombosis, an Extrahepatic cause.

Esophageal varices and splenomegaly are a manifestation of portal hypertension and will be present in all the above sites of obstruction.