<prompt> In patients with cirrhosis of the liver the site of obstruction in the poal system is in the :Hepatic veinPost sinusoidalExtra hepatic poal veinSinusoids  <response>: Answer is D Sinusoids: When cirrhosis is complicated by poal hypeension the increased resistance is usually sinusoidar-Harrisons 15th1759 Poal hypeension 10 mm Hg: Normal poal pressure 5 to 10 mmHg most commonly results from increased resistance to poal blood flow. Increased resistance can occur at three levels: Presinusoidal Anatomically outside the liver eg. Poal vein thrombosis Within the liver but proximal to sinusoids eg. Schistosomiasis Sinusoidal Cirrhosis When cirrhosis is complicated by poal hypeension, the increased resistance is usually sinusoidal Post sinusoidal Outside liver, at level of hepatic veins - Budd chiarri syndrome In the inferior vena cava - Thrombosis In the liver but distal to sinusoid - Venoocclusive disease Remember : Cirrhosis is the most common cause of poal hypeension in the United States.Q Poal vein obstruction is the second most common cause. Q 